Re: PL/pgSQL trigger and sequence increment

> Seems like you would be a lot better off enforcing this with a unique
> index on (submitter_id, date_trunc('month',entry_timestamp)).  The above
> not only doesn't provide any feedback, it's got serious race-condition
> problems.

Unfortunately, it didn't work.

CREATE UNIQUE INDEX one_entry_per_submitter_per_month ON table_entry
(submitter_id , date_trunc('month',entry_timestamp));

runs into

ERROR:  functions in index expression must be marked IMMUTABLE.

If I'm reading this correctly, date_trunc is not IMMUTABLE and thus
not usable in an index.


Dominic Jones, Ph.D.