Horton

Re: [HACKERS] WAL logging problem in 9.4.3?

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: robertmhaas@gmail.com
Cc: noah@leadboat.com, pgsql-hackers@postgresql.org, 9erthalion6@gmail.com, andrew.dunstan@2ndquadrant.com, hlinnaka@iki.fi, michael@paquier.xyz
Date: 2019-12-24T07:35:35Z
Lists: pgsql-hackers

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At Tue, 10 Dec 2019 16:59:25 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> shared_buffers=1GB/wal_buffers=16MB(defalut). pgbench -s 20 uses 256MB
> of storage so all of them can be loaded on shared memory.
> 
> The attached graph shows larger benefit in TPS drop and latency
> increase for HDD. The DDL pages at the corsspoint between commit-FPW
> and commit-sync moves from roughly 300 to 200 in TPS and latency, and
> 1000 to 600 in DDL runtime. If we can rely on the two graphs, 500 (or
> 512) pages seems to be the most promising candidate for the default
> value of wal_skip_threshold.
> regards.

I rebased the patch and changed the default value for the GUC variable
wal_skip_threshold to 4096 kilobytes in config.sgml, storage.c and
guc.c. 4096kB is choosed as it is the nice round number of 500 pages *
8kB = 4000kB.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

Commits

  1. Add perl2host call missing from a new test file.

  2. Skip WAL for new relfilenodes, under wal_level=minimal.

  3. Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

  4. Back-patch log_newpage_range().

  5. During heap rebuild, lock any TOAST index until end of transaction.

  6. In log_newpage_range(), heed forkNum and page_std arguments.

  7. Back-patch src/test/recovery and PostgresNode from 9.6 to 9.5.

  8. Reduce pg_ctl's reaction time when waiting for postmaster start/stop.

  9. Accelerate end-of-transaction dropping of relations

  10. Redesign the planner's handling of index-descent cost estimation.

  11. Make TRUNCATE do truncate-in-place when processing a relation that was created