On 02/28/2017 01:35 AM, Sven R. Kunze wrote:
On 27.02.2017 18:17, Adrian Klaver wrote:
Yes, but is not about timezone dependency, it is about the other
dependencies listed in the second and third points. Namely the
datestyle setting and magic strings e.g. 'now'
I am sorry, I still don't understand. to_date and to_timestamp require
datestyle settings per se and magic strings don't work.
See here:
https://www.postgresql.org/message-id/11190.1488127834%40sss.pgh.pa.us
"There are multiple reasons why the text-to-datetime conversion
functions are not immutable"
Tom was referring to the text --> date cast you where attempting in your
original index definition:
create index docs_birthdate_idx ON docs using btree
(((meta->>'birthdate')::date));
So:
test=> select 'today'::date;
date
------------
2017-02-28
(1 row)
test=> select 'now'::date;
date
------------
2017-02-28
(1 row)
test=> set datestyle = 'SQL, DMY';
SET
test=> select 'today'::date;
date
------------
28/02/2017
(1 row)
test=> select 'now'::date;
date
------------
28/02/2017
(1 row)
Now you tried to work around the casting issue by using to_timestamp:
create index docs_birthdate_idx ON docs using btree
((to_timestamp(meta->>'birthdate', 'YYYY-MM-DD') at time zone 'UTC'));
but that introduced the issue that to_timestamp returns a timestamptz
and so you end up with a dependency on timezones.
=# -- required datestyle
=# select to_date('2000-01-01');
ERROR: function to_date(unknown) does not exist
LINE 1: select to_date('2000-01-01');
^
HINT: No function matches the given name and argument types. You might
need to add explicit type casts.
=# -- magic strings don't work
=# select to_date('');
ERROR: invalid value "epoc" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('epoch', 'YYYY-MM-DD');
ERROR: invalid value "epoc" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('infinity', 'YYYY-MM-DD');
ERROR: invalid value "infi" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('-infinity', 'YYYY-MM-DD');
ERROR: invalid value "-inf" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('now', 'YYYY-MM-DD');
ERROR: invalid value "now" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('today', 'YYYY-MM-DD');
ERROR: invalid value "toda" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('tomorrow', 'YYYY-MM-DD');
ERROR: invalid value "tomo" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('yesterday', 'YYYY-MM-DD');
ERROR: invalid value "yest" for "YYYY"
DETAIL: Value must be an integer.
=# select to_date('allballs', 'YYYY-MM-DD');
ERROR: invalid value "allb" for "YYYY"
DETAIL: Value must be an integer.
Regards,
Sven
--
Adrian Klaver
adrian.kla...@aklaver.com
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