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Fix concurrent indexing operations with temporary tables

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Attempting to use CREATE INDEX, DROP INDEX or REINDEX with CONCURRENTLY
on a temporary relation with ON COMMIT actions triggered unexpected
errors because those operations use multiple transactions internally to
complete their work.  Here is for example one confusing error when using
ON COMMIT DELETE ROWS:
ERROR:  index "foo" already contains data

Issues related to temporary relations and concurrent indexing are fixed
in this commit by enforcing the non-concurrent path to be taken for
temporary relations even if using CONCURRENTLY, transparently to the
user.  Using a non-concurrent path does not matter in practice as locks
cannot be taken on a temporary relation by a session different than the
one owning the relation, and the non-concurrent operation is more
effective.

The problem exists with REINDEX since v12 with the introduction of
CONCURRENTLY, and with CREATE/DROP INDEX since CONCURRENTLY exists for
those commands.  In all supported versions, this caused only confusing
error messages to be generated.  Note that with REINDEX, it was also
possible to issue a REINDEX CONCURRENTLY for a temporary relation owned
by a different session, leading to a server crash.

The idea to enforce transparently the non-concurrent code path for
temporary relations comes originally from Andres Freund.

Reported-by: Manuel Rigger
Author: Michael Paquier, Heikki Linnakangas
Reviewed-by: Andres Freund, Álvaro Herrera, Heikki Linnakangas
Discussion: https://postgr.es/m/CA+u7OA6gP7YAeCguyseusYcc=uR8+ypjCcgDDCTzjQ+k6S9ksQ@mail.gmail.com
Backpatch-through: 9.4
This commit is contained in:
Michael Paquier
2020-01-22 09:49:18 +09:00
parent 9b9c5f279e
commit a904abe2e2
8 changed files with 235 additions and 13 deletions
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9
src/backend/catalog/index.c
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@@ -2016,6 +2016,15 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
LOCKTAG heaplocktag;
LOCKMODE lockmode;
/*
* A temporary relation uses a non-concurrent DROP. Other backends can't
* access a temporary relation, so there's no harm in grabbing a stronger
* lock (see comments in RemoveRelations), and a non-concurrent DROP is
* more efficient.
*/
Assert(get_rel_persistence(indexId) != RELPERSISTENCE_TEMP ||
(!concurrent && !concurrent_lock_mode));
/*
* To drop an index safely, we must grab exclusive lock on its parent
* table. Exclusive lock on the index alone is insufficient because