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Acquire properly session-level lock on new index in REINDEX CONCURRENTLY

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In the first transaction run for REINDEX CONCURRENTLY, a thinko in the
existing logic caused two session locks to be taken on the old index,
causing the session lock on the newly-created index to be missed.  This
made possible concurrent DDL commands (like ALTER INDEX) on the new
index while REINDEX CONCURRENTLY was processing from the point where the
first internal transaction committed.

This issue has been discovered while digging into another bug.

Author: Michael Paquier
Discussion: https://postgr.es/m/20191021074323.GB1869@paquier.xyz
Backpatch-through: 12
This commit is contained in:
Michael Paquier 2019-10-23 15:04:48 +09:00
parent 508e84d799
commit 5d3500da72
1 changed files with 5 additions and 2 deletions
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7
src/backend/commands/indexcmds.c
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@ -2960,8 +2960,11 @@ ReindexRelationConcurrently(Oid relationOid, int options)
indexId,
concurrentName);
/* Now open the relation of the new index, a lock is also needed on it */
newIndexRel = index_open(indexId, ShareUpdateExclusiveLock);
/*
* Now open the relation of the new index, a session-level lock is
* also needed on it.
*/
newIndexRel = index_open(newIndexId, ShareUpdateExclusiveLock);
/*
* Save the list of OIDs and locks in private context