From: | "Tang, Haiying" <tanghy(dot)fnst(at)cn(dot)fujitsu(dot)com> |
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To: | Greg Nancarrow <gregn4422(at)gmail(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Antonin Houska <ah(at)cybertec(dot)at>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, "Bharath Rupireddy" <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)fujitsu(dot)com>, "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> |
Subject: | RE: Parallel INSERT (INTO ... SELECT ...) |
Date: | 2021-02-01 08:19:56 |
Message-ID: | d45961bef6304fd69afd2669d5dc100c@G08CNEXMBPEKD05.g08.fujitsu.local |
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Lists: | pgsql-hackers |
Hi Greg,
Recently, I was keeping evaluating performance of this patch(1/28 V13).
Here I find a regression test case which is parallel insert with bitmap heap scan.
when the target table has primary key or index, then the patched performance will have a 7%-19% declines than unpatched.
Could you please have a look about this?
I tried max_parallel_workers_per_gather=2/4/8, and I didn't tune other parameters(like GUCs or other enforce parallel parameters).
1. max_parallel_workers_per_gather=2(default)
target_table patched master %reg
------------------------------------------------------
without_PK_index 83.683 142.183 -41%
with_PK 382.824 321.101 19%
with_index 372.682 324.246 15%
2. max_parallel_workers_per_gather=4
target_table patched master %reg
------------------------------------------------------
without_PK_index 73.189 141.879 -48%
with_PK 362.104 329.759 10%
with_index 372.237 333.718 12%
3. max_parallel_workers_per_gather=8 (also set max_parallel_workers=16, max_worker_processes = 16)
target_table patched master %reg
------------------------------------------------------
without_PK_index 75.072 146.100 -49%
with_PK 365.312 324.339 13%
with_index 362.636 338.366 7%
Attached test_bitmap.sql which includes my test data and sql if you want to have a look.
Regards,
Tang
Attachment | Content-Type | Size |
---|---|---|
test_bitmap.sql | application/octet-stream | 1.1 KB |
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