Re: speed up a logical replica setup

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Alexander Lakhin <exclusion@gmail.com>

Cc: Peter Eisentraut <peter@eisentraut.org>, Euler Taveira <euler@eulerto.com>, Amit Kapila <amit.kapila16@gmail.com>, Shlok Kyal <shlok.kyal.oss@gmail.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Fabrízio de Royes Mello <fabriziomello@gmail.com>, vignesh C <vignesh21@gmail.com>

Date: 2024-06-30T16:59:54Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

pg_createsubscriber: Remove obsolete comment
- 71795d1cb41b 17.0 landed
- 1330843bb78e 18.0 landed
pg_createsubscriber: Fix an unpredictable recovery wait time.
- e5ba6a5ab62c 17.0 landed
- 03b08c8f5f3e 18.0 landed
Fix unstable test in 040_pg_createsubscriber.
- ae4e072bad5f 17.0 landed
- 9fd8b331dfe1 18.0 landed
Fix the testcase introduced in commit 81d20fbf7a.
- ae395f0f7edb 18.0 landed
- 14387ab06503 17.0 landed
Further weaken new pg_createsubscriber test on Windows.
- 55c309fc5b08 17.0 landed
- a1333ec048fb 18.0 landed
Temporarily(?) weaken new pg_createsubscriber test on Windows.
- 54508209178b 17.0 landed
Make pg_createsubscriber warn if publisher has two-phase commit enabled.
- 917754557cc0 17.0 landed
Make pg_createsubscriber more wary about quoting connection parameters.
- b3f5ccebd79d 17.0 landed
pg_createsubscriber: Remove failover replication slots on subscriber
- 81d20fbf7a03 17.0 landed
pg_createsubscriber: Remove replication slot check on primary
- b96391382626 17.0 landed
pg_createsubscriber: Only --recovery-timeout controls the end of recovery process
- 04c8634c0c4d 17.0 landed
pg_createsubscriber: creates a new logical replica from a standby server
- d44032d01463 17.0 landed
Add some const decorations
- 48018f1d8c12 17.0 landed
Add option force_initdb to PostgreSQL::Test::Cluster:init()
- ff9e1e764fcc 17.0 cited
Remove MSVC scripts
- 1301c80b2167 17.0 cited

Alexander Lakhin <exclusion@gmail.com> writes:
> As a recent buildfarm failure [1] shows, that test addition introduced
> new instability:

I have a different but possibly-related complaint: why is
040_pg_createsubscriber.pl so miserably slow?  On my machine it
runs for a bit over 19 seconds, which seems completely out of line
(for comparison, 010_pg_basebackup.pl takes 6 seconds, and the
other test scripts in this directory take much less).  It looks
like most of the blame falls on this step:

[12:47:22.292](14.534s) ok 28 - run pg_createsubscriber on node S

AFAICS the amount of data being replicated is completely trivial,
so that it doesn't make any sense for this to take so long --- and
if it does, that suggests that this tool will be impossibly slow
for production use.  But I suspect there is a logic flaw causing
this.  Speculating wildly, perhaps that is related to the failure
Alexander spotted?

			regards, tom lane