Re: Range contains element filter not using index of the element column

On 11/27/19 6:33 AM, Lauri Kajan wrote:
> On Wed, Nov 27, 2019 at 1:05 PM Игорь Выскорко <vyskorko(dot)igor(at)yandex(dot)ru
> <mailto:vyskorko(dot)igor(at)yandex(dot)ru>> wrote:
>
> Hi!
> Do you use GIST index?
> According to
> https://www.postgresql.org/docs/12/rangetypes.html#RANGETYPES-INDEXING
> <@ operator is supported:
> > A GiST or SP-GiST index can accelerate queries involving these
> range operators: =, &&, <@, @>, <<, >>, -|-, &<, and &>
>
>
> Hi,
>
> I have understood that gist indexes can be used if the column is range
> type but my column is just plain timestamp.
> I tried actually to add gist index for the timestamp column. That was
> not possible without installing the btree_gist extension. But that
> didn't work.

Try this:

create table tstest(id int, ts timestamptz);
insert into tstest
select
g.i,
now() - (g.i::text || ' days')::interval
from generate_series(1, 100000) as g(i);

create index tstest_gin
on tstest using gist((tstzrange(ts,ts,'[]')));

explain analyze
select * from tstest
where
tstzrange(ts,ts,'[]') <@
tstzrange(now()- '9 days'::interval,
now()-'7 days'::interval,'(]');
QUERY PLAN

--------------------------------------------------------
Bitmap Heap Scan on tstest (cost=24.17..590.16 rows=500 width=12)
(actual time=0.069..0.070 rows=2 loops=1)
Recheck Cond: (tstzrange(ts, ts, '[]'::text) <@ tstzrange((now() - '9
days'::interval), (now() - '7 days'::interval), '(]'::text))
Heap Blocks: exact=1
-> Bitmap Index Scan on tstest_gin (cost=0.00..24.04 rows=500
width=0) (actual time=0.063..0.063 rows=2 loops=1)
Index Cond: (tstzrange(ts, ts, '[]'::text) <@ tstzrange((now()
- '9 days'::interval), (now() - '7 days'::interval), '(]'::text))
Planning Time: 20.920 ms
Execution Time: 0.115 ms
(7 rows)

HTH,

Joe

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