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Preserve clustered index after rewrites with ALTER TABLE

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A table rewritten by ALTER TABLE would lose tracking of an index usable
for CLUSTER.  This setting is tracked by pg_index.indisclustered and is
controlled by ALTER TABLE, so some extra work was needed to restore it
properly.  Note that ALTER TABLE only marks the index that can be used
for clustering, and does not do the actual operation.

Author: Amit Langote, Justin Pryzby
Reviewed-by: Ibrar Ahmed, Michael Paquier
Discussion: https://postgr.es/m/20200202161718.GI13621@telsasoft.com
Backpatch-through: 9.5
This commit is contained in:
Michael Paquier
2020-04-06 11:05:47 +09:00
parent 23a0cf2c9f
commit 3e62dd3a93
5 changed files with 143 additions and 0 deletions
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23
src/backend/utils/cache/lsyscache.c vendored
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@ -3273,3 +3273,26 @@ get_index_isvalid(Oid index_oid)
return isvalid;
}
/*
* get_index_isclustered
*
* Given the index OID, return pg_index.indisclustered.
*/
bool
get_index_isclustered(Oid index_oid)
{
bool isclustered;
HeapTuple tuple;
Form_pg_index rd_index;
tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for index %u", index_oid);
rd_index = (Form_pg_index) GETSTRUCT(tuple);
isclustered = rd_index->indisclustered;
ReleaseSysCache(tuple);
return isclustered;
}