Re: [HACKERS] Block level parallel vacuum

From: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, Mahendra Singh Thalor <mahi6run(at)gmail(dot)com>, Amit Langote <langote_amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Claudio Freire <klaussfreire(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Sergei Kornilov <sk(at)zsrv(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Subject: Re: [HACKERS] Block level parallel vacuum
Date: 2020-01-17 07:20:46
Message-ID: CAFiTN-txNC3fY3dMae=wREgVbk6ZEmepJsjRek7K3JbX2No=8g@mail.gmail.com
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On Fri, Jan 17, 2020 at 11:39 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
I have performed cost delay testing on the latest test(I have used
same script as attahced in [1] and [2].
vacuum_cost_delay = 10
vacuum_cost_limit = 2000

Observation: As we have concluded earlier, the delay time is in sync
with the I/O performed by the worker
and the total delay (heap + index) is almost the same as the
non-parallel operation.

test1:[1]

Vacuum non-parallel

WARNING: VacuumCostTotalDelay=11332.320000

Vacuum 2 workers
WARNING: worker 0 delay=171.085000 total io=34288 hit=22208 miss=0 dirty=604
WARNING: worker 1 delay=87.790000 total io=17910 hit=17890 miss=0 dirty=1
WARNING: worker 2 delay=88.620000 total io=17910 hit=17890 miss=0 dirty=1

WARNING: VacuumCostTotalDelay=11505.650000

Vacuum 4 workers
WARNING: worker 0 delay=87.750000 total io=17910 hit=17890 miss=0 dirty=1
WARNING: worker 1 delay=89.155000 total io=17910 hit=17890 miss=0 dirty=1
WARNING: worker 2 delay=87.080000 total io=17910 hit=17890 miss=0 dirty=1
WARNING: worker 3 delay=78.745000 total io=16378 hit=4318 miss=0 dirty=603

WARNING: VacuumCostTotalDelay=11590.680000

test2:[2]

Vacuum non-parallel
WARNING: VacuumCostTotalDelay=22835.970000

Vacuum 2 workers
WARNING: worker 0 delay=345.550000 total io=69338 hit=45338 miss=0 dirty=1200
WARNING: worker 1 delay=177.150000 total io=35807 hit=35787 miss=0 dirty=1
WARNING: worker 2 delay=178.105000 total io=35807 hit=35787 miss=0 dirty=1
WARNING: VacuumCostTotalDelay=23191.405000

Vacuum 4 workers
WARNING: worker 0 delay=177.265000 total io=35807 hit=35787 miss=0 dirty=1
WARNING: worker 1 delay=177.175000 total io=35807 hit=35787 miss=0 dirty=1
WARNING: worker 2 delay=177.385000 total io=35807 hit=35787 miss=0 dirty=1
WARNING: worker 3 delay=166.515000 total io=33531 hit=9551 miss=0 dirty=1199
WARNING: VacuumCostTotalDelay=23357.115000

[1] https://www.postgresql.org/message-id/CAFiTN-tFLN%3Dvdu5Ra-23E9_7Z1JXkk5MkRY3Bkj2zAoWK7fULA%40mail.gmail.com
[2] https://www.postgresql.org/message-id/CAFiTN-tC%3DNcvcEd%2B5J62fR8-D8x7EHuVi2xhS-0DMf1bnJs4hw%40mail.gmail.com

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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