This week's giveaway is in the Java/Jakarta EE forum. We're giving away four copies of Java EE 8 High Performance and have Romain Manni-Bucau on-line! See It is also noteworthy that although the failure firstly occurred this Friday before noon, there was a holiday in our country and the DB load was smaller than usual for normal working day.
The cause was not yet pinned down. We've been asked to review our application for possible causes. As far as I know, the most common reason for this error is not using bind variables (we do use binds; in some queries binds are not used to help optimize them, but these are run only a handful times each hour) and some very large packages (we do have a few packages, but nowhere near large; the largest has a few tens of KB).
We have one DB link to another Oracle instance. Our application runs periodically a few queries to scan for changes (including queries using the DB link), but these touch only around five tables. We have some 300 triggers (three - insert, update, delete - on each of about 100 tables), but these triggers call stored procedures in a package and only a handful of these tables are actually active. Furthermore, these things have been unchanged for months.