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$Id: README,v 1.5 2002/04/21 23:01:53 helios Exp $


Homepage
--------
http://www.grubbybaby.com/mod_log_mysql/



Approach
--------

In order to save speed and overhead, links are kept alive in between
queries.  This module uses one SQL link per httpd process.  Among other
things, this means that this module supports logging into only one
MySQL server, and for now, also, only one SQL database.

Virtual hosts are supported in the same manner they are in the regular
logging modules.  If you specify a different table for a virtual
host it will be used, otherwise the 'general' would be used.

SQL links are opened by each child process when it is born.  Error reporting
is robust throughout and will let you know about database issues
in the standard Apache error-log for the server or virtual server. 

A robust "preserve" capability has now been implemented as well.  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, you reboot the machine, etc. -- mod_log_mysql
will note this in the error log and begin appending its log entries to
the preserve file.  At the time that your MySQL server returns to service,
each of these preserve files is easily imported because it is stored in SQL:

  # mysql -uadminuser -p mydbname < /tmp/mysql-preserve



Supported directives
--------------------

Please see the web-based documentation for full explanation of all
supported run-time directives.

 http://www.grubbybaby.com/mod_log_mysql/directives.html

See the FAQ for some handy examples:

 http://www.grubbybaby.com/mod_log_mysql/faq.html


What gets logged by default?
----------------------------

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.

The online documentation of the run-time directives includes a full
explanation of what you can log, including examples.
  
  
Notes
-----

* You will customarily set most of your run-time configuration directives
  on a per-virtualserver basis, with only MySQLMassVirtualHosting,
  MySQLLoginInfo and MySQLDatabase 'outside' in the main server config.
  Any directives other than those in the main config do NOT get inherited
  by the virutal servers.

* The 'time_stamp' field is stored in an UNSIGNED INTEGER column, in the
  standard unix "seconds since 1/1/1970 12:00:00" format.  This is
  superior to storing the access time as a string due to size
  requirements: an UNSIGNED INT type fits in 4 bytes, whereas the Apache date
  string (e.g. "18/Nov/2001:13:59:52 -0800") requires 26 bytes --
  significantly larger, and those extra 22 bytes will add up over the
  thousands of accesses that a busy server will experience.  Besides,
  an INT type is far more flexible for comparisons, etc.

  In MySQL 3.21 and above you can easily convert this to a human
  readable format using from_unixtime(), e.g.:

  select remote_host,request_uri,from_unixtime(time_stamp) from access_log;

  The enclosed perl program make_combined_log.pl shows how you can
  extract your access records in a format that is completely Combined
  Log Format compliant.  You can then feed this to your favorite web
  log analysis tool.

* 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-length and will be padded with spaces.  Just like the
  time_stamp described above, that kind of space waste will add up over
  thousands of records.

* 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 or the INSERT
  will fail.  

* Apache normally logs numeric fields with a '-' character to mean "not
  applicable," e.g. bytes_sent on a request with a 304 response code. 
  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.



Author / Maintainer
-------------------

The actual logging code was taken from the already existing flat file
text modules, so all that credit goes to the Apache Server group.  

The MySQL routines and directives were added by Zeev Suraski
<bourbon@netvision.net.il>.

All changes from 1.06+ and the new documentation were added by 
Chris Powell <chris@grubbybaby.com>.  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.