Prevent Postgresql from logging unique key errors without affecting other error logging

Question

Is there a way to prevent Postgresql from logging ERRORs caused by attempted insertions where a UNIQUE KEY constraint is violated?

I could change the server_log_min directive, but this would disable all ERROR messages and not just those for UNIQUE KEY constraint.

Answer 1

No. No such way exists. Short of piping logs via | grep -v ... | filter.

Answer 2

There's no way to do this just by adjusting the logging mechanism on the server. You could do it by hacking the source code if you absolutely had to; the relevant code is in src/backend/access/nbtree/nbtinsert.c and looks like this, around line 300:

ereport(ERROR,
    (errcode(ERRCODE_UNIQUE_VIOLATION),
        errmsg("duplicate key value violates unique constraint \"%s\"",
            RelationGetRelationName(rel))));

You could change the log level there from ERROR to LOG or NOTICE.