For example, if you use Apache::DBI, modify your httpd.conf file with:

PerlSetEnv DBI_TRACE "3=~/tmp/dbitrace.log"
PerlModule Apache::DBI

Replace 3 with the trace level you want. The traces from each request will be appended to /tmp/dbitrace.log. Note that the logs will probably be interleaved if requests are processed concurrently.

Within your code, you can control trace generation with the trace( ) method:

DBI->trace($trace_level)
DBI->trace($trace_level, $trace_filename)

DBI trace information can be enabled for all handles using this DBI class method. To enable trace information for a specific handle, use the similar $dbh->trace method.

Using the trace option with a $dbh or $sth handle is useful to limit the trace information to the specific bit of code that you are debugging.

The trace levels are:

0

Trace disabled

1

Trace DBI method calls returning with results

2

Trace method entry with parameters and exit with results

3

As above, adding some high-level information from the driver and also adding some internal information from the DBI

4

As above, adding more detailed information from the driver and also including DBI mutex information when using threaded Perl

5+

As above, but with more and more obscure information

20.2. Improving Performance		20.4. References