About this blog

As with my website, my blogs espouse the philosophy “not all performance problems are technical” and that in most stable environments user behaviour / usage patterns are typically the source of most correctable performance problems. So if you are into bits, bytes, locks, latches etc this is not the place for you, but if you are after ways to genuinely enhance performance and work with your systems and customers to achieve better, more predictable performance, read on.

Saturday, November 6, 2010

Case Review - How did I manage to get 30 million rows in my fnd_logins table?

The site in presented with over 30 million rows in the fnd_logins table, growing at a rate of approximately 25,000 records per day.

Based on the site’s application activity, the estimated number of rows that should be held in the fnd_logins table should be around 800,000 records (i.e. holding 32 days history on-line). It is expected that this number should reduce post concurrent manager activity review.

The site was running the concurrent program Purge Signon Audit data (FNDSCPRG) daily as part of their normal maintenance program to purge the sign-on audit data and was unaware of the high growth rate in the sign-on audit tables.

On review of the site’s scheduled requests it was found that the Purge Signon Audit data was being run daily with the date argument set to 10-Oct-06, however, “the increment date parameter each run” check box had not been checked when the scheduled request was created. As such the data parameter has not been incrementing with each run, thus with each run the program has been purging all sign-on audit records prior to 10-Oct-06. As a result any record added after that date has not been being purged.

So, since 10-Oct-06 (Over 1,200 days at the time of presentation) the program has been running but purging nothing.

Whilst there are several inherent performance issues, the biggest impact to the application would be when the concurrent program runs. The concurrent program Purge Signon Audit data (FNDSCPRG) uses an un-indexed column start_time in its execution. As such the purge program will execute a full scan on each of the target tables in order to determine the rows to delete. So for this site, that would include a daily full scan of a 30 million to not find any rows to delete.

The case review shows how I would “Fix” the issue including deleting the unwanted rows and setting up a new Purge Signon Audit data scheduled program run.

The full case review can be found at -
http://www.piper-rx.com/pages/case_reviews/case_sign_on_audit.pdf

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