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Improve handling of dropped relations for REINDEX DATABASE/SCHEMA/SYSTEM

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When multiple relations are reindexed, a scan of pg_class is done first
to build the list of relations to work on.  However the REINDEX logic
has never checked if a relation listed still exists when beginning the
work on it, causing for example sudden cache lookup failures.

This commit adds safeguards against dropped relations for REINDEX,
similarly to VACUUM or CLUSTER where we try to open the relation,
ignoring it if it is missing.  A new option is added to the REINDEX
routines to control if a missed relation is OK to ignore or not.

An isolation test, based on REINDEX SCHEMA, is added for the concurrent
and non-concurrent cases.

Author: Michael Paquier
Reviewed-by: Anastasia Lubennikova
Discussion: https://postgr.es/m/20200813043805.GE11663@paquier.xyz
This commit is contained in:
Michael Paquier
2020-09-02 09:08:12 +09:00
parent 4c51a2d1e4
commit 1d65416661
8 changed files with 174 additions and 9 deletions
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34
src/backend/catalog/index.c
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@@ -3437,8 +3437,20 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
* Open and lock the parent heap relation. ShareLock is sufficient since
* we only need to be sure no schema or data changes are going on.
*/
heapId = IndexGetRelation(indexId, false);
heapRelation = table_open(heapId, ShareLock);
heapId = IndexGetRelation(indexId,
(options & REINDEXOPT_MISSING_OK) != 0);
/* if relation is missing, leave */
if (!OidIsValid(heapId))
return;
if ((options & REINDEXOPT_MISSING_OK) != 0)
heapRelation = try_table_open(heapId, ShareLock);
else
heapRelation = table_open(heapId, ShareLock);
/* if relation is gone, leave */
if (!heapRelation)
return;
if (progress)
{
@@ -3672,7 +3684,14 @@ reindex_relation(Oid relid, int flags, int options)
* to prevent schema and data changes in it. The lock level used here
* should match ReindexTable().
*/
rel = table_open(relid, ShareLock);
if ((options & REINDEXOPT_MISSING_OK) != 0)
rel = try_table_open(relid, ShareLock);
else
rel = table_open(relid, ShareLock);
/* if relation is gone, leave */
if (!rel)
return false;
/*
* This may be useful when implemented someday; but that day is not today.
@@ -3771,7 +3790,14 @@ reindex_relation(Oid relid, int flags, int options)
* still hold the lock on the main table.
*/
if ((flags & REINDEX_REL_PROCESS_TOAST) && OidIsValid(toast_relid))
result |= reindex_relation(toast_relid, flags, options);
{
/*
* Note that this should fail if the toast relation is missing, so
* reset REINDEXOPT_MISSING_OK.
*/
result |= reindex_relation(toast_relid, flags,
options & ~(REINDEXOPT_MISSING_OK));
}
return result;
}