Well, the one index:
CREATE INDEX acceptedbilling_to_date
_accepted_billing_dt_idx
ON acceptedbilling
USING btree
(to_date(accepted_billing_dt::text, 'yyyymmdd'::text));.
Reject:
ERROR: functions in index expression must be marked IMMUTABLE
SQL state: 42P17
Is actually a date stored in a varchar field (stupid I know, but it's a continual fight between the me (the dba), management, and our COBOL programmers). I was indexing it as a date so that I can treat it as a date in some of the non-COBOL programs/utilities that we have written.
The second index is rather stupid, it was an early index before I figured out how to split a timestamp.
Anyway, is there a way to make the first index work? Otherwise we end up with a seq scan on our billing table which is very painful.
Thanks,
Chris
On 6/6/07, Tom Lane <tgl@sss.pgh.pa.us> wrote: Alvaro Herrera <alvherre@commandprompt.com> writes:
> You can't do this because to_date and other functions are not immutable.
> 8.2 seems to be more picky about this -- the date conversions of
> timestamptz columns are dependent on the current timezone.
The reason 8.2 is more picky is that the function is less immutable
thanks to the addition of locale-dependent functionality:
http://archives.postgresql.org/pgsql-committers/2006-11/msg00264.php
I gather that the underlying column is timestamp without tz, or it would
never have worked in 8.1 either. That being the case, these index
definitions seem pretty darn stupid anyway --- why aren't you just
indexing on date_trunc or a plain cast to date?
regards, tom lane