ORA-08177: can't serialize access for this transaction

[Rod Widdowson]

> Quite new to Shibboleth and I can't say I completely understand the explanation in thread --- is it due to a race
> condition, what steps can alleviate it?

The SQL standard defines rules for how locking around transactions should work.  In their race to prove how fast they are many vendors completely ignore these rules ("performance enhancement through incorrect operation").

In order to deal with their shoddy coding, applications have to take remedial action and "if it fails, try again" ("Oh look, that million dollar transfer I made probably didn't work, maybe I should try again").

Shibboleth has code to allow you to do this, but you have to enable it. - if you look here [1] you will see examples:

> The most common settings to override are the queryTimeout, and to provide a list of retryableErrors that 
> are reported when a database improperly fails to prevent a duplicate insert.

[1] https://wiki.shibboleth.net/confluence/display/IDP30/PersistentNameIDGenerationConfiguration