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| author | Noah Misch <noah@leadboat.com> | 2020-08-01 15:31:01 -0700 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2020-08-01 15:31:01 -0700 |
| commit | cd5e82256de5895595cdd99ecb03aea15b346f71 (patch) | |
| tree | 747def403ed87cd47308b611a7cb99eccab6db8d /doc/src | |
| parent | 9f9682783bea74bf8d93cac4f7dd65fa677f5dc7 (diff) | |
| download | postgresql-cd5e82256de5895595cdd99ecb03aea15b346f71.tar.gz postgresql-cd5e82256de5895595cdd99ecb03aea15b346f71.zip | |
Change XID and mxact limits to warn at 40M and stop at 3M.
We have edge-case bugs when assigning values in the last few dozen pages
before the wrap limit. We may introduce similar bugs in the future. At
default BLCKSZ, this makes such bugs unreachable outside of single-user
mode. Also, when VACUUM began to consume mxacts, multiStopLimit did not
change to compensate.
pg_upgrade may fail on a cluster that was already printing "must be
vacuumed" warnings. Follow the warning's instructions to clear the
warning, then run pg_upgrade again. One can still, peacefully consume
98% of XIDs or mxacts, so DBAs need not change routine VACUUM settings.
Discussion: https://postgr.es/m/20200621083513.GA3074645@rfd.leadboat.com
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/maintenance.sgml | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml index 4acdd15d4b3..de0794adeb9 100644 --- a/doc/src/sgml/maintenance.sgml +++ b/doc/src/sgml/maintenance.sgml @@ -608,10 +608,10 @@ SELECT datname, age(datfrozenxid) FROM pg_database; <para> If for some reason autovacuum fails to clear old XIDs from a table, the system will begin to emit warning messages like this when the database's - oldest XIDs reach eleven million transactions from the wraparound point: + oldest XIDs reach forty million transactions from the wraparound point: <programlisting> -WARNING: database "mydb" must be vacuumed within 10985967 transactions +WARNING: database "mydb" must be vacuumed within 39985967 transactions HINT: To avoid a database shutdown, execute a database-wide VACUUM in that database. </programlisting> @@ -621,7 +621,7 @@ HINT: To avoid a database shutdown, execute a database-wide VACUUM in that data be able to advance the database's <structfield>datfrozenxid</structfield>.) If these warnings are ignored, the system will shut down and refuse to start any new - transactions once there are fewer than 1 million transactions left + transactions once there are fewer than three million transactions left until wraparound: <programlisting> @@ -629,7 +629,7 @@ ERROR: database is not accepting commands to avoid wraparound data loss in data HINT: Stop the postmaster and vacuum that database in single-user mode. </programlisting> - The 1-million-transaction safety margin exists to let the + The three-million-transaction safety margin exists to let the administrator recover without data loss, by manually executing the required <command>VACUUM</command> commands. However, since the system will not execute commands once it has gone into the safety shutdown mode, |