Re: Patch: Write Amplification Reduction Method (WARM)

From: Jaime Casanova <jaime(dot)casanova(at)2ndquadrant(dot)com>
To: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>
Cc: Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch: Write Amplification Reduction Method (WARM)
Date: 2016-12-26 06:19:33
Message-ID: CAJGNTeNYhDS2SoE4xEDcSyNACEE+eJWt6zOATW8Zm-NH+S1LLA@mail.gmail.com
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On 2 December 2016 at 07:36, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> wrote:
>
> I've updated the patches after fixing the issue. Multiple rounds of
> regression passes for me without any issue. Please let me know if it works
> for you.
>

Hi Pavan,

Today i was playing with your patch and running some tests and found
some problems i wanted to report before i forget them ;)

* You need to add a prototype in src/backend/utils/adt/pgstatfuncs.c:
extern Datum pg_stat_get_tuples_warm_updated(PG_FUNCTION_ARGS);

* The isolation test for partial_index fails (attached the regression.diffs)

* running a home-made test i have at hand i got this assertion:
"""
TRAP: FailedAssertion("!(buf_state & (1U << 24))", File: "bufmgr.c", Line: 837)
LOG: server process (PID 18986) was terminated by signal 6: Aborted
"""
To reproduce:
1) run prepare_test.sql
2) then run the following pgbench command (sql scripts attached):
pgbench -c 24 -j 24 -T 600 -n -f inserts(dot)sql(at)15 -f updates_1(dot)sql(at)20 -f
updates_2(dot)sql(at)20 -f deletes(dot)sql(at)45 db_test

* sometimes when i have made the server crash the attempt to recovery
fails with this assertion:
"""
LOG: database system was not properly shut down; automatic recovery in progress
LOG: redo starts at 0/157F970
TRAP: FailedAssertion("!(!warm_update)", File: "heapam.c", Line: 8924)
LOG: startup process (PID 14031) was terminated by signal 6: Aborted
LOG: aborting startup due to startup process failure
"""
still cannot reproduce this one consistently but happens often enough

will continue playing with it...

--
Jaime Casanova www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
regression.diffs application/octet-stream 6.7 KB
deletes.sql application/sql 253 bytes
inserts.sql application/sql 98 bytes
prepare_test.sql application/sql 453 bytes
updates_1.sql application/sql 263 bytes
updates_2.sql application/sql 286 bytes

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