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Message-ID: <fbc5d94e-6fbd-4a64-85d4-c9e284a58eb2@gmail.com>
Date: Sun, 15 Jun 2025 12:00:01 +0300
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Subject: Re: Slot's restart_lsn may point to removed WAL segment after hard
 restart unexpectedly
To: Alexander Korotkov <aekorotkov@gmail.com>,
 Vitaly Davydov <v.davydov@postgrespro.ru>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>,
 Masahiko Sawada <sawada.mshk@gmail.com>, tomas@vondra.me
References: <1d12d2-67235980-35-19a406a0@63439497>
 <CAA4eK1KMaPA5jir_SFu+qr3qu55OOdFWVZpuUkqTSGZ9fyPpHA@mail.gmail.com>
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 <CAA4eK1LmVoZ8jm5Jt3DERN9Z=y6L6xj5O0asw0smWw31Y8KfVw@mail.gmail.com>
 <CAPpHfdtp61pSt72KxxOnnV_Oj4OTAiKYCSTek0Pm87hVDod4Bg@mail.gmail.com>
 <CAA4eK1Lmd-stXWrNqX9iXugjY=ahhe7zRfyq+-vN512xvF4G2w@mail.gmail.com>
 <CAPpHfdsTiYQPywr4yeqVhUtA+eFdqisqcAOiTb+kiYhi9EVEvw@mail.gmail.com>
 <CAPpHfdvk-nfu5xzJyPArxWctofWPR+1L9uJ+yyWFA34n6b5rGQ@mail.gmail.com>
 <CAA4eK1Ladnm40UO-YC+c7eBYqjyFQSwg0dn1w_CiaMoBTsJUDA@mail.gmail.com>
 <CAPpHfduX--KKX853UwaJ8Cjo5bxbh19V_+McKQ3p9aS6b8T1Wg@mail.gmail.com>
 <CAA4eK1+VbBxYY-rG4B7Jq6TsYvdjt3d2nbUrs7p9-1sP5mH+sw@mail.gmail.com>
 <CAPpHfdvxqjE+RZdoOODQZAmQip6NpvSH40DuvVFWuf_00ek-yQ@mail.gmail.com>
 <1d97ec-6841b600-3-b7b4780@40747246>
 <CAA4eK1LvssAcp61qg957xRF0=K4xF0hfJQjQ6c9V7EGHSqraPg@mail.gmail.com>
 <28c8bf-68470780-3-51b29480@89454035>
 <CAPpHfdt77k3BqD=anh4b7UiRevfPOu2Hcf3rvSZXntxH+4G=Ug@mail.gmail.com>
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From: Alexander Lakhin <exclusion@gmail.com>
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Hello Alexander,

10.06.2025 23:14, Alexander Korotkov wrote:
> So, my proposal is to commit the attached patchset to the HEAD, and
> commit [1] to the back branches.  Any objections?

As the buildfarm animal prion shows [1], the 046_checkpoint_logical_slot
test fails with "-DRELCACHE_FORCE_RELEASE -DCATCACHE_FORCE_RELEASE":
# poll_query_until timed out executing this query:
#
#         SELECT count(*) > 0 FROM pg_stat_activity
#         WHERE backend_type = 'client backend' AND wait_event = 'logical-replication-slot-advance-segment'
#
# expecting this output:
# t
# last actual query output:
# f
# with stderr:
[04:16:27] t/046_checkpoint_logical_slot.pl ......
Dubious, test returned 29 (wstat 7424, 0x1d00)
No subtests run
[04:20:58] t/047_checkpoint_physical_slot.pl ..... ok   271294 ms ( 0.00 usr  0.00 sys +  0.37 cusr  0.26 csys =  0.63 CPU)

I'm able to reproduce this locally as well. Though the test passes for me
with the increased timeout, that is it's not stuck:
PG_TEST_TIMEOUT_DEFAULT=360 PROVE_TESTS="t/046*" make -s check -C src/test/recovery/
# +++ tap check in src/test/recovery +++
t/046_checkpoint_logical_slot.pl .. ok
All tests successful.
Files=1, Tests=1, 533 wallclock secs ( 0.01 usr  0.00 sys +  4.70 cusr  9.61 csys = 14.32 CPU)
Result: PASS

Could you have a look?

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prion&dt=2025-06-14%2001%3A58%3A06

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hello Alexander,<br>
      <br>
      10.06.2025 23:14, Alexander Korotkov wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAPpHfdt77k3BqD=anh4b7UiRevfPOu2Hcf3rvSZXntxH+4G=Ug@mail.gmail.com">
      <pre wrap="" class="moz-quote-pre">So, my proposal is to commit the attached patchset to the HEAD, and
commit [1] to the back branches.  Any objections?
</pre>
    </blockquote>
    <br>
    As the buildfarm animal prion shows [1], the
    046_checkpoint_logical_slot<br>
    test fails with "-DRELCACHE_FORCE_RELEASE -DCATCACHE_FORCE_RELEASE":<br>
    # poll_query_until timed out executing this query:<br>
    #<br>
    #         SELECT count(*) &gt; 0 FROM pg_stat_activity<br>
    #         WHERE backend_type = 'client backend' AND wait_event =
    'logical-replication-slot-advance-segment'<br>
    #     <br>
    # expecting this output:<br>
    # t<br>
    # last actual query output:<br>
    # f<br>
    # with stderr:<br>
    [04:16:27] t/046_checkpoint_logical_slot.pl ......<br>
    Dubious, test returned 29 (wstat 7424, 0x1d00)<br>
    No subtests run<br>
    [04:20:58] t/047_checkpoint_physical_slot.pl ..... ok   271294 ms (
    0.00 usr  0.00 sys +  0.37 cusr  0.26 csys =  0.63 CPU)<br>
    <br>
    I'm able to reproduce this locally as well. Though the test passes
    for me<br>
    with the increased timeout, that is it's not stuck:<br>
    PG_TEST_TIMEOUT_DEFAULT=360 PROVE_TESTS="t/046*" make -s check -C
    src/test/recovery/<br>
    # +++ tap check in src/test/recovery +++<br>
    t/046_checkpoint_logical_slot.pl .. ok<br>
    All tests successful.<br>
    Files=1, Tests=1, 533 wallclock secs ( 0.01 usr  0.00 sys +  4.70
    cusr  9.61 csys = 14.32 CPU)<br>
    Result: PASS<br>
    <br>
    Could you have a look?<br>
    <br>
    [1]
<a class="moz-txt-link-freetext" href="https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prion&amp;dt=2025-06-14%2001%3A58%3A06">https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prion&amp;dt=2025-06-14%2001%3A58%3A06</a><br>
    <br>
    Best regards,<br>
    Alexander<br>
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