postgres

History

Robert Haas 08c1795c52 Update the documentation on recovering from (M)XID exhaustion. The old documentation encourages entering single-user mode for no reason, which is a bad plan in most cases. Instead, discourage users from doing that, and explain the limited cases in which it may be desirable. The old documentation claims that running VACUUM as anyone but the superuser can't possibly work, which is not really true, because it might be that some other user has enough permissions to VACUUM all the tables that matter. Weaken the language just a bit. The old documentation claims that you can't run any commands when near XID exhaustion, which is false because you can still run commands that don't require an XID, like a SELECT without a locking clause. The old documentation doesn't clearly explain that it's a good idea to get rid of prepared transactons, long-running transactions, and replication slots that are preventing (M)XID horizon advancement. Spell out the steps to do that. Also, discourage the use of VACUUM FULL and VACUUM FREEZE in this type of scenario. Back-patch to v14. Much of this is good advice on all supported versions, but before `60f1f09ff4` the chances of VACUUM failing in multi-user mode were much higher. Alexander Alekseev, John Naylor, Robert Haas, reviewed at various times by Peter Geoghegan, Hannu Krosing, and Andres Freund. Discussion: http://postgr.es/m/CA+TgmoYtsUDrzaHcmjFhLzTk1VEv29mO_u-MT+XWHrBJ_4nD8A@mail.gmail.com	2 years ago
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sgml	Update the documentation on recovering from (M)XID exhaustion.	2 years ago
Makefile	…

Robert Haas 08c1795c52 Update the documentation on recovering from (M)XID exhaustion.

The old documentation encourages entering single-user mode for no
reason, which is a bad plan in most cases. Instead, discourage users
from doing that, and explain the limited cases in which it may be
desirable.

The old documentation claims that running VACUUM as anyone but the
superuser can't possibly work, which is not really true, because it
might be that some other user has enough permissions to VACUUM all
the tables that matter. Weaken the language just a bit.

The old documentation claims that you can't run any commands
when near XID exhaustion, which is false because you can still
run commands that don't require an XID, like a SELECT without a
locking clause.

The old documentation doesn't clearly explain that it's a good idea
to get rid of prepared transactons, long-running transactions, and
replication slots that are preventing (M)XID horizon advancement.
Spell out the steps to do that.

Also, discourage the use of VACUUM FULL and VACUUM FREEZE in
this type of scenario.

Back-patch to v14. Much of this is good advice on all supported
versions, but before 60f1f09ff4
the chances of VACUUM failing in multi-user mode were much higher.

Alexander Alekseev, John Naylor, Robert Haas, reviewed at various
times by Peter Geoghegan, Hannu Krosing, and Andres Freund.

Discussion: http://postgr.es/m/CA+TgmoYtsUDrzaHcmjFhLzTk1VEv29mO_u-MT+XWHrBJ_4nD8A@mail.gmail.com

2 years ago

sgml Update the documentation on recovering from (M)XID exhaustion. 2 years ago

Makefile

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