Re: Slot's restart_lsn may point to removed WAL segment after hard restart unexpectedly

On Thursday, November 21, 2024 17:56 MSK, "Vitaly Davydov" <v(dot)davydov(at)postgrespro(dot)ru> wrote:

> I'm trying to create a perl test to reproduce it. Please, give me some time to create the test script.

Attached is the test script which reproduces my problem. It should be run on a patched postgresql with the following changes (see below). It is the easiest way to emulate long checkpoint during high load.

CheckPointBuffers(int flags)
{
BufferSync(flags);
+ pg_usleep(10000000);
}

I used the following command line to run the script, where <postgresqldir> - the directory with postgresql sources. The module IPC::Run should be installed as well. PATH and LD_LIBRARY_PATH should be set to a proper postgresql binary and libraries as well.

perl -I <postgresqldir>/src/test/perl/ restartlsn.pl

Finally, it should produce the following error into the log:

error running SQL: 'psql:<stdin>:1: ERROR: requested WAL segment pg_wal/000000010000000000000001 has already been removed'

With best regards,
Vitaly