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| author | Andres Freund <andres@anarazel.de> | 2017-05-06 16:47:40 -0700 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2017-05-06 16:55:07 -0700 |
| commit | e6c44eef55cda493c759e926cecceb92186159b8 (patch) | |
| tree | 96f6da115893bd9bbd4d7c4e1def1337c4cecdd3 /src/backend/postmaster/checkpointer.c | |
| parent | 334b82cd56a65e09154d9f930d35a761a9c5cfab (diff) | |
| download | postgresql-e6c44eef55cda493c759e926cecceb92186159b8.tar.gz postgresql-e6c44eef55cda493c759e926cecceb92186159b8.zip | |
Fix off-by-one possibly leading to skipped XLOG_RUNNING_XACTS records.
Since 6ef2eba3f57f1 ("Skip checkpoints, archiving on idle systems."),
GetLastImportantRecPtr() is used to avoid performing superfluous
checkpoints, xlog switches, running-xact records when the system is
idle. Unfortunately the check concerning running-xact records had a
off-by-one error, leading to such records being potentially skipped
when only a single record has been inserted since the last
running-xact record.
An alternative approach would have been to change
GetLastImportantRecPtr()'s definition to point to the end of records,
but that would make the checkpoint code more complicated.
Author: Andres Freund
Discussion: https://postgr.es/m/20170505012447.wsrympaxnfis6ojt@alap3.anarazel.de
Backpatch: no, code only present in master
Diffstat (limited to 'src/backend/postmaster/checkpointer.c')
| -rw-r--r-- | src/backend/postmaster/checkpointer.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index fe9041f748c..d12db0d5a7b 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -611,7 +611,8 @@ CheckArchiveTimeout(void) { /* * Switch segment only when "important" WAL has been logged since the - * last segment switch. + * last segment switch (last_switch_lsn points to end of segment + * switch occurred in). */ if (GetLastImportantRecPtr() > last_switch_lsn) { |