Change the names generated for index partitions.

Instead of applying the default index-naming algorithm using the name
of the child partition, use the name of the parent partitioned index,
plus an underscore and some digit(s) as needed to make the name
unique.  This is similar to the rule adopted in commit 3db61db for
child foreign-key constraints.  As in that case, the immediate
motivation is to reduce the risk of index name collisions; but it
seems like this rule might be preferable from a user-experience
standpoint anyway.

Although these cases share code with CREATE TABLE LIKE ... INCLUDING
INDEXES, I kept the old behavior for CREATE TABLE LIKE.  It seems less
obvious that changing that would be a user-experience improvement,
since with CREATE TABLE LIKE there isn't any permanent connection of
the parent and child tables.  There is also a much larger
race-condition window for name collisions if we try to do this in
CREATE TABLE LIKE, since more time and indeed perhaps some other index
creations could occur before the actual index creation happens.
Finally, this is already a pretty big user-visible behavioral change;
not changing the much-longer-standing CREATE TABLE LIKE behavior
should reduce the blast radius a little bit.

Bug: #18959
Reported-by: Maximilian Chrzan <[email protected]>
Author: Tom Lane <[email protected]>
Discussion: https://postgr.es/m/[email protected]

Author: tglsfdc

contrib/btree_gist/expected/partitions.out

@@ -74,7 +74,7 @@ select * from parttmp_11_to_20 order by id, valid_at;
 -- make sure the excluson constraint excludes:
 insert into parttmp (id, valid_at) values
   (2, '[2000-01-15, 2000-02-01)');
-ERROR:  conflicting key value violates exclusion constraint "parttmp_1_to_10_id_valid_at_excl"
+ERROR:  conflicting key value violates exclusion constraint "parttmp_id_valid_at_excl_1"
 DETAIL:  Key (id, valid_at)=(2, [01-15-2000,02-01-2000)) conflicts with existing key (id, valid_at)=(2, [01-01-2000,02-01-2000)).
 drop table parttmp;
 -- should fail with a good error message:

contrib/pg_overexplain/expected/pg_overexplain.out

@@ -388,8 +388,8 @@ SELECT explain_filter($$
 EXPLAIN (BUFFERS OFF, COSTS OFF, SUMMARY OFF, TIMING OFF, ANALYZE, DEBUG)
 SELECT * FROM vegetables v1, vegetables v2 WHERE v1.id = v2.id;
 $$);
-                                      explain_filter                                      
-------------------------------------------------------------------------------------------
+                                        explain_filter                                        
+----------------------------------------------------------------------------------------------
  Nested Loop (actual rows=N.NN loops=1)
    Disabled Nodes: 0
    Parallel Safe: true
@@ -398,12 +398,12 @@ $$);
          Disabled Nodes: 0
          Parallel Safe: true
          Plan Node ID: 1
-         ->  Index Scan using brassica_id_idx on brassica v1_1 (actual rows=N.NN loops=1)
+         ->  Index Scan using vegetables_id_idx_1 on brassica v1_1 (actual rows=N.NN loops=1)
                Index Searches: 1
                Disabled Nodes: 0
                Parallel Safe: true
                Plan Node ID: 2
-         ->  Index Scan using daucus_id_idx on daucus v1_2 (actual rows=N.NN loops=1)
+         ->  Index Scan using vegetables_id_idx_2 on daucus v1_2 (actual rows=N.NN loops=1)
                Index Searches: 1
                Disabled Nodes: 0
                Parallel Safe: true
@@ -414,15 +414,15 @@ $$);
          Plan Node ID: 4
          extParam: 0
          allParam: 0
-         ->  Index Scan using brassica_id_idx on brassica v2_1 (actual rows=N.NN loops=8)
+         ->  Index Scan using vegetables_id_idx_1 on brassica v2_1 (actual rows=N.NN loops=8)
                Index Cond: (id = v1.id)
                Index Searches: 8
                Disabled Nodes: 0
                Parallel Safe: true
                Plan Node ID: 5
                extParam: 0
                allParam: 0
-         ->  Index Scan using daucus_id_idx on daucus v2_2 (actual rows=N.NN loops=8)
+         ->  Index Scan using vegetables_id_idx_2 on daucus v2_2 (actual rows=N.NN loops=8)
                Index Cond: (id = v1.id)
                Index Searches: 8
                Disabled Nodes: 0

contrib/seg/expected/partition.out

@@ -48,7 +48,7 @@ Partitions: pt12 FOR VALUES IN (1, 2),
 Partition of: pt FOR VALUES IN (1, 2)
 Partition constraint: ((category IS NOT NULL) AND (category = ANY (ARRAY[1, 2])))
 Indexes:
-    "pt12_expr_idx" btree ((mydouble(category) + 1))
-    "pt12_sdata_idx" btree (sdata)
-    "pt12_tdata_idx" btree (tdata COLLATE mycollation)
+    "pti1_1" btree ((mydouble(category) + 1))
+    "pti2_1" btree (sdata)
+    "pti3_1" btree (tdata COLLATE mycollation)
 

src/backend/commands/indexcmds.c

@@ -1366,6 +1366,7 @@ DefineIndex(Oid tableId,
 			{
 				Oid			childRelid = part_oids[i];
 				Relation	childrel;
+				Oid			childNamespace;
 				Oid			child_save_userid;
 				int			child_save_sec_context;
 				int			child_save_nestlevel;
@@ -1375,6 +1376,7 @@ DefineIndex(Oid tableId,
 				bool		found = false;
 
 				childrel = table_open(childRelid, lockmode);
+				childNamespace = RelationGetNamespace(childrel);
 
 				GetUserIdAndSecContext(&child_save_userid,
 									   &child_save_sec_context);
@@ -1506,8 +1508,10 @@ DefineIndex(Oid tableId,
 					 * original IndexStmt might not be.
 					 */
 					childStmt = generateClonedIndexStmt(NULL,
+														childNamespace,
 														parentIndex,
 														attmap,
+														true,
 														NULL);
 
 					/*
@@ -2583,6 +2587,8 @@ makeObjectName(const char *name1, const char *name2, const char *label)
  * name1, name2, and label are used the same way as for makeObjectName(),
  * except that the label can't be NULL; digits will be appended to the label
  * if needed to create a name that is unique within the specified namespace.
+ * If the given label is empty, we only consider names that include at least
+ * one added digit.
  *
  * If isconstraint is true, we also avoid choosing a name matching any
  * existing constraint in the same namespace.  (This is stricter than what
@@ -2616,8 +2622,11 @@ ChooseRelationName(const char *name1, const char *name2,
 	InitDirtySnapshot(SnapshotDirty);
 	pgclassrel = table_open(RelationRelationId, AccessShareLock);
 
-	/* try the unmodified label first */
-	strlcpy(modlabel, label, sizeof(modlabel));
+	/* try the unmodified label first, unless it's empty */
+	if (label[0] != '\0')
+		strlcpy(modlabel, label, sizeof(modlabel));
+	else
+		snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass);
 
 	for (;;)
 	{

src/backend/commands/tablecmds.c

@@ -1295,8 +1295,12 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 										   RelationGetDescr(parent),
 										   false);
 			idxstmt =
-				generateClonedIndexStmt(NULL, idxRel,
-										attmap, &constraintOid);
+				generateClonedIndexStmt(NULL,
+										RelationGetNamespace(rel),
+										idxRel,
+										attmap,
+										true,
+										&constraintOid);
 			DefineIndex(RelationGetRelid(rel),
 						idxstmt,
 						InvalidOid,
@@ -20676,7 +20680,10 @@ AttachPartitionEnsureIndexes(List **wqueue, Relation rel, Relation attachrel)
 			Oid			conOid;
 
 			stmt = generateClonedIndexStmt(NULL,
-										   idxRel, attmap,
+										   RelationGetNamespace(attachrel),
+										   idxRel,
+										   attmap,
+										   true,
 										   &conOid);
 			DefineIndex(RelationGetRelid(attachrel), stmt, InvalidOid,
 						RelationGetRelid(idxRel),

src/backend/parser/parse_utilcmd.c

@@ -1561,10 +1561,18 @@ expandTableLikeClause(RangeVar *heapRel, TableLikeClause *table_like_clause)
 
 			parent_index = index_open(parent_index_oid, AccessShareLock);
 
-			/* Build CREATE INDEX statement to recreate the parent_index */
+			/*
+			 * Build CREATE INDEX statement to recreate the parent_index.  But
+			 * do not clone the parent index's name: that doesn't seem
+			 * entirely appropriate in CREATE TABLE LIKE, and besides there's
+			 * a race condition because we're some ways away from actually
+			 * creating the new index.
+			 */
 			index_stmt = generateClonedIndexStmt(heapRel,
+												 RelationGetNamespace(childrel),
 												 parent_index,
 												 attmap,
+												 false,
 												 NULL);
 
 			/* Copy comment on index, if requested */
@@ -1678,9 +1686,18 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
  * heapRel is stored into the IndexStmt's relation field, but we don't use it
  * otherwise; some callers pass NULL, if they don't need it to be valid.
  * (The target relation might not exist yet, so we mustn't try to access it.)
+ * The namespace OID for the target relation must be provided, though.
  *
  * Attribute numbers in expression Vars are adjusted according to attmap.
  *
+ * If clone_name is true, we copy the source index's name, with addition of
+ * an underscore and digit(s) to make a unique name.  Otherwise we leave it
+ * to DefineIndex to pick a name derived from the target relation's name.
+ * (We typically use "true" for partitioned-index cases and "false" for
+ * CREATE TABLE LIKE.  Note that it's a bit unsafe to use "true" if we're
+ * not immediately going to call DefineIndex, since a conflicting index
+ * could appear in the interim.)
+ *
  * If constraintOid isn't NULL, we store the OID of any constraint associated
  * with the index there.
  *
@@ -1690,8 +1707,11 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
  * complain if that fails to happen).
  */
 IndexStmt *
-generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
+generateClonedIndexStmt(RangeVar *heapRel,
+						Oid heapNamespace,
+						Relation source_idx,
 						const AttrMap *attmap,
+						bool clone_name,
 						Oid *constraintOid)
 {
 	Oid			source_relid = RelationGetRelid(source_idx);
@@ -1768,14 +1788,6 @@ generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
 	index->if_not_exists = false;
 	index->reset_default_tblspc = false;
 
-	/*
-	 * We don't try to preserve the name of the source index; instead, just
-	 * let DefineIndex() choose a reasonable name.  (If we tried to preserve
-	 * the name, we'd get duplicate-relation-name failures unless the source
-	 * table was in a different schema.)
-	 */
-	index->idxname = NULL;
-
 	/*
 	 * If the index is marked PRIMARY or has an exclusion condition, it's
 	 * certainly from a constraint; else, if it's not marked UNIQUE, it
@@ -1854,6 +1866,21 @@ generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
 	else
 		index->isconstraint = false;
 
+	/*
+	 * Choose a name for the new index.  Ideally we'd preserve the name of the
+	 * source index, but that leads to duplicate-relation-name failures if the
+	 * new table is in the same schema.  Instead use ChooseRelationName, which
+	 * will append an underscore and digits as needed to make a unique name.
+	 * Or, if we're told not to choose a name, just set idxname = NULL.
+	 */
+	if (clone_name)
+		index->idxname = ChooseRelationName(RelationGetRelationName(source_idx),
+											NULL, "",
+											heapNamespace,
+											index->isconstraint);
+	else
+		index->idxname = NULL;
+
 	/* Get the index expressions, if any */
 	datum = SysCacheGetAttr(INDEXRELID, ht_idx,
 							Anum_pg_index_indexprs, &isnull);

src/bin/pg_dump/t/002_pg_dump.pl

@@ -4271,7 +4271,7 @@
 
 	'CREATE INDEX ... ON measurement_y2006_m2' => {
 		regexp => qr/^
-		\QCREATE INDEX measurement_y2006m2_city_id_logdate_idx ON dump_test_second_schema.measurement_y2006m2 \E
+		\QCREATE INDEX measurement_city_id_logdate_idx_1 ON dump_test_second_schema.measurement_y2006m2 \E
 		/xm,
 		like => {
 			%full_runs,
@@ -4286,7 +4286,7 @@
 
 	'ALTER INDEX ... ATTACH PARTITION' => {
 		regexp => qr/^
-		\QALTER INDEX dump_test.measurement_city_id_logdate_idx ATTACH PARTITION dump_test_second_schema.measurement_y2006m2_city_id_logdate_idx\E
+		\QALTER INDEX dump_test.measurement_city_id_logdate_idx ATTACH PARTITION dump_test_second_schema.measurement_city_id_logdate_idx_1\E
 		/xm,
 		like => {
 			%full_runs,
@@ -4302,7 +4302,7 @@
 	'ALTER INDEX ... ATTACH PARTITION (primary key)' => {
 		catch_all => 'CREATE ... commands',
 		regexp => qr/^
-		\QALTER INDEX dump_test.measurement_pkey ATTACH PARTITION dump_test_second_schema.measurement_y2006m2_pkey\E
+		\QALTER INDEX dump_test.measurement_pkey ATTACH PARTITION dump_test_second_schema.measurement_pkey_1\E
 		/xm,
 		like => {
 			%full_runs,

src/include/parser/parse_utilcmd.h

@@ -37,8 +37,10 @@ extern PartitionBoundSpec *transformPartitionBound(ParseState *pstate, Relation
 extern List *expandTableLikeClause(RangeVar *heapRel,
 								   TableLikeClause *table_like_clause);
 extern IndexStmt *generateClonedIndexStmt(RangeVar *heapRel,
+										  Oid heapNamespace,
 										  Relation source_idx,
 										  const struct AttrMap *attmap,
+										  bool clone_name,
 										  Oid *constraintOid);
 
 #endif							/* PARSE_UTILCMD_H */

src/test/isolation/expected/partition-drop-index-locking.out

@@ -18,15 +18,15 @@ step s3getlocks:
         WHERE c.relname LIKE 'part_drop_index_locking%'
         ORDER BY s.query, c.relname, l.mode, l.granted;
 
-query                                               |relname                                      |mode               |granted
-----------------------------------------------------+---------------------------------------------+-------------------+-------
-DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking                      |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_idx                  |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_subpart              |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_subpart_child        |AccessExclusiveLock|f      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child        |AccessShareLock    |t      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child_id_idx |AccessShareLock    |t      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child_id_idx1|AccessShareLock    |t      
+query                                               |relname                              |mode               |granted
+----------------------------------------------------+-------------------------------------+-------------------+-------
+DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking              |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_idx          |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_subpart      |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;             |part_drop_index_locking_subpart_child|AccessExclusiveLock|f      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_idx_1_1      |AccessShareLock    |t      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child|AccessShareLock    |t      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_idx_1|AccessShareLock    |t      
 (7 rows)
 
 step s1commit: COMMIT;
@@ -39,14 +39,14 @@ step s3getlocks:
         WHERE c.relname LIKE 'part_drop_index_locking%'
         ORDER BY s.query, c.relname, l.mode, l.granted;
 
-query                                  |relname                                     |mode               |granted
----------------------------------------+--------------------------------------------+-------------------+-------
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking                     |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_idx                 |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart             |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart_child       |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart_child_id_idx|AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart_id_idx      |AccessExclusiveLock|t      
+query                                  |relname                              |mode               |granted
+---------------------------------------+-------------------------------------+-------------------+-------
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking              |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_idx          |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_idx_1        |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_idx_1_1      |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart      |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_idx;|part_drop_index_locking_subpart_child|AccessExclusiveLock|t      
 (6 rows)
 
 step s2commit: COMMIT;
@@ -69,14 +69,14 @@ step s3getlocks:
         WHERE c.relname LIKE 'part_drop_index_locking%'
         ORDER BY s.query, c.relname, l.mode, l.granted;
 
-query                                               |relname                                      |mode               |granted
-----------------------------------------------------+---------------------------------------------+-------------------+-------
-DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart              |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart_child        |AccessExclusiveLock|f      
-DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart_idx          |AccessExclusiveLock|t      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child        |AccessShareLock    |t      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child_id_idx |AccessShareLock    |t      
-SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child_id_idx1|AccessShareLock    |t      
+query                                               |relname                              |mode               |granted
+----------------------------------------------------+-------------------------------------+-------------------+-------
+DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart      |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart_child|AccessExclusiveLock|f      
+DROP INDEX part_drop_index_locking_subpart_idx;     |part_drop_index_locking_subpart_idx  |AccessExclusiveLock|t      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_idx_1_1      |AccessShareLock    |t      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_child|AccessShareLock    |t      
+SELECT * FROM part_drop_index_locking_subpart_child;|part_drop_index_locking_subpart_idx_1|AccessShareLock    |t      
 (6 rows)
 
 step s1commit: COMMIT;
@@ -89,12 +89,12 @@ step s3getlocks:
         WHERE c.relname LIKE 'part_drop_index_locking%'
         ORDER BY s.query, c.relname, l.mode, l.granted;
 
-query                                          |relname                                      |mode               |granted
------------------------------------------------+---------------------------------------------+-------------------+-------
-DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart              |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_child        |AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_child_id_idx1|AccessExclusiveLock|t      
-DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_idx          |AccessExclusiveLock|t      
+query                                          |relname                              |mode               |granted
+-----------------------------------------------+-------------------------------------+-------------------+-------
+DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart      |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_child|AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_idx  |AccessExclusiveLock|t      
+DROP INDEX part_drop_index_locking_subpart_idx;|part_drop_index_locking_subpart_idx_1|AccessExclusiveLock|t      
 (4 rows)
 
 step s2commit: COMMIT;