From: Tom Lane <tgl@sss.pgh.pa.us>
To: Wells Oliver <wells.oliver@gmail.com>
Cc: pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: Creating an index on a timestamp with time zone cast to a date-- possible?
Date: Mon, 24 May 2021 14:24:47 -0400
Message-ID: <1012707.1621880687@sss.pgh.pa.us> (raw)
In-Reply-To: <CAOC+FBX+0=rvSsVRA8=PZAc9ccDq--c5OUiQ0WNxGzGgxh_-eA@mail.gmail.com>
References: <CAOC+FBX+0=rvSsVRA8=PZAc9ccDq--c5OUiQ0WNxGzGgxh_-eA@mail.gmail.com>
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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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, wells.oliver@gmail.com
Subject: Re: Creating an index on a timestamp with time zone cast to a date-- possible?
In-Reply-To: <1012707.1621880687@sss.pgh.pa.us>
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