Feedback-ID: i0fe9450f:Fastmail
Date: Tue, 10 Mar 2026 19:28:29 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Xuneng Zhou <xunengzhou@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@lists.postgresql.org>,
	Nazir Bilal Yavuz <byavuz81@gmail.com>
Subject: Re: Streamify more code paths
Message-ID: <aa_yTTUpxOCFdQ2x@paquier.xyz>
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On Tue, Mar 10, 2026 at 02:06:12PM +0800, Xuneng Zhou wrote:
> Here=E2=80=99s v5 of the patchset. The wal_logging_large patch has been
> removed, as no performance gains were observed in the benchmark runs.

Looking at the numbers you are posting, it is harder to get excited
about the hash, gin, bloom_vacuum and wal_logging.  The worker method
seems more efficient, may show that we are out of noise level.

The results associated to pgstattuple and the bloom scans are on a
different level for the three methods.

Saying that, it is really nice that you have sent the benchmark.  The
measurement method looks in line with the goal here after review (IO
stats, calculations), and I have taken some time to run it to get an
idea of the difference for these five code paths, as of (slightly
edited the script for my own environment, result is the same):
=2E/run_streaming_benchmark --baseline --io-method=3Dio_uring/worker

I am not much interested in the sync case, so I have tested the two
other methods:

1) method=3DIO-uring
bloom_scan_large           base=3D   725.3ms  patch=3D    99.9ms   7.26x
( 86.2%)  (reads=3D19676->1294, io_time=3D688.36->33.69ms)
bloom_vacuum_large         base=3D  7414.9ms  patch=3D  7455.2ms   0.99x
( -0.5%)  (reads=3D48361->11597, io_time=3D459.02->257.51ms)
pgstattuple_large          base=3D 12642.9ms  patch=3D 11873.5ms   1.06x
(  6.1%)  (reads=3D206945->12983, io_time=3D6516.70->143.46ms)
gin_vacuum_large           base=3D  3546.8ms  patch=3D  2317.9ms   1.53x
( 34.6%)  (reads=3D20734->17735, io_time=3D3244.40->2021.53ms)
hash_vacuum_large          base=3D 12268.5ms  patch=3D 11751.1ms   1.04x
(  4.2%)  (reads=3D76677->15606, io_time=3D1483.10->315.03ms)
wal_logging_large          base=3D 33713.0ms  patch=3D 32773.9ms   1.03x
(  2.8%)  (reads=3D21641->21641, io_time=3D81.18->77.25ms)

2) method=3Dworker io-workers=3D3
bloom_scan_large           base=3D   725.0ms  patch=3D   465.7ms   1.56x
( 35.8%)  (reads=3D19676->1294, io_time=3D688.70->52.20ms)
bloom_vacuum_large         base=3D  7138.3ms  patch=3D  7156.0ms   1.00x
( -0.2%)  (reads=3D48361->11597, io_time=3D284.56->64.37ms)
pgstattuple_large          base=3D 12429.3ms  patch=3D 11916.8ms   1.04x
(  4.1%)  (reads=3D206945->12983, io_time=3D6501.91->32.24ms)
gin_vacuum_large           base=3D  3769.4ms  patch=3D  3716.7ms   1.01x
(  1.4%)  (reads=3D20775->17684, io_time=3D3562.21->3528.14ms)
hash_vacuum_large          base=3D 11750.1ms  patch=3D 11289.0ms   1.04x
(  3.9%)  (reads=3D76677->15606, io_time=3D1296.03->98.72ms)
wal_logging_large          base=3D 32862.3ms  patch=3D 33179.7ms   0.99x
( -1.0%)  (reads=3D21641->21641, io_time=3D91.42->90.59ms)=20

The bloom scan case is a winner in runtime for both cases, and in
terms of stats we get much better numbers for all of them.  These feel
rather in line with what you have, except for pgstattuple's runtime,
still its IO numbers feel good.  That's just to say that I'll review
them and try to do something about at least some of the pieces for
this release.
--
Michael

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