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From: Thomas Munro <thomas.munro@gmail.com>
Date: Sat, 7 Sep 2024 10:27:27 +1200
Message-ID: <CA+hUKGLRKoED72qWOLfO-u6D6BxdDvf_t9ekC08vTF5SumEEEQ@mail.gmail.com>
Subject: Re: Trying out read streams in pgvector (an extension)
To: "Jonathan S. Katz" <jkatz@postgresql.org>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
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There was a mistake in my query, so the macOS speedup column was wrong
(was accidentally comparing Linux number with macOS master, sorry for
the noise).  I also forgot to mention that you don't actually get the
speedup on PostgreSQL 17 on a Mac, because Peter only recently
implemented the needed read-ahead support for macOS in master/18, but
it doesn't get slower.  Here's the corrected table:

              |     linux (xfs)           |  macos (apfs)
 branch | eic |  avg   | speedup | stdev  |  avg   | speedup | stdev
--------+-----+--------+---------+--------+--------+---------+--------
 master |     | 73.959 |     1.0 | 24.168 | 72.290 |     1.0 | 11.851
 stream |   0 | 70.117 |     1.1 | 36.699 | 76.289 |     0.9 | 12.742
 stream |   1 | 57.983 |     1.3 |  5.845 | 79.969 |     0.9 |  8.308
 stream |   2 | 35.629 |     2.1 |  4.088 | 49.198 |     1.5 |  7.686
 stream |   3 | 28.477 |     2.6 |  2.607 | 37.540 |     1.9 |  5.272
 stream |   4 | 26.493 |     2.8 |  3.691 | 33.014 |     2.2 |  4.444
 stream |   5 | 23.711 |     3.1 |  2.435 | 32.622 |     2.2 |  2.270
 stream |   6 | 22.885 |     3.2 |  1.908 | 31.254 |     2.3 |  4.170
 stream |   7 | 21.910 |     3.4 |  2.153 | 33.669 |     2.1 |  4.616
 stream |   8 | 20.741 |     3.6 |  1.594 | 34.182 |     2.1 |  3.819
 stream |   9 | 22.471 |     3.3 |  3.094 | 30.690 |     2.4 |  2.677
 stream |  10 | 19.895 |     3.7 |  1.695 | 32.631 |     2.2 |  4.976
 stream |  11 | 19.447 |     3.8 |  1.647 | 31.163 |     2.3 |  3.351
 stream |  12 | 18.658 |     4.0 |  1.503 | 30.817 |     2.3 |  3.538
 stream |  13 | 18.886 |     3.9 |  0.874 | 29.184 |     2.5 |  4.832
 stream |  14 | 18.667 |     4.0 |  1.692 | 28.783 |     2.5 |  3.459
 stream |  15 | 19.080 |     3.9 |  1.429 | 28.928 |     2.5 |  3.396
 stream |  16 | 18.929 |     3.9 |  3.469 | 29.282 |     2.5 |  2.868