Quoting from the docs:
DBI::ProfileDumper::Apache - capture DBI profiling data from Apache/mod_perl
Add this line to your httpd.conf:
PerlSetEnv DBI_PROFILE DBI::ProfileDumper::Apache
Then restart your server. Access the code you wish to test using a web browser, then shutdown your server. This will create a set of dbi.prof.* files in your Apache log
directory. Get a profiling report with dbiprof:
When you're ready to perform another profiling run, delete the old files
and start again.
Additionally, if you wish to fine tune your profiling needs, see Speeding up the DBI for some examples on how to include profiling code (using DBI::Profile) in your application.