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Mark commit and abort WAL records with XLR_SPECIAL_REL_UPDATE.

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If a commit or abort record includes "dropped relfilenodes", then replaying
the record will remove data files. That is surely a "special rel update",
but the records were not marked as such. Fix that, teach pg_rewind to
expect and ignore them, and add a test case to cover it.

It's always been like this, but no backporting for fear of breaking
existing applications. If an application parsed the WAL but was not
handling commit/abort records, it would stop working. That might be a good
thing if it really needed to handle the dropped rels, but it will be caught
when the application is updated to work with PostgreSQL v14 anyway.

Discussion: https://www.postgresql.org/message-id/07b33e2c-46a6-86a1-5f9e-a7da73fddb95%40iki.fi
Reviewed-by: Amit Kapila, Michael Paquier
This commit is contained in:
Heikki Linnakangas
2020-08-17 10:52:58 +03:00
parent 3941eb6341
commit a28d731a11
3 changed files with 29 additions and 1 deletions
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2
src/backend/access/transam/xact.c
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@ -5565,6 +5565,7 @@ XactLogCommitRecord(TimestampTz commit_time,
{
xl_xinfo.xinfo |= XACT_XINFO_HAS_RELFILENODES;
xl_relfilenodes.nrels = nrels;
info |= XLR_SPECIAL_REL_UPDATE;
}
if (nmsgs > 0)
@ -5697,6 +5698,7 @@ XactLogAbortRecord(TimestampTz abort_time,
{
xl_xinfo.xinfo |= XACT_XINFO_HAS_RELFILENODES;
xl_relfilenodes.nrels = nrels;
info |= XLR_SPECIAL_REL_UPDATE;
}
if (TransactionIdIsValid(twophase_xid))