Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables

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От Alvaro Herrera
Тема Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables
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Msg-id 20170919102005.pn7rtotdymlitpyt@alvherre.pgsql
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Ответ на Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables  (Rafia Sabih <rafia.sabih@enterprisedb.com>)
Ответы Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables  (Rafia Sabih <rafia.sabih@enterprisedb.com>)
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Rafia Sabih wrote:

> On completing the benchmark for all queries for the above mentioned
> setup, following performance improvement can be seen,
> Query | Patch | Head
> 3  | 1455  |  1631
> 4  |  499  |  4344
> 5  |  1464  |  1606
> 10  |  1475  |  1599
> 12  |  1465  |  1790
> 
> Note that all values of execution time are in seconds.
> To summarise, apart from Q4, all other queries are showing somewhat
> 10-20% improvement.

Saving 90% of time on the slowest query looks like a worthy improvement
on its own right.  However, you're reporting execution time only, right?
What happens to planning time?  In a quick look,

$ grep 'Planning time' pg_part_*/4*
pg_part_head/4_1.out: Planning time: 3390.699 ms
pg_part_head/4_2.out: Planning time: 194.211 ms
pg_part_head/4_3.out: Planning time: 210.964 ms
pg_part_head/4_4.out: Planning time: 4150.647 ms
pg_part_patch/4_1.out: Planning time: 7577.247 ms
pg_part_patch/4_2.out: Planning time: 312.421 ms
pg_part_patch/4_3.out: Planning time: 304.697 ms
pg_part_patch/4_4.out: Planning time: 269.778 ms

I think the noise in these few results is too large to draw any
conclusions.  Maybe a few dozen runs of EXPLAIN (w/o ANALYZE) would tell
something significant?

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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