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* Creating an index on a timestamp with time zone cast to a date-- possible?
@ 2021-05-24 18:19 Wells Oliver <wells.oliver@gmail.com>
0 siblings, 1 reply; 2+ messages in thread
From: Wells Oliver @ 2021-05-24 18:19 UTC (permalink / raw)
To: pgsql-admin
Seems you can't do this:
create index on someschema.sometable ((modified_at::date));
If modified_at is a timestamp with a time zone:
ERROR: functions in index expression must be marked IMMUTABLE
But you can if it's a timestamp without a time zone. Anyway, any way of
casting that as to use it as an index?
--
Wells Oliver
wells.oliver@gmail.com <wellsoliver@gmail.com>
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Creating an index on a timestamp with time zone cast to a date-- possible?
@ 2021-05-24 18:24 Tom Lane <tgl@sss.pgh.pa.us>
parent: Wells Oliver <wells.oliver@gmail.com>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2021-05-24 18:24 UTC (permalink / raw)
To: Wells Oliver <wells.oliver@gmail.com>; +Cc: pgsql-admin
Wells Oliver <wells.oliver@gmail.com> writes:
> Seems you can't do this:
> create index on someschema.sometable ((modified_at::date));
> If modified_at is a timestamp with a time zone:
> ERROR: functions in index expression must be marked IMMUTABLE
> But you can if it's a timestamp without a time zone. Anyway, any way of
> casting that as to use it as an index?
The problem is that casting a timestamptz to a date (or a timestamp
for that matter) depends on your current timezone setting.
You could do something like
create index on sometable (((modified_at at time zone 'UTC')::date));
regards, tom lane
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2021-05-24 18:19 Creating an index on a timestamp with time zone cast to a date-- possible? Wells Oliver <wells.oliver@gmail.com>
2021-05-24 18:24 ` Tom Lane <tgl@sss.pgh.pa.us>
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