Subject: [PATCH v5 3/7] Propagate changes to indisclustered to child/parents

From: Justin Pryzby <[email-masked]>
Date: Tue, 6 Oct 2020 22:11:12 -0500

---
 src/backend/commands/cluster.c        | 109 ++++++++++++++++----------
 src/backend/commands/indexcmds.c      |   2 +
 src/test/regress/expected/cluster.out |  46 +++++++++++
 src/test/regress/sql/cluster.sql      |  11 +++
 4 files changed, 125 insertions(+), 43 deletions(-)

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 391e018bbd..4f30174ba7 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -73,6 +73,7 @@ static void rebuild_relation(Relation OldHeap, Oid indexOid, bool verbose);
 static void copy_table_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
 							bool verbose, bool *pSwapToastByContent,
 							TransactionId *pFreezeXid, MultiXactId *pCutoffMulti);
+static void set_indisclustered(Oid indexOid, bool isclustered, Relation pg_index);
 static List *get_tables_to_cluster(MemoryContext cluster_context);
 static List *get_tables_to_cluster_partitioned(MemoryContext cluster_context,
 		Oid indexOid);
@@ -489,66 +490,88 @@ check_index_is_clusterable(Relation OldHeap, Oid indexOid, bool recheck, LOCKMOD
 	index_close(OldIndex, NoLock);
 }
 
+/*
+ * Helper for mark_index_clustered
+ * Mark a single index as clustered or not.
+ * pg_index is passed by caller to avoid repeatedly re-opening it.
+ */
+static void
+set_indisclustered(Oid indexOid, bool isclustered, Relation pg_index)
+{
+	HeapTuple	indexTuple;
+	Form_pg_index indexForm;
+
+	indexTuple = SearchSysCacheCopy1(INDEXRELID,
+									ObjectIdGetDatum(indexOid));
+	if (!HeapTupleIsValid(indexTuple))
+		elog(ERROR, "cache lookup failed for index %u", indexOid);
+	indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
+
+	/* this was checked earlier, but let's be real sure */
+	if (isclustered && !indexForm->indisvalid)
+		elog(ERROR, "cannot cluster on invalid index %u", indexOid);
+
+	indexForm->indisclustered = isclustered;
+	CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
+	heap_freetuple(indexTuple);
+}
+
 /*
  * mark_index_clustered: mark the specified index as the one clustered on
  *
- * With indexOid == InvalidOid, will mark all indexes of rel not-clustered.
+ * With indexOid == InvalidOid, mark all indexes of rel not-clustered.
+ * Otherwise, mark children of the clustered index as clustered, and parents of
+ * other indexes as unclustered.
+ * We wish to maintain the following properties:
+ * 1) Only one index on a relation can be marked clustered at once
+ * 2) If a partitioned index is clustered, then all its children must be
+ *     clustered.
  */
 void
 mark_index_clustered(Relation rel, Oid indexOid, bool is_internal)
 {
-	HeapTuple	indexTuple;
-	Form_pg_index indexForm;
-	Relation	pg_index;
-	ListCell   *index;
-
-	/*
-	 * If the index is already marked clustered, no need to do anything.
-	 */
-	if (OidIsValid(indexOid))
-	{
-		if (get_index_isclustered(indexOid))
-			return;
-	}
+	ListCell	*lc, *lc2;
+	List		*indexes;
+	Relation	pg_index = table_open(IndexRelationId, RowExclusiveLock);
+	List		*inh = find_all_inheritors(RelationGetRelid(rel), ShareRowExclusiveLock, NULL);
 
 	/*
 	 * Check each index of the relation and set/clear the bit as needed.
+	 * Iterate over the relation's children rather than the index's children
+	 * since we need to unset cluster for indexes on intermediate children,
+	 * too.
 	 */
-	pg_index = table_open(IndexRelationId, RowExclusiveLock);
-
-	foreach(index, RelationGetIndexList(rel))
+	foreach(lc, inh)
 	{
-		Oid			thisIndexOid = lfirst_oid(index);
-
-		indexTuple = SearchSysCacheCopy1(INDEXRELID,
-										 ObjectIdGetDatum(thisIndexOid));
-		if (!HeapTupleIsValid(indexTuple))
-			elog(ERROR, "cache lookup failed for index %u", thisIndexOid);
-		indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
+		Oid			inhrelid = lfirst_oid(lc);
+		Relation	thisrel = table_open(inhrelid, ShareRowExclusiveLock);
 
-		/*
-		 * Unset the bit if set.  We know it's wrong because we checked this
-		 * earlier.
-		 */
-		if (indexForm->indisclustered)
+		indexes = RelationGetIndexList(thisrel);
+		foreach (lc2, indexes)
 		{
-			indexForm->indisclustered = false;
-			CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
-		}
-		else if (thisIndexOid == indexOid)
-		{
-			/* this was checked earlier, but let's be real sure */
-			if (!indexForm->indisvalid)
-				elog(ERROR, "cannot cluster on invalid index %u", indexOid);
-			indexForm->indisclustered = true;
-			CatalogTupleUpdate(pg_index, &indexTuple->t_self, indexTuple);
-		}
+			bool	isclustered;
+			Oid		thisIndexOid = lfirst_oid(lc2);
+			List	*parentoids = get_rel_relispartition(thisIndexOid) ?
+				get_partition_ancestors(thisIndexOid) : NIL;
 
-		InvokeObjectPostAlterHookArg(IndexRelationId, thisIndexOid, 0,
-									 InvalidOid, is_internal);
+			/*
+			 * A child of the clustered index must be set clustered;
+			 * indexes which are not children of the clustered index are
+			 * set unclustered
+			 */
+			isclustered = (thisIndexOid == indexOid) ||
+					list_member_oid(parentoids, indexOid);
+			Assert(OidIsValid(indexOid) || !isclustered);
+			set_indisclustered(thisIndexOid, isclustered, pg_index);
+
+			InvokeObjectPostAlterHookArg(IndexRelationId, thisIndexOid, 0,
+										 InvalidOid, is_internal);
+		}
 
-		heap_freetuple(indexTuple);
+		list_free(indexes);
+		table_close(thisrel, ShareRowExclusiveLock);
 	}
+	list_free(inh);
 
 	table_close(pg_index, RowExclusiveLock);
 }
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index ca24620fd0..cd9ca1beff 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -25,6 +25,7 @@
 #include "catalog/catalog.h"
 #include "catalog/index.h"
 #include "catalog/indexing.h"
+#include "catalog/partition.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_inherits.h"
@@ -32,6 +33,7 @@
 #include "catalog/pg_opfamily.h"
 #include "catalog/pg_tablespace.h"
 #include "catalog/pg_type.h"
+#include "commands/cluster.h"
 #include "commands/comment.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/expected/cluster.out b/src/test/regress/expected/cluster.out
index e4448350e7..a9fb9f1021 100644
--- a/src/test/regress/expected/cluster.out
+++ b/src/test/regress/expected/cluster.out
@@ -495,6 +495,52 @@ Indexes:
     "clstrpart_idx" btree (a) CLUSTER
 Number of partitions: 3 (Use \d+ to list them.)
 
+-- Test that it recurses to grandchildren:
+\d clstrpart33
+            Table "public.clstrpart33"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+Partition of: clstrpart3 DEFAULT
+Indexes:
+    "clstrpart33_a_idx" btree (a) CLUSTER
+
+ALTER TABLE clstrpart SET WITHOUT CLUSTER;
+\d clstrpart33
+            Table "public.clstrpart33"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+Partition of: clstrpart3 DEFAULT
+Indexes:
+    "clstrpart33_a_idx" btree (a)
+
+ALTER TABLE clstrpart CLUSTER ON clstrpart_idx;
+\d clstrpart33
+            Table "public.clstrpart33"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+Partition of: clstrpart3 DEFAULT
+Indexes:
+    "clstrpart33_a_idx" btree (a) CLUSTER
+
+-- Check that only one child is marked clustered after marking clustered on a different parent
+CREATE INDEX clstrpart1_idx_2 ON clstrpart1(a);
+ALTER TABLE clstrpart CLUSTER ON clstrpart_idx;
+ALTER TABLE clstrpart1 CLUSTER ON clstrpart1_idx_2;
+\d clstrpart1
+       Partitioned table "public.clstrpart1"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+Partition of: clstrpart FOR VALUES FROM (1) TO (10)
+Partition key: RANGE (a)
+Indexes:
+    "clstrpart1_a_idx" btree (a)
+    "clstrpart1_idx_2" btree (a) CLUSTER
+Number of partitions: 2 (Use \d+ to list them.)
+
 -- Test CLUSTER with external tuplesorting
 create table clstr_4 as select * from tenk1;
 create index cluster_sort on clstr_4 (hundred, thousand, tenthous);
diff --git a/src/test/regress/sql/cluster.sql b/src/test/regress/sql/cluster.sql
index 22225dc924..d15bd51496 100644
--- a/src/test/regress/sql/cluster.sql
+++ b/src/test/regress/sql/cluster.sql
@@ -220,6 +220,17 @@ CLUSTER clstrpart1 USING clstrpart1_a_idx; -- partition which is itself partitio
 CLUSTER clstrpart12 USING clstrpart12_a_idx; -- partition which is itself partitioned, no childs
 CLUSTER clstrpart2 USING clstrpart2_a_idx; -- leaf
 \d clstrpart
+-- Test that it recurses to grandchildren:
+\d clstrpart33
+ALTER TABLE clstrpart SET WITHOUT CLUSTER;
+\d clstrpart33
+ALTER TABLE clstrpart CLUSTER ON clstrpart_idx;
+\d clstrpart33
+-- Check that only one child is marked clustered after marking clustered on a different parent
+CREATE INDEX clstrpart1_idx_2 ON clstrpart1(a);
+ALTER TABLE clstrpart CLUSTER ON clstrpart_idx;
+ALTER TABLE clstrpart1 CLUSTER ON clstrpart1_idx_2;
+\d clstrpart1
 
 -- Test CLUSTER with external tuplesorting
 
-- 
2.17.0

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