Error explaination?

Folks,

I have a fuction that creates a record in a table called user_locks,
does a bunch of stuff, then deletes the record. However, when I try to
run it, I get the following error:

ERROR: triggered data change violation on relation "user_locks"

It appears that the function handler won't let me create, then delete
the same record. What goes on?

-Josh Berkus

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