#LyX 1.3 created this file. For more info see http://www.lyx.org/ \lyxformat 221 \textclass article \language english \inputencoding default \fontscheme default \graphics default \float_placement !htbp \paperfontsize 10 \spacing single \papersize letterpaper \paperpackage a4 \use_geometry 1 \use_amsmath 0 \use_natbib 0 \use_numerical_citations 0 \paperorientation portrait \leftmargin 1in \topmargin 0.5in \rightmargin 1in \bottommargin 0.65in \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \defskip medskip \quotes_language english \quotes_times 2 \papercolumns 1 \papersides 1 \paperpagestyle default \layout Title \added_space_top vfill \added_space_bottom vfill Installing and Running mod_log_sql \layout Author Christopher Powell, \layout Standard \pagebreak_bottom \begin_inset LatexCommand \tableofcontents{} \end_inset \layout Section Introduction \layout Subsection Homepage \layout LyX-Code http://www.grubbybaby.com/mod_log_sql/ \layout Subsection Summary \layout Standard This Apache module will permit you to log to a SQL database; it can log each access request as well as data associated with each request: cookies, notes, and inbound/outbound headers. Unlike logging to a flat text file -- which is standard in Apache -- a SQL-based log exhibits tremendous flexibility and power of data extraction. (See section \begin_inset LatexCommand \ref{sub:why} \end_inset in the FAQ for further discussion and examples of the advantages to SQL.) \layout Standard This module can either replace or happily coexist with mod_log_config, Apache's text file logging facility. In addition to being more configurable than the standard module, mod_log_sql is much more flexible. \layout Subsection Approach \layout Standard This project was formerly known as \begin_inset Quotes eld \end_inset mod_log_mysql. \begin_inset Quotes erd \end_inset It was renamed \begin_inset Quotes eld \end_inset mod_log_sql \begin_inset Quotes erd \end_inset in order to reflect the project goal of database-inspecificity. The module currently supports MySQL, but support for other database backends is underway. \layout Standard In order to save speed and overhead, links are kept alive in between queries. This module uses one dedicated SQL link per httpd child, opened by each child process when it is born. Among other things, this means that this module supports logging into only one MySQL server, and for now, also, only one SQL database. But that's a small tradeoff compared to the blinding speed of this module. Error reporting is robust throughout the module and will inform the administrat or of database issues in the Apache \noun on ErrorLog \noun default for the server/virtual server. \layout Standard Virtual hosts are supported in the same manner they are in the regular logging modules. The administrator defines some basic 'global' directives in the main server config, then defines more specific 'local' directives inside each VirtualHost stanza. \layout Standard A robust "preserve" capability has now been implemented. This permits the module to preserve any failed INSERT commands to a local file on its machine. In any situation that the database is unavailable -- e.g. the network fails or the database host is rebooted -- mod_log_sql will note this in the error log and begin appending its log entries to the preserve file (which is created with the user & group ID of the running Apache process, e.g. "nobody/nobody" on many Linux installations). When database availablity returns, mod_log_sql seamlessly resumes logging to it. When convenient for the sysadmin, he/she can easily import the preserve file into the database because it is simply a series of SQL insert statements. \layout Subsection What gets logged by default? \layout Standard All the data that would be contained in the "Combined Log Format" is logged by default, plus a little extra. Your best bet is to begin by accepting this default, then later customize the log configuration based on your needs. \layout Standard The documentation of the run-time directives includes a full explanation of what you can log, including examples -- see section \begin_inset LatexCommand \ref{sec:ConfRef} \end_inset . \layout Subsection Miscellaneous Notes \layout Itemize Note which directives go in the 'main server config' and which directives apply to the 'virtual host config'. This is made clear in the directive documentation. \layout Itemize The 'time_stamp' field is stored in an UNSIGNED INTEGER format, in the standard unix \begin_inset Quotes eld \end_inset seconds since the epoch \begin_inset Quotes erd \end_inset format. This is superior to storing the access time as a string due to size requirement s: an UNSIGNED INT requires 4 bytes, whereas an Apache date string (e.g. "18/Nov/2001:13:59:52 -0800") requires 26 bytes: those extra 22 bytes become significant when multiplied by thousands of accesses on a busy server. Besides, an INT type is far more flexible for comparisons, etc. \begin_deeper \layout Standard In MySQL 3.21 and above you can easily convert this to a human readable format using from_unixtime(), e.g.: \layout LyX-Code select remote_host,request_uri,from_unixtime(time_stamp) from access_log; \layout Standard The enclosed perl program \begin_inset Quotes eld \end_inset make_combined_log.pl \begin_inset Quotes srd \end_inset extracts your access log in a format that is completely compatible with the Combined Log Format. You can then feed this to your favorite web log analysis tool. \end_deeper \layout Itemize The table's string values can be CHAR or VARCHAR, at a length of your choice. VARCHAR is superior because it truncates long strings; CHAR types are fixed-len gth and will be padded with spaces, resulting in waste. Just like the time_stamp issue described above, that kind of space waste multiplies over thousands of records. \layout Itemize Be careful not to go overboard setting fields to NOT NULL. If a field is marked NOT NULL then it must contain data in the INSERT statement , or the INSERT will fail. These mysterious failures can be quite frustrating and difficult to debug. \layout Itemize When Apache logs a numeric field, it uses a '-' character to mean \begin_inset Quotes eld \end_inset not applicable, \begin_inset Quotes erd \end_inset e.g. the number of bytes returned on a 304 (unchanged) request. Since '-' is an illegal character in an SQL numeric field, such fields are assigned the value 0 instead of '-' which, of course, makes perfect sense anyway. \layout Subsection Author / Maintainer \layout Standard The actual logging code was taken from the already existing flat file text modules, so all that credit goes to the Apache Server group. \layout Standard The MySQL routines and directives were added by Zeev Suraski . \layout Standard All changes from 1.06+ and the new documentation were added by Chris Powell . It seems that the module had fallen into the "unmaintained" category -- it hadn't been updated since 1998 -- so Chris adopted it as the new maintainer. \layout Section Installation \layout Subsection Requirements \layout Itemize A compatible system. mod_log_sql was authored and tested on systems based on Red Hat Linux (Red Hat, Mandrake), but the module should easily adapt to any modern distribution. mod_log_sql has also been ported successfully to Solaris and FreeBSD. \layout Itemize Apache 1.2 or 1.3. Ideally you should already have successfully compiled Apache and understand the process, but this document tries to make it simple for beginners. \layout Itemize The MySQL development headers. This package is called different things on different distros. For example, Red Hat 6.x calls this RPM \begin_inset Quotes eld \end_inset MySQL-devel \begin_inset Quotes erd \end_inset whereas Mandrake calls it \begin_inset Quotes eld \end_inset libmysql10-devel. \begin_inset Quotes erd \end_inset \layout Itemize MySQL >= 3.23.15 configured, installed and running on either localhost or an accessible networked machine. You should already have a basic understanding of MySQL and how it functions. \layout Itemize Optionally, if you want to be able to log SSL information such as keysize or cipher, you need OpenSSL and mod_ssl installed. \layout Subsection Platform-specific notes \layout Standard These installation documents assume a relatively modern GNU/Linux scenario. mod_log_sql has been ported to other platforms; following are notes on compiling the module for those platforms. \layout Subsubsection \begin_inset LatexCommand \label{sub:Solaris} \end_inset Solaris \layout Standard The nanosleep() function used in mod_log_sql relies on linking aginst the librt library. Make the following alterations before proceeding: \layout Enumerate In Makefile, search for the string \begin_inset Quotes eld \end_inset -lmysqlclient -lz \begin_inset Quotes erd \end_inset and change it to read \begin_inset Quotes eld \end_inset -lmysqlclient -lz -lrt \begin_inset Quotes erd \end_inset \layout Enumerate In part \begin_inset LatexCommand \ref{step:Linking} \end_inset of section \begin_inset LatexCommand \ref{sec:Static} \end_inset below, change \begin_inset Quotes eld \end_inset -lmysqlclient -lm -lz \begin_inset Quotes erd \end_inset to read \begin_inset Quotes eld \end_inset -lmysqlclient -lm -lz -lrt \begin_inset Quotes erd \end_inset \layout Subsubsection BSD \layout Standard No notes are available at present, but they are desired. If you have successfully ported mod_log_sql to BSD, \emph on please \emph default contact \begin_inset LatexCommand \url[the maintaniner, Chris Powell]{(chris@grubbybaby.com)} \end_inset and help fill in this section. \layout Subsubsection Win32 \layout Standard No notes are available at present, but they are desired. If you have successfully ported mod_log_sql to Win32, \emph on please \emph default contact \begin_inset LatexCommand \url[the maintaniner, Chris Powell]{(chris@grubbybaby.com)} \end_inset and help fill in this section. \layout Subsubsection OS X \layout Standard mod_log_sql should compile and work out-of-the-box on this platform. Here are some notes from a user successfully running the module on OS X: \layout Quote \emph on The only changes I had to make were to where I had the various libraries installed. \layout Quote \emph on Here are the changes I made to the head of the Makefile: \layout LyX-Code APACHESOURCE = /usr/local/src/apache_1.3.27 \layout Quote \emph on (Wasn't sure if this was really needed or not, so I downloaded the Apache source just in case) \layout LyX-Code APACHEINSTALLED = /usr/sbin \layout LyX-Code APACHEHEADERS = /usr/include/httpd \layout LyX-Code APXS = $(APACHEINSTALLED)/apxs \layout LyX-Code MYSQLLIBRARIES = /usr/local/mysql/lib \layout LyX-Code MYSQLHEADERS = /usr/local/mysql/include \layout Quote \emph on I'm using a binary installation of MySQL and the default apache installation on OS X Client 10.2.3, the locations of these files may vary depending on how you've installed MySQL and will almost certainly be different if you're using OS X Server. \layout Standard My thanks to Tom Wiebe for being the first (to my knowlege) mod_log_sql user on OS X and for providing these notes. \layout Subsubsection Digital Unix \layout Standard Digital Unix, like Solaris, needs to be linked against librt; see section \begin_inset LatexCommand \ref{sub:Solaris} \end_inset . Here are further notes from a user successfully running the module on Digital Unix: \layout Quote \emph on Instead of trying to get the module to remember where the MySQL libraries were, I instead compiled apache with the information: \layout Quote \emph on LDFLAGS='-rpath /isp/mysql/lib/mysql' ./configure ... \layout Quote \emph on Everything worked as expected after that. (The error I got without this was "/sbin/loader: Fatal Error: cannot map libmysqlclient.so" ) \layout Quote \emph on Digital Unix (v4.0f, at least ) appears to follow the same requirements needed by Solaris, so simply adding librt to the module made it compile without errors. \layout Quote \emph on As for the warnings, here's the text: \layout LyX-Code \emph on mod_log_sql.c: In function `extract_request_duration': \layout LyX-Code \emph on mod_log_sql.c:292: warning: long int format, different type arg (arg 4) \layout LyX-Code \emph on mod_log_sql.c: In function `extract_request_timestamp': \layout LyX-Code \emph on mod_log_sql.c:497: warning: long int format, different type arg (arg 4) \layout Quote \emph on Poking around in the code, it looks like the compiler was complaining that what time() is returning doesn't play nicely with %ld by default. I just typecast them as (long)'s and the warnings went away ( not that the module wasn't working correctly without them ). \layout Quote \emph on The module works very well so far in testing... hasn't dropped a single log entry yet. \layout Standard My thanks to Jim Turner for permitting me to quote him here, and for being the first known user of mod_log_sql on Digital Unix. \layout Subsection Do I want a DSO or a static module? \layout Standard You need to know the answer to this question before you proceed. The answer is pretty straightforward: what have you done in the past? If you like all your Apache modules to be dynamic, then you should keep doing that. If you're more of an old-school type and prefer to compile the modules right into apache, do that. Both methods work equally well. \layout Standard FWIW, the DSO method is more modern and increasing in popularity because apxs takes care of a lot of dirty little details for you. As you'll see below, the static-module method is a little more complex. \layout Subsection Installation as an Apache DSO (Preferred) \layout Enumerate Perform all the following steps as root so that you have install privs, etc. Unpack the archive into a working directory. \begin_deeper \layout LyX-Code # tar zxf mod_log_sql.tar.gz -C /usr/local/src \layout LyX-Code # cd /usr/local/src/mod_log_sql \end_deeper \layout Enumerate Edit Makefile and change the values of the variables in the first section. \begin_deeper \layout Enumerate These paths are \series bold necessary: \begin_deeper \layout Description APACHEINSTALLED: the location where you installed Apache -- usually /usr/local/a pache, 'locate apxs' can help you find it. \layout Description APACHEHEADERS: The location of your Apache header files, find using 'locate httpd.h' \layout Description MYSQLLIBRARIES: The location of your MySQL libraries, find using 'locate libmysqlclient.so' \layout Description MYSQLHEADERS: The location of your MySQL header files, find using 'locate mysql.h' \end_deeper \layout Enumerate \series bold Optional \series default : if you compiled mod_ssl for Apache and want to log SSL data such as 'keysize' and 'cipher type': \begin_deeper \layout Description MODSSLHEADERS: the location of your mod_ssl header files, find using 'locate mod_ssl.h' \layout Description DB1HEADERS: the location of your db1 header files, find using 'locate ndbm.h' \end_deeper \layout Standard You do \series bold not \series default need to compile SSL support into mod_log_sql in order to simply use it with a secure site. You only need to compile SSL support into mod_log_sql \series bold if you want to log SSL-specific data \series default such as the cipher type. \end_deeper \layout Enumerate IMPORTANT: If you are not logging SSL info, comment out MODSSLHDRS by putting a # character in front of it: \begin_deeper \layout LyX-Code #MODSSLHDRS=/usr/include/... \end_deeper \layout Enumerate Instruct apxs to compile the module as a DSO. \begin_deeper \layout LyX-Code # make dso \layout Standard You should see output similar to the following: \layout LyX-Code /usr/local/Apache/bin/apxs -Wc,-O2 -Wc,-Wall -Wc,-DEAPI -c -I/usr/... \layout LyX-Code gcc -DLINUX=22 -DNO_DBM_REWRITEMAP -DMOD_SSL=208111 -DUSE_HS... \layout LyX-Code gcc -shared -o mod_log_sql.so mod_log_sql.o -Wc,-O2 -Wc,-Wall -Wc... \layout Standard You should see no errors and have a new file called "mod_log_sql.so" in your directory. \end_deeper \layout Enumerate Instruct apxs to install the DSO. \begin_deeper \layout LyX-Code # make dsoinstall \layout Standard You should see output similar to the following: \layout LyX-Code /usr/local/Apache/bin/apxs -i mod_log_sql.so \layout LyX-Code cp mod_log_sql.so /usr/local/Apache/libexec/mod_log_sql.so \layout LyX-Code chmod 755 /usr/local/Apache/libexec/mod_log_sql.so \end_deeper \layout Enumerate Load and activate the module in httpd.conf: \begin_deeper \layout Enumerate Insert this line in the same area as other logging modules, e.g. near \begin_inset Quotes eld \end_inset LoadModule config_log_module \begin_inset Quotes erd \end_inset : \begin_deeper \layout LyX-Code LoadModule sql_log_module libexec/mod_log_sql.so \end_deeper \layout Enumerate Insert this line in the same area as other logging modules, e.g. near \begin_inset Quotes eld \end_inset AddModule mod_log_config.c \begin_inset Quotes erd \end_inset : \begin_deeper \layout LyX-Code AddModule mod_log_sql.c \end_deeper \end_deeper \layout Enumerate Module ordering within httpd.conf is important if you are logging SSL information. Please ensure that \begin_deeper \layout LyX-Code LoadModule ssl_module libexec/libssl.so \layout Standard comes before \layout LyX-Code LoadModule sql_log_module libexec/mod_log_sql.so \layout Standard in your httpd.conf file. If they are out of order, simply cut-and-paste the \begin_inset Quotes eld \end_inset ssl_module \begin_inset Quotes erd \end_inset section so that it is at the top. If you do not, you will get this error when you start Apache: \layout LyX-Code /usr/local/apache/libexec/mod_log_mysql.so: undefined symbol: ssl_var_lookup \layout LyX-Code /usr/local/apache/bin/apachectl startssl: httpd could not be started \layout Standard (mod_log_sql has a dependency on mod_ssl for SSL symbols. If the statements are out of order, mod_log_sql cannot recognize those symbols.) \layout Standard Now skip below to section \begin_inset LatexCommand \ref{sec:Configuration} \end_inset , \series bold Configuration \series default . \end_deeper \layout Subsection \begin_inset LatexCommand \label{sec:Static} \end_inset Installation as a static module compiled into httpd \layout Enumerate Perform all the following steps as root so that you have install privs, etc. \layout Enumerate Unpack the archive into a working directory. \begin_deeper \layout LyX-Code # tar zxf mod_log_sql.tar.gz -C /usr/local/src \layout LyX-Code # cd /usr/local/src/mod_log_sql \end_deeper \layout Enumerate \begin_inset LatexCommand \label{step:editMF} \end_inset Edit Makefile and change the values of the variables in the first section. \begin_deeper \layout Enumerate These are \series bold necessary: \begin_deeper \layout Description APACHEINSTALLED: the location where you installed Apache -- usually /usr/local/a pache, 'locate apxs' can help you find it. \layout Description APACHESOURCE: the location of your Apache \series bold sources \series default , find using 'locate ABOUT_APACHE' \layout Description APACHEHEADERS: the location of your Apache header files, find using 'locate httpd.h' \layout Description MYSQLLIBRARIES: the location of your MySQL libraries, find using 'locate libmysqlclient.so' \layout Description MYSQLHEADERS: the location of your MySQL header files, find using 'locate mysql.h' \end_deeper \layout Enumerate \series bold Optional \series default : if you compiled mod_ssl for Apache and want to log SSL data such as 'keysize' and 'cipher type': \begin_deeper \layout Description MODSSLHEADERS: the location of your mod_ssl header files, find using 'locate mod_ssl.h' \layout Description DB1HEADERS: the location of your db1 header files, find using 'locate ndbm.h' \end_deeper \layout Standard You do \series bold not \series default need to compile SSL support into mod_log_sql in order to simply use it with a secure site. You only need to compile SSL support into mod_log_sql \series bold if you want to log SSL-specific data \series default such as the cipher type. \end_deeper \layout Enumerate IMPORTANT: If you are not logging SSL info, comment out MODSSLHDRS by putting a # character in front of it: \begin_deeper \layout LyX-Code #MODSSLHDRS=/usr/include/... \end_deeper \layout Enumerate Compile the module. \begin_deeper \layout LyX-Code # make static \layout Standard You should see output similar to the following: \layout LyX-Code gcc -fpic -O2 -Wall -I/usr/local/Apache/include -I/usr/include/mysql -I/usr/lo... \layout Standard You should see no errors and have a new file called "mod_log_sql.o" in your directory. \end_deeper \layout Enumerate Install the module. \begin_deeper \layout LyX-Code # make statinstall \end_deeper \layout Enumerate Change to your Apache source directory. \begin_deeper \layout LyX-Code # cd /usr/local/src/apache-1.3.22/src \end_deeper \layout Enumerate Re-compile your httpd binary as follows. \begin_deeper \layout Enumerate \begin_inset LatexCommand \label{step:Linking} \end_inset Make these changes to Configuration.apaci: \begin_deeper \layout Itemize Append the following string to the EXTRA_LIBS= line. ("/usr/lib/mysql" is from step \begin_inset LatexCommand \ref{step:editMF} \end_inset , and is where your MySQL libraries live): \layout LyX-Code -L/usr/lib/mysql -lmysqlclient -lm -lz \layout Itemize Find the mod_log_config.o line, and insert this line immediately after it: \layout LyX-Code AddModule modules/sql/mod_log_sql.o \end_deeper \layout Enumerate # cp Configuration.apaci Configuration \layout Enumerate # ./Configure \layout Enumerate # make \layout Enumerate # strip httpd \end_deeper \layout Enumerate Test your new apache binary: \begin_deeper \layout LyX-Code # ./httpd -l \layout Standard You should see something like: \layout LyX-Code Compiled-in modules: \layout LyX-Code http_core.c \layout LyX-Code mod_log_sql.c <-- That's the line you're looking for. \layout LyX-Code mod_env.c \layout LyX-Code mod_log_config.c \layout LyX-Code mod_mime.c \layout LyX-Code mod_negotiation.c \layout LyX-Code etc... \end_deeper \layout Enumerate Install your httpd binary. Copy it over your old httpd binary, wherever it lives. You can and should rename your old httpd first so that you can easily revert to that working version in case of bugs with the new version. \begin_deeper \layout LyX-Code # /etc/rc.d/init.d/httpd stop \layout LyX-Code # mv /usr/local/Apache/bin/httpd ~/httpd-save \layout LyX-Code # cp -f ./httpd /usr/local/Apache/bin/ \end_deeper \layout Section \begin_inset LatexCommand \label{sec:Configuration} \end_inset Configuration \layout Subsection \begin_inset LatexCommand \label{sub:PrepDb} \end_inset Preparing MySQL for logging \layout Standard You have to prepare the database to receive data from mod_log_sql, and set up run-time directives in httpd.conf to control how and what mod_log_sql logs. \layout Standard This section will discuss how to get started with a basic config. Full documentation of all available run-time directives is available in section \begin_inset LatexCommand \ref{sec:ConfRef} \end_inset . \layout Enumerate mod_log_sql can make its own tables on-the-fly, or you can pre-make the tables by hand. The advantage of letting the module make the tables is ease-of-use, but for raw performance you will want to pre-make the tables in order to save some overhead. In this basic setup we'll just let the module create tables for us. \layout Enumerate We still need to have a logging database created and ready, so run the MySQL command line client and create a database: \begin_deeper \layout LyX-Code # mysql -uadmin -pmypassword \layout LyX-Code Enter password: \layout LyX-Code mysql> create database apachelogs; \end_deeper \layout Enumerate \begin_inset LatexCommand \label{part:CrTbl} \end_inset If you want to hand-create the tables, run the enclosed 'create-tables' SQL script as follows ( \begin_inset Quotes eld \end_inset create_tables.sql \begin_inset Quotes erd \end_inset needs to be in your current working directory). \begin_deeper \layout LyX-Code mysql> use apachelogs \layout LyX-Code Database changed \layout LyX-Code mysql> source create_tables.sql \end_deeper \layout Enumerate Create a specific MySQL userid that httpd will use to authenticate and enter data. This userid need not be an actual Unix user. It is a userid internal to MySQL with specific privileges. In the following example command, "apachelogs" is the database, "loguser" is the userid to create, "my.apachemachine.com" is the name of the Apache machine, and "l0gger" is the password to assign. Choose values that are different from these examples. \begin_deeper \layout LyX-Code mysql> grant insert,create on apachelogs.* to loguser@my.apachemachine.com identified by 'l0gger'; \end_deeper \layout Enumerate You may be especially security-paranoid and want "loguser" to \emph on not \emph default have "create" capability within the "apachelogs" database. You can disable that privilege, but the cost is that you will not be able to use the module's on-the-fly table creation feature. If that cost is acceptable, hand-create the tables as described in step \begin_inset LatexCommand \ref{part:CrTbl} \end_inset and use the following GRANT statement instead of the one above: \begin_deeper \layout LyX-Code mysql> grant insert on apachelogs.* to loguser@my.apachemachine.com \layout LyX-Code identified by 'l0gger'; \end_deeper \layout Enumerate \begin_inset LatexCommand \label{step:EnaLog} \end_inset Enable full logging of your MySQL daemon (at least temporarily for debugging purposes) if you don't do this already. Edit /etc/my.cnf and add the following line to your [mysqld] section: \begin_deeper \layout LyX-Code log=/var/log/mysql-messages \layout Standard Then restart MySQL. \layout LyX-Code # /etc/rc.d/init.d/mysql restart \end_deeper \layout Subsection A very basic logging setup in Apache \layout Enumerate Tell the module what database to use and the appropriate authentication information. \begin_deeper \layout Standard So, edit httpd.conf and insert the following lines somewhere after any LoadModule / AddModule statements. \emph on Make sure these statements are \begin_inset Quotes eld \end_inset global, \begin_inset Quotes erd \end_inset i.e. not inside any VirtualHost stanza \emph default . You will also note that you are embedding a password in the file. Therefore you are advised to \begin_inset Quotes eld \end_inset chmod 660 httpd.conf \begin_inset Quotes erd \end_inset to prevent unauthorized regular users from viewing your database user and password. \layout Standard \series bold Example \series default : Use the MySQL database called "apachelogs" running on "dbmachine.foo.com". Use username "loguser" and password "l0gg3r" to authenticate to the database. Permit the module create tables for us. \layout LyX-Code LogSQLLoginInfo dbmachine.foo.com loguser l0gg3r \layout LyX-Code LogSQLDatabase apachelogs \layout LyX-Code LogSQLCreateTables on \layout Standard If your database resides on localhost instead of another host, specify the MySQL server's socket file as follows: \layout LyX-Code LogSQLSocketFile /your/path/to/mysql.sock \layout Standard If your database is listening on a port other than 3306, specify the correct TCP port as follows: \layout LyX-Code LogSQLTCPPort 1234 \end_deeper \layout Enumerate The actual logging is set up on a virtual-host-by-host basis. So, skip down to the virtual host you want to set up. Instruct this virtual host to log entries to the table \begin_inset Quotes eld \end_inset access_log \begin_inset Quotes srd \end_inset by inserting a \noun on LogSQLTransferLogTable \noun default directive. (The \noun on LogSQLTransferLogTable \noun default directive is the minimum required to log -- other directives that you'll learn about later simply tune the module's behavior.) \begin_deeper \layout LyX-Code \layout LyX-Code [snip] \layout LyX-Code LogSQLTransferLogTable access_log \layout LyX-Code [snip] \layout LyX-Code \end_deeper \layout Enumerate Restart apache. \begin_deeper \layout LyX-Code # /etc/rc.d/init.d/httpd stop \layout LyX-Code # /etc/rc.d/init.d/httpd start \end_deeper \layout Subsection Testing the basic setup \layout Enumerate Visit your web site in a browser to trigger some hits, then confirm that the entries are being successfully logged: \begin_deeper \layout LyX-Code # mysql -hdbmachine.foo.com -umysqladmin -p -e "select * from access_log" apachelogs \layout LyX-Code Enter password: \layout Standard Several lines of output should follow, corresponding to your hits on the site. You now have basic functionality. Don't disable your regular Apache logs until you feel comfortable that the database is behaving as you'd like and that things are going well. If you do not see any entries in the access_log, please consult section \begin_inset LatexCommand \ref{faq:NothingLogged} \end_inset of the FAQ on how to debug and fix the situation. \end_deeper \layout Enumerate You can now activate the advanced features of mod_log_sql, which are described in the next section. \layout Subsection How to tune logging with run-time directives \layout Subsubsection Instructing the module what to log \layout Standard The most basic directive for the module is \noun on LogSQLTransferLogFormat \noun default , which tells the module which information to send to the database; logging to the database will not take place without it. Place a \noun on LogSQLTransferLogFormat \noun default directive in the VirtualHost stanza of each virtual host that you want to activate. \layout Standard After \noun on LogSQLTransferLogFormat \noun default you supply a string of characters that tell the module what information to log. In the configuration directive reference (section \begin_inset LatexCommand \ref{sub:Frmat} \end_inset ) there is a table which clearly defines all the possible things to log. Let's say you want to log only the \begin_inset Quotes eld \end_inset request time, \begin_inset Quotes erd \end_inset the \begin_inset Quotes eld \end_inset remote host, \begin_inset Quotes erd \end_inset and the \begin_inset Quotes eld \end_inset request \begin_inset Quotes erd \end_inset ; you'd use: \layout LyX-Code LogSQLTransferLogFormat hUS \layout Standard But a more appropriate string to use is \layout LyX-Code LogSQLTransferLogFormat AbHhmRSsTUuv \layout Standard which logs all the information required to be compatible with the Combined Log Format (CLF). \layout Standard If you don't choose to log everything that is available, that's fine. Fields in the unused columns in your table will simply contain NULL. \layout Standard Some of the \noun on LogSQLTransferLogFormat \noun default characters require a little extra configuration: \layout Itemize If you specify 'c' to indicate that you want to log the cookie value, you must also tell the module which cookie you mean by using \noun on LogSQLWhichCookie \noun default -- after all, there could be many cookies associated with a given request. Fail to specify \noun on LogSQLWhichCookie \noun default , and no cookie information at all will be logged. \layout Itemize If you specify 'M' to indicate that you want to log the machine ID, you must also tell the module this machine's identity using the \noun on LogSQLMachineID \noun default directive. Fail to specify \noun on LogSQLMachineID \noun default , and a simple '-' character will be logged in the machine_id column. \layout Subsubsection \begin_inset LatexCommand \label{sub:Ignore} \end_inset Instructing the module what NOT to log using filtering directives \layout Standard One \begin_inset Quotes eld \end_inset accept \begin_inset Quotes erd \end_inset and two \begin_inset Quotes eld \end_inset ignore \begin_inset Quotes srd \end_inset directives allow you to fine-tune what the module should not log. These are very handy for keeping your database as uncluttered as possible and keeping your statistics free of unneeded numbers. Think of each one as a gatekeeper. \layout Standard \emph on It is important to remember that each of these three directives is purely optional. mod_log_sql's default is to log everything. \layout Standard When a request comes in, the contents of \noun on LogSQLRequestAccept \noun default are evaluated first. This optional, \begin_inset Quotes eld \end_inset blanket \begin_inset Quotes erd \end_inset directive lets you specify that only certain things are to be accepted for logging, and everything else discarded. Because it is evaluated before \noun on LogSQLRequestIgnore \noun default and \noun on LogSQLRemhostIgnore \noun default it can halt logging before those two filtering directives \begin_inset Quotes eld \end_inset get their chance. \begin_inset Quotes erd \end_inset \layout Standard Once a request makes it past \noun on LogSQLRequestAccept \noun default , it still can be excluded based on \noun on LogSQLRemhostIgnore \noun default and \noun on LogSQLRequestIgnore \noun default . A good way to use \noun on LogSQLRemhostIgnore \noun default is to prevent the module from logging the traffic that your internal hosts generate. \noun on LogSQLRequestIgnore \noun default is great for preventing things like requests for \begin_inset Quotes eld \end_inset favicon.ico \begin_inset Quotes erd \end_inset from cluttering up your database, as well as excluding the various requests that worms make, etc. \layout Standard You can specify a series of strings after each directive. Do not use any type of globbing or regular-expression syntax -- each string is considered a match \emph on if it is a substring of the larger request or remote-host; the comarison is case-sensitive. \emph default This means that \noun on \begin_inset Quotes eld \end_inset LogSQLRemhostIgnore \noun default micro \begin_inset Quotes erd \end_inset will ignore requests from \begin_inset Quotes eld \end_inset microsoft.com, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset microworld.net, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset mymicroscope.org, \begin_inset Quotes erd \end_inset etc. \begin_inset Quotes eld \end_inset \noun on LogSQLRequestIgnore \noun default gif \begin_inset Quotes erd \end_inset will instruct the module to ignore requests for \begin_inset Quotes eld \end_inset leftbar.gif, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset bluedot.gif \begin_inset Quotes erd \end_inset and even \begin_inset Quotes eld \end_inset giftwrap.jpg \begin_inset Quotes erd \end_inset -- but \begin_inset Quotes eld \end_inset RED.GIF \begin_inset Quotes erd \end_inset and \begin_inset Quotes eld \end_inset Tree.Gif \begin_inset Quotes erd \end_inset would still get logged because of case sensitivity. \layout Standard A summary of the decision flow: \layout Enumerate If \noun on LogSQLRequestAccept \noun default exists and a request does not match anything in that list, it is discarded. \layout Enumerate If a request matches anything in the \noun on LogSQLRequestIgnore \noun default list, it is discarded. \layout Enumerate If a reqiest matches anything in the \noun on LogSQLRemhostIgnore \noun default list, it is discarded. \layout Enumerate Otherwise the request is logged. \layout Standard This means that you can have a series of directives similar to the following: \layout LyX-Code LogSQLRequestAccept *.html *.gif *.jpg \layout LyX-Code LogSQLRequestIgnore statistics.html bluedot.jpg \layout Standard So the first line instructs the module to \series bold only \series default log files with html, gif and jpg suffixes; requests for \begin_inset Quotes eld \end_inset formail.cgi \begin_inset Quotes erd \end_inset and \begin_inset Quotes eld \end_inset shopping-cart.pl \begin_inset Quotes erd \end_inset will never be considered for logging. ( \begin_inset Quotes eld \end_inset LeftArrow.JPG \begin_inset Quotes erd \end_inset will also never be considered for logging -- remember, the comparison is \series bold case sensitive \series default .) The second line prunes the list further -- you never want to log requests for those two objects. \layout Standard Tip: if you want to match all the hosts in your domain such as \begin_inset Quotes eld \end_inset host1.corp.foo.com \begin_inset Quotes srd \end_inset and \begin_inset Quotes eld \end_inset server.dmz.foo.com \begin_inset Quotes srd \end_inset , simply specify: \layout LyX-Code LogSQLRemhostIgnore foo.com \layout Standard Tip: a great way to catch the vast majority of worm-attack requests and prevent them from being logged is to specify: \layout LyX-Code LogSQLRequestIgnore root.exe cmd.exe default.ida \layout Standard Tip: to prevent the logging of requests for common graphic types, make sure to put a '.' before the suffix to avoid matches that you didn't intend: \layout LyX-Code LogSQLRequestIgnore .gif .jpg \layout Subsection Advanced logging scenarios \layout Subsubsection Using the module in an ISP environment \layout Standard mod_log_sql has three basic tiers of operation: \layout Enumerate The administrator creates all necessary tables by hand and configures each Apache VirtualHost by hand. ( \noun on LogSQLCreateTables Off \noun default ) \layout Enumerate The module is permitted to create necessary tables on-the-fly, but the administr ator configures each Apache VirtualHost by hand. ( \noun on LogSQLCreateTables On \noun default ) \layout Enumerate The module is permitted to create all necessary tables and to make intelligent, on-the-fly configuration of each VirtualHost. ( \noun on LogSQLMassVirtualHosting On \noun default ) \layout Standard Many users are happy to use the module in its most minimal form: they hand-creat e any necessary tables (using \begin_inset Quotes eld \end_inset create_tables.sql \begin_inset Quotes erd \end_inset ), and they configure each VirtualHost by hand to suit their needs. However, some administrators need extra features due to a large and growing number of VirtualHosts. The \noun on LogSQLMassVirtualHosting \noun default directive activates module capabilities that make it far easier to manage an ISP environment, or any situation characterized by a large and varying number of virtual servers: \layout Itemize the on-the-fly table creation feature is activated automatically \layout Itemize the transfer log table name is dynamically set from the virtual host's name (example: a virtual host \begin_inset Quotes eld \end_inset www.grubbybaby.com \begin_inset Quotes erd \end_inset gets logged to table \begin_inset Quotes eld \end_inset access_www_grubbybaby_com \begin_inset Quotes erd \end_inset ) \layout Standard There are numerous benefits. The admin will not need to create new tables for every new VirtualHost. (Although the admin will still need to drop the tables of virtual hosts that are removed.) The admin will not need to set \noun on LogSQLTransferLogTable \noun default for each virtual host -- it will be configured automatically based on the host's name. Because each virtual host will log to its own segregated table, data about one virtual server will segregate from others; an admin can grant users access to the tables they need, and they will be unable to view data about another user's virtual host. \layout Standard In an ISP scenario the admin is likely to have a cluster of many front-end webservers logging to a back-end database. mod_log_sql has a feature that permits analysis of how well the web servers are loadbalancing: the \noun on LogSQLMachineID \noun default directive. The administrator uses this directive to assign a unique identifier to each machine in the web cluster, e.g. \begin_inset Quotes eld \end_inset \noun on LogSQLMachineID \noun default web01, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset \noun on LogSQLMachineID \noun default web02, \begin_inset Quotes erd \end_inset etc. Used in conjunction with the 'M' character in \noun on LogSQLTransferLogFormat \noun default , each entry in the SQL log will include the machine ID of the machine that created the entry. This permits the administrator to count the entries made by each particular machine and thereby analyze the front-end loadbalancing algorithm. \layout Subsubsection \begin_inset LatexCommand \label{secMulTable} \end_inset Logging many-to-one data in separate tables \layout Standard A given HTTP request can have a one-to-many relationship with certain kinds of data. For example, a single HTTP request can have 4 cookies, 3 headers and 5 \begin_inset Quotes eld \end_inset mod_gzip \begin_inset Quotes erd \end_inset notes associated with it. mod_log_sql is capable of logging these relationships due to the elegance of SQL relational data. \layout Standard You already have a single table containing access requests. One of the columns in that table is 'id' which is intended to contain the unique request ID supplied by the standard Apache module mod_unique_id -- all you need to do is compile in that module and employ the \noun on LogSQLTransferLogFormat \noun default character 'I'. Thereafter, each request gets a unique ID that can be thought of as a primary key within the database, useful for joining multiple tables. So let's envision several new tables: a notes table, a cookies table, and a table for inbound and outbound headers. \layout Standard \begin_inset Float table wide false collapsed false \layout Caption \begin_inset LatexCommand \label{tblAcc} \end_inset access_log \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard id \end_inset \begin_inset Text \layout Standard remote_host \end_inset \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard time_stamp \end_inset \begin_inset Text \layout Standard status \end_inset \begin_inset Text \layout Standard bytes_sent \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard zerberus.aiacs.net \end_inset \begin_inset Text \layout Standard /mod_log_sql/index.html \end_inset \begin_inset Text \layout Standard 1022493617 \end_inset \begin_inset Text \layout Standard 200 \end_inset \begin_inset Text \layout Standard 2215 \end_inset \end_inset \end_inset \begin_inset Float table wide false collapsed false \layout Caption \begin_inset LatexCommand \label{tblNotes} \end_inset notes_log \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard id \end_inset \begin_inset Text \layout Standard item \end_inset \begin_inset Text \layout Standard val \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard mod_gzip_result \end_inset \begin_inset Text \layout Standard OK \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard mod_gzip_compression_ratio \end_inset \begin_inset Text \layout Standard 69 \end_inset \end_inset \end_inset \layout Standard \begin_inset Float table wide false collapsed false \layout Caption \begin_inset LatexCommand \label{tblHdr} \end_inset headers_log \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard id \end_inset \begin_inset Text \layout Standard item \end_inset \begin_inset Text \layout Standard val \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard Content-Type \end_inset \begin_inset Text \layout Standard text/html \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard Accept-Encoding \end_inset \begin_inset Text \layout Standard gzip, deflate \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard Expires \end_inset \begin_inset Text \layout Standard Tue, 28 May 2002 10:00:18 GMT \end_inset \begin_inset Text \layout Standard PPIDskBRH30AAGPtAsg \end_inset \begin_inset Text \layout Standard Cache-Control \end_inset \begin_inset Text \layout Standard max-age=86400 \end_inset \end_inset \end_inset \layout Standard We have a certain request, and its unique ID is \begin_inset Quotes eld \end_inset PPIDskBRH30AAGPtAsg \begin_inset Quotes erd \end_inset . Within each separate table will be multiple entries with that request ID: several cookie entries, several header entries, etc. As you can see in tables \begin_inset LatexCommand \ref{tblAcc} \end_inset , \begin_inset LatexCommand \ref{tblNotes} \end_inset and \begin_inset LatexCommand \ref{tblHdr} \end_inset , you have a one-to-many relationship for request PPIDskBRH30AAGPtAsg: that one access has two associated notes and four associated headers. You can extract this data easily using the power of SQL's \begin_inset Quotes eld \end_inset select \begin_inset Quotes erd \end_inset statement and table joins. To see the notes associated with a particular request: \layout LyX-Code select a.remote_host, a.request_uri, n.item, n.val from access_log a, notes_log n \layout LyX-Code where a.id=n.id and a.id='PPIDskBRH30AAGPtAsg'; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard remote_host \end_inset \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard item \end_inset \begin_inset Text \layout Standard val \end_inset \begin_inset Text \layout Standard zerberus.aiacs.net \end_inset \begin_inset Text \layout Standard /mod_log_sql/index.html \end_inset \begin_inset Text \layout Standard mod_gzip_result \end_inset \begin_inset Text \layout Standard OK \end_inset \begin_inset Text \layout Standard zerberus.aiacs.net \end_inset \begin_inset Text \layout Standard /mod_log_sql/index.html \end_inset \begin_inset Text \layout Standard mod_gzip_compression_ratio \end_inset \begin_inset Text \layout Standard 69 \end_inset \end_inset \layout LyX-Code \layout Standard Naturally you can craft similar statements for the outboud headers, inbound headers and cookies, all of which can live in separate tables. Your statements are limited in power only by your skill with SQL. \layout Standard In order to use this capability of mod_log_sql, you must do several things: \layout Itemize Compile mod_unique_id into Apache (statically or as a DSO). mod_log_sql employs the unique request ID that mod_unique_id provides in order to key between the separate tables. You can still log the data without mod_unqiue_id, but it will be completely uncorrelated and you will have no way to discern any meaning. \layout Itemize Create the appropriate tables. This will be done for you if you permit mod_log_sql to create its own tables using \noun on LogSQLCreateTables On \noun default , or if you use the enclosed \begin_inset Quotes eld \end_inset create_tables.sql \begin_inset Quotes erd \end_inset script. \layout Itemize Create a SQL index on the \begin_inset Quotes eld \end_inset id \begin_inset Quotes erd \end_inset column. Without this index, table joins will be deathly slow. I recommend you consult the MySQL documentation on the proper way to create a column index if you are not familiar with this operation. \layout Itemize Within each appropriate VirtualHost stanza, use the \noun on LogSQLWhich* \noun default and \noun on LogSQL*LogTable \noun default directives to tell the module what and where to log the data. In the following example, I have overridden the name for the notes table whereas I have left the other table names at their defaults. I have then specified the cookies, headers and notes that interest me. (And as you can see, these directives do not require me to add any characters to \noun on LogSQLTransferLogTable.) \layout LyX-Code \layout LyX-Code (snip) \layout LyX-Code LogSQLNotesLogTable notestable \layout LyX-Code LogSQLWhichCookies bluecookie redcookie greencookie \layout LyX-Code LogSQLWhichNotes mod_gzip_result mod_gzip_compression_ratio \layout LyX-Code LogSQLWhichHeadersOut Expires Content-Type Cache-Control \layout LyX-Code LogSQLWhichHeadersIn UserAgent Accept-Encoding Host \layout LyX-Code (snip) \layout LyX-Code \layout Subsubsection Using the same database for production and test \layout Standard Although suboptimal, it is not uncommon to use the same backend database for the \begin_inset Quotes eld \end_inset production \begin_inset Quotes erd \end_inset webservers as well as the \begin_inset Quotes eld \end_inset test \begin_inset Quotes erd \end_inset webservers (budgetary constraints, rackspace limits, etc.). Furthermore, an administrator in this situation may be unable to use \noun on LogSQLRemhostIgnore \noun default to exclude requests from the test servers -- perhaps the generated entries are genuinely useful for analytical or QA purposes, but their value after analysis is minimal. \layout Standard It is wasteful and potentially confusing to permit this internal test data to clutter the database, and a solution to the problem is the proper use of the \noun on LogSQLMachineID \noun default directive. Assume a scenario where the production webservers have IDs like \begin_inset Quotes eld \end_inset web01, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset web02, \begin_inset Quotes erd \end_inset and so on -- and the test webservers have IDs like \begin_inset Quotes eld \end_inset test01, \begin_inset Quotes erd \end_inset \begin_inset Quotes eld \end_inset test02, \begin_inset Quotes erd \end_inset etc. Because entries in the log database are distinguished by their source machine, an administrator may purge unneeded test data from the access log as follows: \layout LyX-Code delete from access_log where machine_id like 'test%'; \layout Subsubsection \begin_inset LatexCommand \label{sub:DelayedIns} \end_inset Optimizing for a busy database \layout Standard A busy MySQL database will have SELECT statements running concurrently with INSERT and UPDATE statements. A long-running SELECT can in certain circumstances block INSERTs and therefore block mod_log_sql. A workaround is to compile mod_log_sql for \begin_inset Quotes eld \end_inset delayed inserts, \begin_inset Quotes erd \end_inset which are described as follows in the MySQL documentation: \layout Quote The DELAYED option for the INSERT statement is a MySQL-specific option that is very useful if you have clients that can't wait for the INSERT to complete. This is a common problem when you use MySQL for logging and you also periodical ly run SELECT and UPDATE statements that take a long time to complete. DELAYED was introduced in MySQL Version 3.22.15. It is a MySQL extension to ANSI SQL92. \layout Quote INSERT DELAYED only works with ISAM and MyISAM tables. Note that as MyISAM tables supports concurrent SELECT and INSERT, if there is no free blocks in the middle of the data file, you very seldom need to use INSERT DELAYED with MyISAM. \layout Quote When you use INSERT DELAYED, the client will get an OK at once and the row will be inserted when the table is not in use by any other thread. \layout Quote Another major benefit of using INSERT DELAYED is that inserts from many clients are bundled together and written in one block. This is much faster than doing many separate inserts. \layout Standard The general disadvantages of delayed inserts are: \layout Enumerate The queued rows are only stored in memory until they are inserted into the table. If mysqld dies unexpectedly, any queued rows that weren't written to disk are lost. \layout Enumerate There is additional overhead for the server to handle a separate thread for each table on which you use INSERT DELAYED. \layout Standard \series bold The MySQL documentation concludes, \begin_inset Quotes eld \end_inset This means that you should only use INSERT DELAYED when you are really sure you need it! \begin_inset Quotes erd \end_inset Furthermore, the current state of error return from a failed INSERT DELAYED seems to be in flux, and may behave in unpredictable ways between different MySQL versions. See section \begin_inset LatexCommand \ref{sub:DelayedInsFAQ} \end_inset in the FAQ -- you have been warned. \layout Standard If you are experiencing issues which could be solved by delayed inserts, uncomment the #MYSQLDELAYED line in the Makefile by removing the # that is in front of it. Recompile and reinstall your module. All regular INSERT statements are now INSERT DELAYED, and you should see no more blocking of the module. \layout Subsection \begin_inset LatexCommand \label{sec:ConfRef} \end_inset Configuration directive reference \layout Standard It is imperative that you understand which directives are used \emph on only once \emph default in the main server config, and which are used inside VirtualHost stanzas and therefore multiple times within httpd.conf. The \begin_inset Quotes eld \end_inset context \begin_inset Quotes srd \end_inset listed with each entry informs you of this. \layout Subsubsection LogSQLCookieLogTable \layout LyX-Code Syntax: LogSQLCookieLogTable table-name \layout LyX-Code Example: LogSQLCookieLogTable cookie_log \layout LyX-Code Default: cookies \layout LyX-Code Context: virtual host \layout Standard Defines which table is used for logging of cookies. Working in conjunction with \noun on LogSQLWhichCookies \noun default , you can log many of each request's associated cookies to a separate table. For meaningful data retrieval the cookie table is keyed to the access table by the unique request ID supplied by the standard Apache module mod_unique_id. \layout Standard Note that you must create the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLCreateTables \layout LyX-Code Syntax: LogSQLCreateTables flag \layout LyX-Code Example: LogSQLCreateTables On \layout LyX-Code Default: Off \layout LyX-Code Context: main server config \layout Standard mod_log_sql has the ability to create its tables on-the-fly. The advantage to this is convenience: you don't have to execute any SQL by hand to prepare the table. This is especially helpful for people with lots of virtual hosts (who should also see the \noun on LogSQLMassVirtualHosting \noun default directive). \layout Standard There is a slight disadvantage: if you wish to activate this feature, then the userid specified in \noun on LogSQLLoginInfo \noun default must have CREATE privileges on the database. In an absolutely paranoid, locked-down situation you may only want to grant your mod_log_sql user INSERT privileges on the database; in that situation you are unable to take advantage of \noun on LogSQLCreateTables \noun default . But most people -- even the very security-conscious -- will find that granting CREATE on the logging database is reasonable. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLDatabase \layout LyX-Code \series bold MANDATORY \layout LyX-Code Syntax: LogSQLDatabase database \layout LyX-Code Example: LogSQLDatabase loggingdb \layout LyX-Code Context: main server config \layout Standard Defines the database that is used for logging. \begin_inset Quotes eld \end_inset database \begin_inset Quotes erd \end_inset must be a valid db on the MySQL host defined in \noun on LogSQLLoginInfo \noun default . \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLForcePreserve \layout LyX-Code Syntax: LogSQLForcePreserve Flag \layout LyX-Code Example: LogSQLPreserveFile on \layout LyX-Code Default: off \layout LyX-Code Context: main server config \layout Standard You may need to perform debugging on your database and specifically want mod_log_sql to make no attempts to log to it. This directive instructs the module to send all its log entries directly to the preserve file and to make no database INSERT attempts. \layout Standard This is presumably a directive for temporary use only; it could be dangerous if you set it and forget it, as all your entries will simply pile up in the preserve file. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLHeadersInLogTable \layout LyX-Code Syntax: LogSQLHeadersInLogTable table-name \layout LyX-Code Example: LogSQLHeadersInLogTable headers \layout LyX-Code Default: headers_in \layout LyX-Code Context: virtual host \layout Standard Defines which table is used for logging of inbound headers. Working in conjunction with \noun on LogSQLWhichHeadersIn \noun default , you can log many of each request's associated headers to a separate table. For meaningful data retrieval the headers table is keyed to the access table by the unique request ID supplied by the standard Apache module mod_uniqu e_id. \layout Standard Note that you must create the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLHeadersOutLogTable \layout LyX-Code Syntax: LogSQLHeadersOutLogTable table-name \layout LyX-Code Example: LogSQLHeadersOutLogTable headers \layout LyX-Code Default: headers_out \layout LyX-Code Context: virtual host \layout Standard Defines which table is used for logging of outbound headers. Working in conjunction with \noun on LogSQLWhichHeadersOut \noun default , you can log many of each request's associated headers to a separate table. For meaningful data retrieval the headers table is keyed to the access table by the unique request ID supplied by the standard Apache module mod_uniqu e_id. \layout Standard Note that you must create the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLLoginInfo \layout LyX-Code \series bold MANDATORY \series default \layout LyX-Code Syntax: LogSQLLoginInfo host user password \layout LyX-Code Example: LogSQLLoginInfo foobar.baz.com logwriter passw0rd \layout LyX-Code Context: main server config \layout Standard Defines the general parameters of the MySQL host to which you will be logging. \begin_inset Quotes eld \end_inset host \begin_inset Quotes erd \end_inset is the hostname or IP address of the MySQL machine, and is simply \begin_inset Quotes eld \end_inset localhost \begin_inset Quotes erd \end_inset if the database lives on the same machine as Apache. \begin_inset Quotes eld \end_inset user \begin_inset Quotes erd \end_inset is the MySQL userid (not a Unix userid!) with INSERT privileges on the table defined in \noun on LogSQLTransferLogTable \noun default . \begin_inset Quotes eld \end_inset password \begin_inset Quotes erd \end_inset is that user's password. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLMachineID \layout LyX-Code Syntax: LogSQLMachineID somename \layout LyX-Code Example: LogSQLMachineID web01 \layout LyX-Code Context: main server config \layout Standard If you have a farm of webservers then you may wish to know which particular machine made each entry; this is useful for analyzing your loadbalancing methodology. \noun on LogSQLMachineID \noun default permits you to distinguish each machine's entries if you assign each machine its own \noun on LogSQLMachineID \noun default : for example, the first webserver gets \begin_inset Quotes eld \end_inset \noun on LogSQLMachineID \noun default web01, \begin_inset Quotes erd \end_inset the second gets \begin_inset Quotes eld \end_inset \noun on LogSQLMachineID \noun default web02, \begin_inset Quotes erd \end_inset etc. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLMassVirtualHosting \layout LyX-Code Syntax: LogSQLMassVirtualHosting flag \layout LyX-Code Example: LogSQLMassVirtualHosting On \layout LyX-Code Default: Off \layout LyX-Code Context: main server config \layout Standard If you administer a site hosting many, many virtual hosts then this option will appeal to you. If you turn on \noun on LogSQLMassVirtualHosting \noun default then several things happen: \layout Itemize the on-the-fly table creation feature is activated automatically \layout Itemize the transfer log table name is dynamically set from the virtual host's name after stripping out SQL-unfriendly characters (example: a virtual host www.grubbybaby.com gets logged to table access_www_grubbybaby_com) \layout Itemize which, in turn, means that each virtual host logs to its own segregated table. Because there is no data shared between virtual servers you can grant your users access to the tables they need; they will be unable to view others' data. \layout Standard This is a huge boost in convenience for sites with many virtual servers. Activating \noun on LogSQLMassVirtualHosting \noun default obviates the need to create every virtual server's table and provides more granular security possibilities. \layout Standard You are advised to investigate the use of Apache's \noun on UseCanonicalName On \noun default directive with this directive in order to ensure that each virtual host maps to one table namespace. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLNotesLogTable \layout LyX-Code Syntax: LogSQLNotesLogTable table-name \layout LyX-Code Example: LogSQLNotesLogTable notes_log \layout LyX-Code Default: notes \layout LyX-Code Context: virtual host \layout Standard Defines which table is used for logging of notes. Working in conjunction with \noun on LogSQLWhichNotes \noun default , you can log many of each request's associated notes to a separate table. For meaningful data retrieval the notes table is keyed to the access table by the unique request ID supplied by the standard Apache module mod_unique_id. \layout Standard Note that you must create the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to ``on''. \layout Subsubsection LogSQLPreserveFile \layout LyX-Code Syntax: LogSQLPreserveFile filename \layout LyX-Code Example: LogSQLPreserveFile offline-preserve \layout LyX-Code Default: /tmp/sql-preserve \layout LyX-Code Context: virtual host \layout Standard mod_log_sql writes queries to this local preserve file in the event that it cannot reach the database, and thus ensures that your high-availability web frontend does not lose logs during a temporary database outage. This could happen for a number of reasons: the database goes offline, the network breaks, etc. You will not lose entries since the module has this backup. The file consists of a series of SQL statements that can be imported into your database at your convenience; furthermore, because the SQL queries contain the access timestamps you do not need to worry about out-of-order data after the import, which is done in a simple manner: \layout LyX-Code # mysql -uadminuser -p mydbname < /tmp/sql-preserve \layout Standard If you do not define \noun on LogSQLPreserveFile \noun default then all virtual servers will log to the same default preserve file (/tmp/sql-p reserve). You can redefine this on a virtual-host basis in order to segregate your preserve files if you desire. Note that segregation is not usually necessary, as the SQL statements that are written to the preserve file already distinguish between different virtual hosts if you include the 'v' character in your \noun on LogSQLTransferLogFormat \noun default directive. It is only necessary to segregate preserve-files by virualhost if you also segregate access logs by virtualhost. \layout Standard The module will log to Apache's \noun on ErrorLog \noun default when it notices a database outage, and upon database return. You will therefore know when the preserve file is being used, although it is your responsibility to import the file. \layout Standard The file does not need to be created in advance. It is safe to remove or rename the file without interrupting Apache, as the module closes the filehandle immediately after completing the write. The file is created with the user & group ID of the running Apache process (e.g. 'nobody' on many Linux distributions). \layout Subsubsection LogSQLRemhostIgnore \layout LyX-Code Syntax: LogSQLRemhostIgnore host1 host2 host3 ... hostN \layout LyX-Code Example: LogSQLRemhostIgnore localnet.com \layout LyX-Code Context: virtual host \layout Standard Lists a series of strings that, if present in the REMOTE_HOST, will cause that request to \series bold not \series default be logged. This directive is useful for cutting down on log clutter when you are certain that you want to ignore requests from certain hosts, such as your own internal network machines. See section \begin_inset LatexCommand \ref{sub:Ignore} \end_inset for some tips for using this directive. \layout Standard Each string is separated by a space, and no regular expressions or globbing are allowed. Each string is evaluated as a substring of the REMOTE_HOST using strstr(). The comparison is case sensitive. \layout Subsubsection LogSQLRequestAccept \layout LyX-Code Syntax: LogSQLRequestAccept req1 req2 req3 ... reqN \layout LyX-Code Example: LogSQLRequestAccept .html .php .jpg \layout LyX-Code Default: if not specified, all requests are \begin_inset Quotes eld \end_inset accepted \begin_inset Quotes erd \end_inset \layout LyX-Code Context: virtual host \layout Standard Lists a series of strings that, if present in the URI, will permit that request to be \series bold \series default considered for logging (depending on additional filtering by the \begin_inset Quotes eld \end_inset ignore \begin_inset Quotes erd \end_inset directives). Any request that fails to match one of the \noun on LogSQLRequestAccept \noun default entries will be discarded. \layout Standard This directive is useful for cutting down on log clutter when you are certain that you only want to log certain kinds of requests, and just blanket-ignore everything else. See section \begin_inset LatexCommand \ref{sub:Ignore} \end_inset for some tips for using this directive. \layout Standard Each string is separated by a space, and no regular expressions or globbing are allowed. Each string is evaluated as a substring of the URI using strstr(). The comparison is case sensitive. \layout Standard This directive is completely optional. It is more general than \noun on LogSQLRequestIgnore \noun default and \noun on \noun default is evaluated before \noun on LogSQLRequestIgnore \noun default . If this directive is not used, \series bold all \series default requests are accepted and passed on to the other filtering directives. Therefore, only use this directive if you have a specific reason to do so. \layout Subsubsection LogSQLRequestIgnore \layout LyX-Code Syntax: LogSQLRequestIgnore req1 req2 req3 ... reqN \layout LyX-Code Example: LogSQLRequestIgnore root.exe cmd.exe default.ida favicon.ico \layout LyX-Code Context: virtual host \layout Standard Lists a series of strings that, if present in the URI, will cause that request to \series bold NOT \series default be \series bold \series default logged. This directive is useful for cutting down on log clutter when you are certain that you want to ignore requests for certain objects. See section \begin_inset LatexCommand \ref{sub:Ignore} \end_inset for some tips for using this directive. \layout Standard Each string is separated by a space, and no regular expressions or globbing are allowed. Each string is evaluated as a substring of the URI using strstr(). The comparison is case sensitive. \layout Subsubsection LogSQLSocketFile \layout LyX-Code Syntax: LogSQLSocketFile filename \layout LyX-Code Example: LogSQLSocketFile /tmp/mysql.sock \layout LyX-Code Default: /var/lib/mysql/mysql.sock \layout LyX-Code Context: main server config \layout Standard At Apache runtime you can specify the MySQL socket file to use. Set this once in your main server config to override the default value. This value is irrelevant if your database resides on a separate machine. \layout Standard mod_log_sql will automatically employ the socket for db communications if the database resides on the local host. If the db resides on a separate host the module will automatically use TCP/IP. This is a function of the MySQL API and is not user-configurable. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection LogSQLTCPPort \layout LyX-Code Syntax: LogSQLTCPPort portnumber \layout LyX-Code Example: LogSQLTCPPort 3309 \layout LyX-Code Default: 3306 \layout LyX-Code Context: main server config \layout Standard Your database may listen on a different port than the default. If so, use this directive to instruct the module which port to use. This directive only applies if the database is on a different machine connected via TCP/IP. \layout Standard This is defined only once in the httpd.conf file. \layout Subsubsection \begin_inset LatexCommand \label{sub:Frmat} \end_inset LogSQLTransferLogFormat \layout LyX-Code Syntax: LogSQLTransferLogFormat format-string \layout LyX-Code Example: LogSQLTransferLogFormat huSUTv \layout LyX-Code Default: AbHhmRSsTUuv \layout LyX-Code Context: virtual host \layout Standard Each character in the format-string defines an attribute of the request that you wish to log. The default logs the information required to create Combined Log Format logs, plus several extras. Here is the full list of allowable keys, which sometimes resemble their Apache counterparts, but do not always: \layout Quote \size footnotesize \begin_inset Tabular \begin_inset Text \layout Standard \end_inset \begin_inset Text \layout Standard \series bold \size footnotesize What is this? \end_inset \begin_inset Text \layout Standard \series bold \size footnotesize Data field \end_inset \begin_inset Text \layout Standard \series bold \size footnotesize Column type \end_inset \begin_inset Text \layout Standard \series bold \size footnotesize Example \end_inset \begin_inset Text \layout Standard \size footnotesize A \end_inset \begin_inset Text \layout Standard \size footnotesize User agent \end_inset \begin_inset Text \layout Standard \size footnotesize agent \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(255) \end_inset \begin_inset Text \layout Standard \size footnotesize Mozilla/4.0 (compat; MSIE 6.0; Windows) \end_inset \begin_inset Text \layout Standard a \end_inset \begin_inset Text \layout Standard CGI request arguments \end_inset \begin_inset Text \layout Standard request_args \end_inset \begin_inset Text \layout Standard varchar(255) \end_inset \begin_inset Text \layout Standard user=Smith&cart=1231&item=532 \end_inset \begin_inset Text \layout Standard \size footnotesize b \end_inset \begin_inset Text \layout Standard \size footnotesize Bytes transfered \end_inset \begin_inset Text \layout Standard \size footnotesize bytes_sent \end_inset \begin_inset Text \layout Standard \size footnotesize int unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 32561 \end_inset \begin_inset Text \layout Standard \size footnotesize c \end_inset \begin_inset Text \layout Standard \size footnotesize Text of cookie \begin_inset Formula $^{\textrm{1}}$ \end_inset \end_inset \begin_inset Text \layout Standard \size footnotesize cookie \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(255) \end_inset \begin_inset Text \layout Standard \size footnotesize Apache=sdyn.fooonline.net.1300102700823 \end_inset \begin_inset Text \layout Standard \size footnotesize H \end_inset \begin_inset Text \layout Standard \size footnotesize HTTP request protocol \end_inset \begin_inset Text \layout Standard \size footnotesize request_protocol \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(10) \end_inset \begin_inset Text \layout Standard \size footnotesize HTTP/1.1 \end_inset \begin_inset Text \layout Standard \size footnotesize h \end_inset \begin_inset Text \layout Standard \size footnotesize Name of remote host \end_inset \begin_inset Text \layout Standard \size footnotesize remote_host \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(50) \end_inset \begin_inset Text \layout Standard \size footnotesize blah.foobar.com \end_inset \begin_inset Text \layout Standard \size footnotesize I \end_inset \begin_inset Text \layout Standard \size footnotesize Request ID (from mod_unique_id) \end_inset \begin_inset Text \layout Standard \size footnotesize id \end_inset \begin_inset Text \layout Standard \size footnotesize char(19) \end_inset \begin_inset Text \layout Standard \size footnotesize POlFcUBRH30AAALdBG8 \end_inset \begin_inset Text \layout Standard \size footnotesize l \end_inset \begin_inset Text \layout Standard \size footnotesize Ident user info \end_inset \begin_inset Text \layout Standard \size footnotesize remote_logname \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(50) \end_inset \begin_inset Text \layout Standard \size footnotesize bobby \end_inset \begin_inset Text \layout Standard \size footnotesize M \end_inset \begin_inset Text \layout Standard \size footnotesize Machine ID \begin_inset Formula $^{\textrm{2}}$ \end_inset \end_inset \begin_inset Text \layout Standard \size footnotesize machine_id \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(25) \end_inset \begin_inset Text \layout Standard \size footnotesize web01 \end_inset \begin_inset Text \layout Standard \size footnotesize m \end_inset \begin_inset Text \layout Standard \size footnotesize HTTP request method \end_inset \begin_inset Text \layout Standard \size footnotesize request_method \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(6) \end_inset \begin_inset Text \layout Standard \size footnotesize GET \end_inset \begin_inset Text \layout Standard \size footnotesize P \end_inset \begin_inset Text \layout Standard \size footnotesize httpd child PID \end_inset \begin_inset Text \layout Standard \size footnotesize child_pid \end_inset \begin_inset Text \layout Standard \size footnotesize smallint unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 3215 \end_inset \begin_inset Text \layout Standard \size footnotesize p \end_inset \begin_inset Text \layout Standard \size footnotesize httpd port \end_inset \begin_inset Text \layout Standard \size footnotesize server_port \end_inset \begin_inset Text \layout Standard \size footnotesize smallint unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 80 \end_inset \begin_inset Text \layout Standard \size footnotesize R \end_inset \begin_inset Text \layout Standard \size footnotesize Referer \end_inset \begin_inset Text \layout Standard \size footnotesize referer \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(255) \end_inset \begin_inset Text \layout Standard \size footnotesize http://www.biglinks4u.com/linkpage.html \end_inset \begin_inset Text \layout Standard \size footnotesize r \end_inset \begin_inset Text \layout Standard \size footnotesize Request in full form \end_inset \begin_inset Text \layout Standard \size footnotesize request_line \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(255) \end_inset \begin_inset Text \layout Standard \size footnotesize GET /books-cycroad.html HTTP/1.1 \end_inset \begin_inset Text \layout Standard \size footnotesize S \end_inset \begin_inset Text \layout Standard \size footnotesize Time of request in UNIX format \end_inset \begin_inset Text \layout Standard \size footnotesize time_stamp \end_inset \begin_inset Text \layout Standard \size footnotesize int unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 1005598029 \end_inset \begin_inset Text \layout Standard \size footnotesize s \end_inset \begin_inset Text \layout Standard \size footnotesize HTTP status of request \end_inset \begin_inset Text \layout Standard \size footnotesize status \end_inset \begin_inset Text \layout Standard \size footnotesize smallint unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 404 \end_inset \begin_inset Text \layout Standard \size footnotesize T \end_inset \begin_inset Text \layout Standard \size footnotesize Seconds to service request \end_inset \begin_inset Text \layout Standard \size footnotesize request_duration \end_inset \begin_inset Text \layout Standard \size footnotesize smallint unsigned \end_inset \begin_inset Text \layout Standard \size footnotesize 2 \end_inset \begin_inset Text \layout Standard \size footnotesize t \end_inset \begin_inset Text \layout Standard \size footnotesize Time of request in human format \end_inset \begin_inset Text \layout Standard \size footnotesize request_time \end_inset \begin_inset Text \layout Standard \size footnotesize char(28) \end_inset \begin_inset Text \layout Standard \size footnotesize [02/Dec/2001:15:01:26 -0800] \end_inset \begin_inset Text \layout Standard \size footnotesize U \end_inset \begin_inset Text \layout Standard \size footnotesize Request in simple form \end_inset \begin_inset Text \layout Standard \size footnotesize request_uri \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(255) \end_inset \begin_inset Text \layout Standard \size footnotesize /books-cycroad.html \end_inset \begin_inset Text \layout Standard \size footnotesize u \end_inset \begin_inset Text \layout Standard \size footnotesize User info from HTTP auth \end_inset \begin_inset Text \layout Standard \size footnotesize remote_user \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(50) \end_inset \begin_inset Text \layout Standard \size footnotesize bobby \end_inset \begin_inset Text \layout Standard \size footnotesize v \end_inset \begin_inset Text \layout Standard \size footnotesize Virtual host servicing the request \end_inset \begin_inset Text \layout Standard \size footnotesize virtual_host \end_inset \begin_inset Text \layout Standard \size footnotesize varchar(50) \end_inset \begin_inset Text \layout Standard \size footnotesize www.foobar.com \end_inset \end_inset \layout Quote \begin_inset Formula $^{\textrm{1}}$ \end_inset You must also specify \noun on LogSQLWhichCookie \noun default for this to take effect. \layout Quote \begin_inset Formula $^{\textrm{2}}$ \end_inset You must also specify \noun on LogSQLMachineID \noun default for this to take effect. \layout Standard If you have compiled mod_log_sql with SSL logging capability, you also can use these: \layout Quote \begin_inset Tabular \begin_inset Text \layout Standard \end_inset \begin_inset Text \layout Standard \series bold What is this? \end_inset \begin_inset Text \layout Standard \series bold Data field \end_inset \begin_inset Text \layout Standard \series bold Column Type \end_inset \begin_inset Text \layout Standard \series bold Example \end_inset \begin_inset Text \layout Standard z \end_inset \begin_inset Text \layout Standard SSL cipher used \end_inset \begin_inset Text \layout Standard ssl_cipher \end_inset \begin_inset Text \layout Standard varchar(25) \end_inset \begin_inset Text \layout Standard RC4-MD5 \end_inset \begin_inset Text \layout Standard q \end_inset \begin_inset Text \layout Standard Keysize of the SSL connection \end_inset \begin_inset Text \layout Standard ssl_keysize \end_inset \begin_inset Text \layout Standard smallint unsigned \end_inset \begin_inset Text \layout Standard 56 \end_inset \begin_inset Text \layout Standard Q \end_inset \begin_inset Text \layout Standard Maximum keysize supported \end_inset \begin_inset Text \layout Standard ssl_maxkeysize \end_inset \begin_inset Text \layout Standard smallint unsigned \end_inset \begin_inset Text \layout Standard 128 \end_inset \end_inset \layout Subsubsection LogSQLTransferLogTable \layout LyX-Code \series bold MANDATORY (unless \noun on LogSQLMassVirtualHosting \noun default is \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset ) \layout LyX-Code Syntax: LogSQLTransferLogTable table-name \layout LyX-Code Example: LogSQLTransferLogTable access_log_table \layout LyX-Code Context: virtual host \layout Standard Defines which table is used for logging of Apache's transfers; this is analogous to Apache's TransferLog directive. table-name must be a valid table within the database defined in \noun on LogSQLDatabase \noun default . \layout Standard This directive is not necessary if you declare \noun on LogSQLMassVirtualHosting On \noun default , since that directive activates dynamically-named tables. If you attempt to use \noun on LogSQLTransferLogTable \noun default at the same time a warning will be logged and it will be ignored, since \noun on LogSQLMassVirtualHosting \noun default takes priority. \layout Subsubsection LogSQLWhichCookie \layout LyX-Code Syntax: LogSQLWhichCookie cookiename \layout LyX-Code Example: LogSQLWhichCookie Clicks \layout LyX-Code Default: None \layout LyX-Code Context: virtual host \layout Standard In HTTP, cookies have names to distinguish them from each other. Using mod_usertrack, for example, you can give your user-tracking cookies a name with the CookieName directive. \layout Standard mod_log_sql allows you to log cookie information. \noun on LogSQLWhichCookie \noun default tells mod_log_sql which cookie to log. This is necessary because you will usually be setting and receiving more than one cookie from a client. \layout Standard You must include a 'c' character in \noun on LogSQLTransferLogFormat \noun default for this directive to take effect. \layout Standard Note: although this was origintally intended for people using mod_usertrack to create user-tracking cookies, you aren't restricted in any way. You can choose which cookie you wish to log to the database -- any cookie at all -- and it doesn't necessarily have to have anything to do with mod_usert rack. \layout Subsubsection LogSQLWhichCookies \layout LyX-Code Syntax: LogSQLWhichCookies cookie1 cookie2 ... cookieN \layout LyX-Code Example: LogSQLWhichCookies userlogin foobar foobaz \layout LyX-Code Default: None \layout LyX-Code Context: virtual host \layout Standard Defines the list of cookies you would like logged. This works in conjunction with \noun on LogSQLCookieLogTable \noun default . This directive does not require any additional characters to be added to the \noun on LogSQLTransferLogFormat \noun default string. The feature is activated simply by including this directive, upon which you will begin populating the separate cookie table with data. \layout Standard Note that you must have already created the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLWhichHeadersIn \layout LyX-Code Syntax: LogSQLWhichHeadersIn item1 item2 ... itemN \layout LyX-Code Example: LogSQLWhichHeadersIn UserAgent Accept-Encoding Host \layout LyX-Code Default: None \layout LyX-Code Context: virtual host \layout Standard Defines the list of inbound headers you would like logged. This works in conjunction with \noun on LogSQLHeadersInLogTable \noun default . This directive does not require any additional characters to be added to the \noun on LogSQLTransferLogFormat \noun default string. The feature is activated simply by including this directive, upon which you will begin populating the separate inbound-headers table with data. \layout Standard Note that you must have already created the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLWhichHeadersOut \layout LyX-Code Syntax: LogSQLWhichHeadersOut item1 item2 ... itemN \layout LyX-Code Example: LogSQLWhichHeadersOut Expires Content-Type Cache-Control \layout LyX-Code Default: None \layout LyX-Code Context: virtual host \layout Standard Defines the list of outbound headers you would like logged. This works in conjunction with \noun on LogSQLHeadersOutLogTable \noun default . This directive does not require any additional characters to be added to the \noun on LogSQLTransferLogFormat \noun default string. The feature is activated simply by including this directive, upon which you will begin populating the separate outbound-headers table with data. \layout Standard Note that you must have already created the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Subsubsection LogSQLWhichNotes \layout LyX-Code Syntax: LogSQLWhichNotes item1 item2 ... itemN \layout LyX-Code Example: LogSQLWhichNotes mod_gzip_result mod_gzip_compression_ratio \layout LyX-Code Default: None \layout LyX-Code Context: virtual host \layout Standard Defines the list of notes you would like logged. This works in conjunction with \noun on LogSQLNotesLogTable \noun default . This directive does not require any additional characters to be added to the \noun on LogSQLTransferLogFormat \noun default string. The feature is activated simply by including this directive, upon which you will begin populating the separate notes table with data. \layout Standard Note that you must have already created the table (see create-tables.sql, included in the package), or \noun on LogSQLCreateTables \noun default must be set to \begin_inset Quotes eld \end_inset on \begin_inset Quotes erd \end_inset . \layout Section FAQ \layout Subsection General module questions \layout Subsubsection \begin_inset LatexCommand \label{sub:why} \end_inset Why log to an SQL database? \layout Standard To begin with, let's get it out of the way: logging to a database is not a panacea. But while there are complexities with this solution, the benefit can be substantial for certain classes of administrator or people with advanced requirements: \layout Itemize Chores like log rotation go away, as you can DELETE records from the SQL database once they are no longer useful. For example, the excellent and popular log-analysis tool \begin_inset LatexCommand \url[Webalizer]{(http://www.webalizer.com)} \end_inset does not need historic logs after it has processed them, enabling you to delete older logs. \layout Itemize People with clusters of web servers (for high availability) will benefit the most -- all their webservers can log to a single SQL database. This obviates the need to collate/interleave the many separate logfiles, which can be / highly/ problematic. \layout Itemize People acquainted with the power of SQL SELECT statements will know the flexibility of the extraction possibilities at their fingertips. \layout Standard For example, do you want to see all your 404's? Do this: \layout LyX-Code select remote_host,status,request_uri,bytes_sent,from_unixtime(time_stamp) \layout LyX-Code from acc_log_tbl where status=404 order by time_stamp; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard remote_host \end_inset \begin_inset Text \layout Standard status \end_inset \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard bytes_sent \end_inset \begin_inset Text \layout Standard from_unixtime(time_stamp) \end_inset \begin_inset Text \layout Standard marge.mmm.co.uk \end_inset \begin_inset Text \layout Standard 404 \end_inset \begin_inset Text \layout Standard /favicon.ico \end_inset \begin_inset Text \layout Standard 321 \end_inset \begin_inset Text \layout Standard 2001-11-20 02:30:56 \end_inset \begin_inset Text \layout Standard 62.180.239.251 \end_inset \begin_inset Text \layout Standard 404 \end_inset \begin_inset Text \layout Standard /favicon.ico \end_inset \begin_inset Text \layout Standard 333 \end_inset \begin_inset Text \layout Standard 2001-11-20 02:45:25 \end_inset \begin_inset Text \layout Standard 212.234.12.66 \end_inset \begin_inset Text \layout Standard 404 \end_inset \begin_inset Text \layout Standard /favicon.ico \end_inset \begin_inset Text \layout Standard 321 \end_inset \begin_inset Text \layout Standard 2001-11-20 03:01:00 \end_inset \begin_inset Text \layout Standard 212.210.78.254 \end_inset \begin_inset Text \layout Standard 404 \end_inset \begin_inset Text \layout Standard /favicon.ico \end_inset \begin_inset Text \layout Standard 333 \end_inset \begin_inset Text \layout Standard 2001-11-20 03:26:05 \end_inset \end_inset \layout LyX-Code \layout Standard Or do you want to see how many bytes you've sent within a certain directory or site? Do this: \layout LyX-Code select request_uri,sum(bytes_sent) as bytes,count(request_uri) as howmany from \layout LyX-Code acc_log_tbl where request_uri like '%mod_log_sql%' group by request_uri order \layout LyX-Code by howmany desc; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard bytes \end_inset \begin_inset Text \layout Standard howmany \end_inset \begin_inset Text \layout Standard /mod_log_sql/style_1.css \end_inset \begin_inset Text \layout Standard 157396 \end_inset \begin_inset Text \layout Standard 1288 \end_inset \begin_inset Text \layout Standard /mod_log_sql/ \end_inset \begin_inset Text \layout Standard 2514337 \end_inset \begin_inset Text \layout Standard 801 \end_inset \begin_inset Text \layout Standard /mod_log_sql/mod_log_sql.tar.gz \end_inset \begin_inset Text \layout Standard 9769312 \end_inset \begin_inset Text \layout Standard 456 \end_inset \begin_inset Text \layout Standard /mod_log_sql/faq.html \end_inset \begin_inset Text \layout Standard 5038728 \end_inset \begin_inset Text \layout Standard 436 \end_inset \end_inset \layout LyX-Code \layout Standard Or maybe you want to see who's linking to you? Do this: \layout LyX-Code select count(referer) as num,referer from acc_log_tbl where \layout LyX-Code request_uri='/mod_log_sql/' group by referer order by num desc; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard num \end_inset \begin_inset Text \layout Standard referer \end_inset \begin_inset Text \layout Standard 271 \end_inset \begin_inset Text \layout Standard http://freshmeat.net/projects/mod_log_sql/ \end_inset \begin_inset Text \layout Standard 96 \end_inset \begin_inset Text \layout Standard http://modules.apache.org/search?id=339 \end_inset \begin_inset Text \layout Standard 48 \end_inset \begin_inset Text \layout Standard http://freshmeat.net/ \end_inset \begin_inset Text \layout Standard 8 \end_inset \begin_inset Text \layout Standard http://freshmeat.net \end_inset \end_inset \layout LyX-Code \layout Standard As you can see, there are myriad possibilities that can be constructed with the wonderful SQL SELECT statement. Logging to an SQL database can be really quite useful! \layout Subsubsection Why use MySQL? Are there alternatives? \layout Standard MySQL is a robust, free, and very powerful production-quality database engine. It is well supported and comes with detailed documentation. Many 3rd-party software pacakges (e.g. Slashcode, the engine that powers Slashdot) run exclusively with MySQL. In other words, you will belong to a very robust and well-supported community by choosing MySQL. \layout Standard That being said, there are alternatives. PostgreSQL is probably MySQL's leading "competitor" in the free database world. There is also an excellent module available for Apache to permit logging to a PostgreSQL database, called \begin_inset LatexCommand \url[pgLOGd]{(http://www.digitalstratum.com/pglogd/)} \end_inset . \layout Subsubsection Is this code production-ready? \layout Standard By all accounts it is. It is known to work without a problem on many-thousands-of-hits-per-day webservers. Does that mean it is 100% bug free? Well, no software is. But it is well-tested and believed to be fully compatible with production environments. (The usual disclaimers apply. This software is provided without warranty of any kind.) \layout Subsubsection Who's using mod_log_sql? \layout Standard Good question! It would be great to find out! If you are a production-level mod_log_sql user, please contact \begin_inset LatexCommand \url[the maintainer, Chris Powell]{(chris@grubbybaby.com)} \end_inset so that you can be mentioned here. \layout Subsubsection Why doesn't the module also replace the Apache ErrorLog? \layout Standard There are circumstances when that would be quite unwise -- for example, if Apache could not reach the MySQL server for some reason and needed to log that fact. Without a text-based error log you'd never know anything was wrong, because Apache would be trying to log a database connection error to the database... you get the point. \layout Standard Error logs are usually not very high-traffic and are really best left as text files on a web server machine. \layout Subsubsection Does mod_log_sql work with Apache 2.x? \layout Standard As of this writing, no. The Apache Group significantly altered the module API with the release of Apache 2.0. All modules written for 1.3, including mod_log_sql, will not work with 2.0. \layout Standard mod_log_sql will eventually be ported to Apache 2.x, but not immediately. It is going to take some time, and there are other features that have higher priority. Please sign up for the announcements list (on the main website) or monitor the website for updates to learn when the port (and other releases) are available. \layout Standard If you're a *NIX user, stick with Apache 1.3.x for now. Major modules like mod_ssl and PHP are not even ready for 2.0 yet, and the main benefits in 2.0 are for Win32 users anyway. Apache 1.3.x is rock-stable and performs equally well on *NIX as 2.0. \layout Subsubsection Does mod_log_sql connect to MySQL via TCP/IP or a socket? \layout Standard It depends! This is not determined by mod_log_sql. mod_log_sql relies on a connection command that is supplied in the MySQL API, and that command is somewhat intelligent. How it works: \layout Itemize if the specified MySQL database is on the same machine, the connection command uses a socket to communicate with MySQL \layout Itemize if the specified MySQL database is on a different machine, mod_log_sql connects using TCP/IP. \layout Standard You don't have any control of which methodology is used. You can fine-tune some of the configuration, however. The \noun on LogSQLSocketFile \noun default runtime configuration directive overrides the default of \begin_inset Quotes eld \end_inset /var/lib/mysql/mysql.sock \begin_inset Quotes erd \end_inset for socket-based connections, whereas the \noun on LogSQLTCPPort \noun default command allows to you override the default TCP port of 3306 for TCP/IP connections. \layout Subsubsection I have discovered a bug. Who can I contact? \layout Standard Please contact \begin_inset LatexCommand \url[the maintainer]{(chris@grubbybaby.com)} \end_inset ! Your comments, suggestions, bugfixes, bug catches, and usage testimonials are always welcome. As free software, mod_log_sql is intended to be a community effort -- any code contributions or other ideas will be fully and openly credited, of course. \layout Subsection Problems \layout Subsubsection Apache segfaults or has other problems when using PHP and mod_log_sql \layout Standard This occurs if you compiled PHP with MySQL database support. PHP utilizes its internal, bundled MySQL libraries by default. These conflict with the \begin_inset Quotes eld \end_inset real \begin_inset Quotes erd \end_inset MySQL libraries linked by mod_log_sql, causing the segmentation fault. \layout Standard PHP and mod_log_sql can be configured to happily coexist. The solution is to configure PHP to link against the real MySQL libraries: recompile PHP using --with-mysql=/your/path. Apache will run properly once the modules are all using the same version of the MySQL libraries. \layout Subsubsection \begin_inset LatexCommand \label{faq:NothingLogged} \end_inset Apache appears to start up fine, but nothing is getting logged in the database \layout Standard If you do not see any entries in the access_log, then something is preventing the inserts from happening. This could be caused by several things: \layout Itemize Improper privileges set up in the MySQL database \layout Itemize You aren't hitting a VirtualHost that has a LogSQLTransferLogTable entry \layout Itemize You didn't specify the right database host or login information \layout Itemize Another factor is preventing a connection to the database \layout Standard Important: it is improper to ask for help before you have followed these steps. \layout Standard First examine the MySQL log that you established in step \begin_inset LatexCommand \ref{step:EnaLog} \end_inset of section \begin_inset LatexCommand \ref{sub:PrepDb} \end_inset . Ensure that the INSERT statements are not being rejected because of a malformed table name or other typographical error. By enabling that log, you instructed MySQL to log every connection and command it receives -- if you see no INSERT attempts in the log, the module isn't successfully connecting to the database. If you see nothing at all in the log -- not even a record of your administrativ e connection attempts, then you did not enable the log correctly. If you do see INSERT attempts but they are failing, the log should tell you why. \layout Standard Second, confirm that your \noun on LogSQL* \noun default directives are all correct. \layout Standard Third, examine the Apache \noun on \noun default error logs for messages from mod_log_sql; the module will offer hints as to why it cannot connect, etc. \layout Standard The next thing to do is recompile the module with debugging output activated. change the "#undef DEBUG" on line 8 of mod_log_sql.c to "#define DEBUG" and recompile/reinstall. The module will now output copious notes about what it is doing, and this will help you (and the maintainer) solve the problem. In order to see the debugging messages, ensure that you make them visible using the \noun on LogLevel \noun default directive \series bold in the main server config as well as in each \noun on VirtualHost \noun default config: \layout LyX-Code LogLevel debug \layout LyX-Code ErrorLog /var/log/httpd/server-messages \layout Subsubsection Why do I get the message \begin_inset Quotes eld \end_inset insufficient configuration info to establish database link \begin_inset Quotes erd \end_inset in my Apache error log? \layout Standard At a minimum, \noun on LogSQLDatabase \noun default and \noun on LogSQLLoginInfo \noun default must be defined in order for the module to be able to establish a database link. If these are not defined or are incomplete you will receive this error message. \layout Subsubsection My database cannot handle all the open connections from mod_log_sql, is there anything I can do? \layout Standard The rule of thumb: if you have \emph on n \emph default webservers each configured to support \emph on y \emph default \noun on MaxClients \noun default , then your database must be able to handle \begin_inset Formula $n\times y$ \end_inset simultenous connections \emph on in the worst case. \emph default Certainly you must use common sense, consider reasonable traffic expectations and structure things accordingly. \layout Standard Tweaking my.cnf to scale to high connection loads is imperative. But if hardware limitations prevent your MySQL server from gracefully handling the number of incoming connections, it would be beneficial to upgrade the memory or CPU on that server in order to handle the load. \layout Standard Jeremy Zawodny, a highly respected MySQL user and contributor to Linux Magazine, has this very helpful and highly appropriate article on tuning MySQL: \begin_inset LatexCommand \url{http://jeremy.zawodny.com/blog/archives/000173.html} \end_inset \layout Standard Please remember that mod_log_sql's overriding principle is \series bold performance \series default -- that is what the target audience demands and expects. Other database logging solutions do not open and maintain many database connections, but their performance suffers drastically. For example, pgLOGd funnels all log connections through a separate daemon that connects to the database, but that bottlenecks the entire process. mod_log_sql achieves performance numbers an order of magnitude greater than the alternatives because it dispenses with the overhead associated with rapid connection cycling, and it doesn't attempt to shoehorn all the database traffic through a single extra daemon or proxy process. \layout Subsubsection Why do I occasionally see a \begin_inset Quotes eld \end_inset lost connection to MySQL server \begin_inset Quotes erd \end_inset message in my Apache error log? \layout Standard This message may appear every now and then in your Apache error log, especially on very lightly loaded servers. This doesn't mean that anything is necessarily wrong. Within each httpd child process, mod_log_sql will open (and keep open) a connection to the MySQL server. MySQL, however, will close connections that haven't been used in a while; the default timeout is 8 hours. When this occurs, mod_log_sql will notice and re-open the connection. That event is what is being logged, and looks like this: \layout LyX-Code [Tue Nov 12 19:04:10 2002] [error] mod_log_sql: first attempt failed, \layout LyX-Code API said: error 2013, Lost connection to MySQL server during query \layout LyX-Code [Tue Nov 12 19:04:10 2002] [error] mod_log_sql: reconnect successful \layout LyX-Code [Tue Nov 12 19:04:10 2002] [error] mod_log_sql: second attempt successful \layout Standard Reference: \begin_inset LatexCommand \url[MySQL documentation]{(http://www.mysql.com/documentation/mysql/bychapter/manual_Problems.html#Gone_away)} \end_inset \layout Subsubsection Sometimes a single VirtualHost gets logged to two different tables (e.g. access_foo_com, access_www_foo_com). Or, accesses to an unqualified hostname (e.g. \begin_inset Quotes eld \end_inset http://intranet/index.html \begin_inset Quotes erd \end_inset ) get logged in separate tables. \layout Standard Proper usage of the Apache runtime \noun on ServerName \noun default directive and the directive \noun on UseCanonicalName On \noun default (or \noun on DNS \noun default ) are necessary to prevent this problem. \begin_inset Quotes eld \end_inset On \begin_inset Quotes erd \end_inset is the default for \noun on UseCanonicalName \noun default , and specifies that self-referential URLs are generated from the \noun on ServerName \noun default part of your VirtualHost: \layout Quote With UseCanonicalName on (and in all versions prior to 1.3) Apache will use the ServerName and Port directives to construct the canonical name for the server. With UseCanonicalName off Apache will form self-referential URLs using the hostname and port supplied by the client if any are supplied (otherwise it will use the canonical name, as defined above). [From \begin_inset LatexCommand \url[the Apache documentation]{http://httpd.apache.org/docs/mod/core.html#usecanonicalname} \end_inset ] \layout Standard The module inherits Apache's \begin_inset Quotes eld \end_inset knowledge \begin_inset Quotes erd \end_inset about the server name being accessed. As long as those two directives are properly configured, mod_log_sql will log to only one table per virtual host while using \noun on LogSQLMassVirtualHosting \noun default . \layout Subsection Performance and Tuning \layout Subsubsection How well does it perform? \layout Standard mod_log_sql scales to very high loads. Apache 1.3.22 + mod_log_sql was benchmarked using the "ab" (Apache Bench) program that comes with the Apache distribution; here are the results. \layout Standard Overall configuration: \layout Itemize Machine A: Apache webserver \layout Itemize Machine B: MySQL server \layout Itemize Machines A and B connected with 100Mbps Ethernet \layout Itemize Webserver: Celeron 400, 128 MB RAM, IDE storage \layout Standard Apache configuration: \layout LyX-Code Timeout 300 \layout LyX-Code KeepAlive On \layout LyX-Code MaxKeepAliveRequests 100 \layout LyX-Code KeepAliveTimeout 15 \layout LyX-Code MinSpareServers 5 \layout LyX-Code StartServers 10 \layout LyX-Code MaxSpareServers 15 \layout LyX-Code MaxClients 256 \layout LyX-Code MaxRequestsPerChild 5000 \layout LyX-Code LogSQLTransferLogFormat AbHhmRSsTUuvc \layout LyX-Code LogSQLWhichCookie Clicks \layout LyX-Code CookieTracking on \layout LyX-Code CookieName Clicks \layout Standard "ab" commandline: \layout LyX-Code ./ab -c 10 -t 20 -v 2 -C Clicks=ab_run http://www.hostname.com/target \layout Standard ( 10 concurrent requests; 20 second test; setting a cookie "Clicks=ab_run"; target = the mod_log_sql homepage. ) \layout Standard Ten total ab runs were conducted: five with MySQL logging enabled, and five with all MySQL directives commented out of httpd.conf. Then each five were averaged. The results: \layout Itemize Average of five runs employing MySQL \emph on and \emph default standard text logging: \series bold 139.01 requests per second, zero errors \series default . \layout Itemize Average of five runs employing \emph on only \emph default standard text logging: \series bold 139.96 requests per second, zero errors \series default . \layout Standard In other words, any rate-limiting effects on this particular hardware setup are not caused by MySQL. Note that although this very simple webserver setup is hardly cutting-edge -- it is, after all, a fairly small machine -- 139 requests per second equal over \emph on twelve million hits per day. \layout Standard If you run this benchmark yourself, take note of three things: \layout Enumerate Use a target URL that is on your own webserver :-). \layout Enumerate Wait until all your connections are closed out between runs; after several thousand requests your TCP/IP stack will be filled with hundreds of connections in TIME_WAIT that need to close. Do a "netstat -t|wc -l" on the webserver to see. If you don't wait, you can expect to see a lot of messages like "ip_conntrack: table full, dropping packet" in your logs. (This has nothing to do with mod_log_sql, this is simply the nature of the TCP/IP stack in the Linux kernel.) \layout Enumerate When done with your runs, clean these many thousands of requests out of your database: \layout LyX-Code mysql> delete from access_log where agent like 'ApacheBench%'; \layout LyX-Code mysql> optimize table access_log; \layout Subsubsection Do I need to be worried about all the running MySQL children? Will holding open \emph on n \emph default Apache-to-MySQL connections consume a lot of memory? \layout Standard Short answer: you shouldn't be worried. \layout Standard Long answer: you might be evaluating at the output of \begin_inset Quotes eld \end_inset ps -aufxw \begin_inset Quotes erd \end_inset and becoming alarmed at all the 7MB httpd processes or 22MB mysqld children that you see. Don't be alarmed \emph on . \emph default It's true that mod_log_sql opens and holds open many MySQL connections: each httpd child maintains one open database connection (and holds it open for performance reasons). Four webservers, each running 20 Apache children, will hold open 80 MySQL connections, which means that your MySQL server needs to handle 80 simultaneous connections. In truth, your MySQL server needs to handle far more than that if traffic to your website spikes and the Apache webservers spawn off an additional 30 children each... \layout Standard Fortunately the cost reported by 'ps -aufxw' is deceptive. This is due to an OS memory-management feature called \begin_inset Quotes eld \end_inset copy-on-write. \begin_inset Quotes erd \end_inset When you have a number of identical child processes (e.g. Apache, MySQL), it would appear in \begin_inset Quotes eld \end_inset ps \begin_inset Quotes erd \end_inset as though each one occupies a great deal of RAM -- as much as 7MB per httpd child! In actuality each additional child only occupies a small bit of extra memory -- most of the memory pages are common to each child and therefore shared in a \begin_inset Quotes eld \end_inset read-only \begin_inset Quotes erd \end_inset fashion. The OS can get away with this because the majority of memory pages for one child are identical across all children. Instead of thinking of each child as a rubber stamp of the others, think of each child as a basket of links to a common memory area. \layout Standard A memory page is only duplicated when it needs to be written to, hence \begin_inset Quotes eld \end_inset copy-on-write. \begin_inset Quotes erd \end_inset The result is efficiency and decreased memory consumption. \begin_inset Quotes eld \end_inset ps \begin_inset Quotes erd \end_inset may report 7MB per child, but it might really only \begin_inset Quotes eld \end_inset cost \begin_inset Quotes erd \end_inset 900K of extra memory to add one more child. It is \series bold not \emph on \emph default correct \series default to assume that 20 Apache children with a VSZ of 7MB each equals \begin_inset Formula $(20\times7MB)$ \end_inset of memory consumption -- the real answer is much, much lower. The same \begin_inset Quotes eld \end_inset copy-on-write \begin_inset Quotes erd \end_inset rules apply to all your MySQL children: 40 mysqld children @ 22MB each \series bold do not \series default occupy 880MB of RAM. \layout Standard The bottom line: although there is a cost to spawn extra httpd or mysqld children, that cost is not as great as \begin_inset Quotes eld \end_inset ps \begin_inset Quotes erd \end_inset would lead you to believe. \layout Subsubsection My webserver cannot handle all the traffic that my site receives, is there anything I can do? \layout Standard If you have exhausted all the tuning possibilities on your existing server, it is probably time you evaluated the benefits of clustering two or more webservers together in a load-balanced fashion. In fact, users of such a setup are mod_log_sql's target audience! \layout Subsubsection \begin_inset LatexCommand \label{sub:DelayedInsFAQ} \end_inset What is the issue with activating delayed inserts? \layout Standard There are several. \layout Enumerate INSERT DELAYED is a specific syntax to MySQL and is not supported by any other database. Ergo, why is it needed, and what MySQL deficiency is it working around? INSERT DELAYED is a kluge. \layout Enumerate The MySQL documentation is unclear whether INSERT DELAYED is even necessary for an optimized database. It says, \begin_inset Quotes eld \end_inset The DELAYED option for the INSERT statement is a MySQL-specific option that is very useful if you have clients that can't wait for the INSERT to complete. \begin_inset Quotes erd \end_inset But then it goes on to say, \begin_inset Quotes eld \end_inset Note that as MyISAM tables supports concurrent SELECT and INSERT, if there is no free blocks in the middle of the data file, you very seldom need to use INSERT DELAYED with MyISAM. \begin_inset Quotes erd \end_inset \layout Enumerate Because INSERT DELAYED returns without waiting for the data to be written, a hard kill of your MySQL database at the right (wrong?) moment could lose those logfile entries. \layout Enumerate As of MySQL version 3.23.52, the error return functions disagree after a failed INSERT DELAYED: mysql_errno() always returns 0, even if mysql_error() returns a textual error. I have reported this bug to the MySQL folks. However, we have no way of knowing what solution they will adopt to fix this, and with the worst case solution mod_log_sql would not be able to tell if anything went wrong with a delayed insert. \layout Standard Instead of delayed inserts, you may wish to utilize InnoDB tables (instead of the standard MyISAM tables). InnoDB tables suppot row-level locking and are recommended for high-volume databases. \layout Standard If after understanding these problems you still wish to enable delayed inserts, section \begin_inset LatexCommand \ref{sub:DelayedIns} \end_inset discusses how. \layout Subsection \begin_inset Quotes eld \end_inset How do I...? \begin_inset Quotes erd \end_inset -- accomplishing certain tasks \layout Subsubsection How do I extract the data in a format that my analysis tool can understand? \layout Standard mod_log_sql would be virtually useless if there weren't a way for you to extract the data from your database in a somewhat meaningful fashion. To that end there's a Perl script enclosed with the distribution. That script (make_combined_log.pl) is designed to extract N-many days worth of access logs and provide them in a Combined Log Format output. You can use this very tool right in /etc/crontab to extract logs on a regular basis so that your favorite web analysis tool can read them. Or you can examine the Perl code to construct your own custom tool. \layout Standard For example, let's say that you want your web statistics updated once per day in the wee hours of the morning. A good way to accomplish that could be the following entries in /etc/crontab: \layout LyX-Code # Generate the temporary apache logs from the MySQL database (for webalizer) \layout LyX-Code 05 04 * * * root make_combined_log.pl 1 www.grubbybaby.com > /var/log/temp01 \layout LyX-Code # Run webalizer on httpd log \layout LyX-Code 30 04 * * * root webalizer -c /etc/webalizer.conf; rm -f /var/log/temp01 \layout Standard Or if you have a newer system that puts files in /etc/cron.daily etc., create a file called \begin_inset Quotes eld \end_inset webalizer \begin_inset Quotes srd \end_inset in the cron.daily subdirectory. Use the following as the contents of your file, and make sure to chmod 755 it when done. \layout LyX-Code #!/bin/sh \layout LyX-Code /usr/local/sbin/make_combined_log.pl 1 www.yourdomain.com > /var/log/httpd/templog \layout LyX-Code /usr/local/bin/webalizer -q -c /etc/webalizer.conf \layout LyX-Code rm -f /var/log/httpd/templog \layout Standard See? Easy. \layout Subsubsection \begin_inset LatexCommand \label{sec:cookie} \end_inset How can I log mod_usertrack cookies? \layout Standard A number of people like to log mod_usertrack cookies in their Apache TransferLog to aid in understanding their visitors' clickstreams. This is accomplished, for example, with a statement as follows: \layout LyX-Code LogFormat "%h %l %u %t \backslash "%r \backslash " %s %b \backslash "%{Referer}i \backslash " \backslash "%{User-Agent}i \backslash "" \backslash "%{cookie}n \backslash "" \layout Standard Naturally it would be nice for mod_log_sql to permit the admin to log the cookie data as well, so as of version 1.10 you can do this. You need to have already compiled mod_usertrack into httpd -- it's one of the standard Apache modules. \layout Standard First make sure you have a column called "cookie" in the MySQL database to hold the cookies, which can be done as follows if you already have a working database: \layout LyX-Code alter table acc_log_tbl add column cookie varchar(255); \layout Standard Next configure your server to set usertracking cookies as follows, and make sure you include the new 'c' directive in your \noun on LogSQLTransferLogFormat \noun default , which activates cookie logging. Here's an example: \layout LyX-Code \layout LyX-Code CookieTracking on \layout LyX-Code CookieStyle Cookie \layout LyX-Code CookieName Foobar \layout LyX-Code LogSQLTransferLogFormat huSUsbTvRAc \layout LyX-Code LogSQLWhichCookie Foobar \layout LyX-Code \layout Standard The first three lines configure mod_usertrack to create a COOKIE (RFC 2109) format cookie called Foobar. The last two lines tell mod_log_sql to log cookies named Foobar. You have to choose which cookie to log because more than one cookie can/will be sent to the server by the client. \layout Standard Recap: the 'c' character \emph on activates \emph default cookie logging, and the \noun on LogSQLWhichCookie \noun default directive \emph on chooses \emph default which cookie to log. \layout Standard FYI, you are advised NOT to use \noun on CookieStyle Cookie2 \noun default -- it seems that even newer browsers (IE 5.5, etc.) have trouble with the new COOKIE2 (RFC 2965) format. Just stick with the standard COOKIE format and you'll be fine. \layout Standard Perform some hits on your server and run a select: \layout LyX-Code mysql> select request_uri,cookie from access_log where cookie is not null; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard cookie \end_inset \begin_inset Text \layout Standard /mod_log_sql/ \end_inset \begin_inset Text \layout Standard ool-18e4.dyn.optonline.net.130051007102700823 \end_inset \begin_inset Text \layout Standard /mod_log_sql/usa.gif \end_inset \begin_inset Text \layout Standard ool-18e4.dyn.optonline.net.130051007102700823 \end_inset \begin_inset Text \layout Standard /mod_log_sql/style_1.css \end_inset \begin_inset Text \layout Standard ool-18e4.dyn.optonline.net.130051007102700823 \end_inset \end_inset \layout LyX-Code \layout Subsubsection What if I want to log more than one cookie? What is the difference between LogSQLWhichCookie and LogSQLWhichCookies? \layout Standard As of version 1.17, you have a choice in how you want cookie logging handled. \layout Standard If you are interested in logging only one cookie per request, follow the instructions in section \begin_inset LatexCommand \ref{sec:cookie} \end_inset above. That cookie will be logged to a column in the regular access_log table, and the actual cookie you want to log is specified with \noun on LogSQLWhichCookie \noun default . Don't forget to specify the 'c' character in \noun on LogSQLTransferLogFormat \noun default . \layout Standard If, however, you need to log multiple cookies per request, you must employ the \noun on LogSQLWhichCookies \noun default (note the plural) directive. The cookies you specify will be logged to a separate table (as discussed in section \begin_inset LatexCommand \ref{secMulTable} \end_inset ), and entries in that table will be linked to the regular access_log entries via the unique ID that is supplied by mod_unique_id. Without mod_unique_id the information will still be logged but you will be unable to correlate which cookies go with which access-requests. Furthermore, with \noun on LogSQLWhichCookies \noun default , you do \series bold not \series default need to include the 'c' character in \noun on LogSQLTransferLogFormat \noun default . \layout Standard \noun on LogSQLWhichCookie \noun default and \noun on LogSQLWhichCookies \noun default can coexist without conflict because they operate on entireley different tables, but you're better off choosing the one you need. \layout Subsubsection What are the SSL logging features, and how do I activate them? \layout Standard Note: you do \series bold not \series default need to compile SSL support into mod_log_sql in order to simply use it with a secure site. You only need to compile SSL support into mod_log_sql if you want to log SSL-specific data such as the cipher type used, or the keysize that was negotiated. If that information is unimportant to you, you can ignore this FAQ. \layout Standard By adding certain characters to your \noun on LogSQLTransferLogFormat \noun default string you can tell mod_log_sql to log the SSL cipher, the SSL keysize of the connection, and the maximum keysize that was available. This would let you tell, for example, which clients were using only export-grad e security to access your secure software area. \layout Standard You can compile mod_log_sql with SSL logging support if you have the right packages installed. If you already have an SSL-enabled Apache then you by definition have the correct packages already installed: OpenSSL and mod_ssl. \layout Standard You need to ensure that your database is set up to log the SSL data. Issue the following commands to MySQL if your access table does not already have them: \layout LyX-Code alter table access_log add column ssl_cipher varchar(25); \layout LyX-Code alter table access_log add column ssl_keysize smallint unsigned; \layout LyX-Code alter table access_log add column ssl_maxkeysize smallint unsigned; \layout Standard Finally configure httpd.conf to activate the SSL fields. Note that this is only meaningful in a VirtualHost that is set up for SSL. \layout LyX-Code \layout LyX-Code LogSQLTransferLogFormat AbHhmRSsTUuvc \series bold Qqz \series default \layout LyX-Code \layout Standard The last three characters (Qqz) in the directive are the SSL ones; see section \begin_inset LatexCommand \ref{sub:Frmat} \end_inset in the directives documentation for details of the \noun on LogSQLTransferLogFormat \noun default directive. \layout Standard Restart Apache, then perform some hits on your server. Then run the following select statement: \layout LyX-Code mysql> select remote_host,request_uri,ssl_cipher,ssl_keysize,ssl_maxkeysize \layout LyX-Code from access_log where ssl_cipher is not null; \layout LyX-Code \layout Standard \align center \begin_inset Tabular \begin_inset Text \layout Standard remote_host \end_inset \begin_inset Text \layout Standard request_uri \end_inset \begin_inset Text \layout Standard ssl_cipher \end_inset \begin_inset Text \layout Standard ssl_keysize \end_inset \begin_inset Text \layout Standard ssl_maxkeysize \end_inset \begin_inset Text \layout Standard 216.190.52.4 \end_inset \begin_inset Text \layout Standard /dir/somefile.html \end_inset \begin_inset Text \layout Standard RC4-MD5 \end_inset \begin_inset Text \layout Standard 128 \end_inset \begin_inset Text \layout Standard 128 \end_inset \begin_inset Text \layout Standard 216.190.52.4 \end_inset \begin_inset Text \layout Standard /dir/somefile.gif \end_inset \begin_inset Text \layout Standard RC4-MD5 \end_inset \begin_inset Text \layout Standard 128 \end_inset \begin_inset Text \layout Standard 128 \end_inset \begin_inset Text \layout Standard 216.190.52.4 \end_inset \begin_inset Text \layout Standard /dir/somefile.jpg \end_inset \begin_inset Text \layout Standard RC4-MD5 \end_inset \begin_inset Text \layout Standard 128 \end_inset \begin_inset Text \layout Standard 128 \end_inset \end_inset \layout LyX-Code \the_end