From: | Qingqing Zhou <zhouqq(dot)postgres(at)gmail(dot)com> |
---|---|
To: | Ram N <yramiyer(at)gmail(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Performance issue with NestedLoop query |
Date: | 2015-08-05 17:12:46 |
Message-ID: | CAJjS0u30tchMJdEgExZBqeJkdXXtgBwbn5Uvi17zWwNkvjF7TA@mail.gmail.com |
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Thread: | |
Lists: | pgsql-performance |
On Tue, Aug 4, 2015 at 8:40 PM, Ram N <yramiyer(at)gmail(dot)com> wrote:
>
> Thanks much for responding guys. I have tried both, building multi column
> indexes and GIST, with no improvement. I have reduced the window from 180
> days to 30 days and below are the numbers
>
> Composite index - takes 30 secs
>
> With Btree indexing - takes 9 secs
>
> With GIST - takes >30 secs with kind of materialize plan in explain
>
> Any other ideas I can do for window based joins.
>
From this query:
select sum(a), count(id), a.ts, st from table1 a, table2 b where a.ts
> b.start_date and a.ts < b.end_date and a.ts > '2015-01-01
20:50:44.000000 +00:00:00' and a.ts < '2015-07-01 19:50:44.000000
+00:00:00' group by a.ts, st order by a.ts
We can actually derive that b.start_date > '2015-07-01 19:50:44.000000
+00:00:00' and b.end_date < '2015-01-01 20:50:44.000000 +00:00:00'. If
we add these two predicates to the original query, does it help?
Thanks,
Qingqing
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