[Justin Pryzby <pryzby@telsasoft.com>]

Forking this thread, since the existing CFs have been closed.
https://www.postgresql.org/message-id/flat/20200914143102.GX18552%40telsasoft.com#58b1056488451f8594...

The strategy is to create catalog entries for all tables with indisvalid=false,
and then process them like REINDEX CONCURRENTLY.  If it's interrupted, it
leaves INVALID indexes, which can be cleaned up with DROP or REINDEX, same as
CIC on a plain table.

On Sat, Aug 08, 2020 at 01:37:44AM -0500, Justin Pryzby wrote:
> On Mon, Jun 15, 2020 at 09:37:42PM +0900, Michael Paquier wrote:
> > On Mon, Jun 15, 2020 at 08:15:05PM +0800, 李杰(慎追) wrote:
> > > As shown above, an error occurred while creating an index in the second partition. 
> > > It can be clearly seen that the index of the partitioned table is invalid 
> > > and the index of the first partition is normal, the second partition is invalid, 
> > > and the Third Partition index does not exist at all.
> > 
> > That's a problem.  I really think that we should make the steps of the
> > concurrent operation consistent across all relations, meaning that all
> > the indexes should be created as invalid for all the parts of the
> > partition tree, including partitioned tables as well as their
> > partitions, in the same transaction.  Then a second new transaction
> > gets used for the index build, followed by a third one for the
> > validation that switches the indexes to become valid.
> 
> Note that the mentioned problem wasn't serious: there was missing index on
> child table, therefor the parent index was invalid, as intended.  However I
> agree that it's not nice that the command can fail so easily and leave behind
> some indexes created successfully and some failed some not created at all.
> 
> But I took your advice initially creating invalid inds.
...
> That gave me the idea to layer CIC on top of Reindex, since I think it does
> exactly what's needed.

On Sat, Sep 26, 2020 at 02:56:55PM -0500, Justin Pryzby wrote:
> On Thu, Sep 24, 2020 at 05:11:03PM +0900, Michael Paquier wrote:
> > It would be good also to check if
> > we have a partition index tree that maps partially with a partition
> > table tree (aka no all table partitions have a partition index), where
> > these don't get clustered because there is no index to work on.
> 
> This should not happen, since a incomplete partitioned index is "invalid".

-- 
Justin

Attachments:

  [text/x-diff] v10-0001-Allow-CREATE-INDEX-CONCURRENTLY-on-partitioned-t.patch (14.1K, ../20201031063117.GF3080@telsasoft.com/2-v10-0001-Allow-CREATE-INDEX-CONCURRENTLY-on-partitioned-t.patch)
  download | inline diff:
From 9f146ace80596f0177163de34556d8ef581fd2e3 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Sat, 6 Jun 2020 17:42:23 -0500
Subject: [PATCH v10 1/3] Allow CREATE INDEX CONCURRENTLY on partitioned table

Note, this effectively reverts 050098b14, so take care to not reintroduce the
bug it fixed.

XXX: does pgstat_progress_update_param() break other commands progress ?
---
 doc/src/sgml/ref/create_index.sgml     |   9 --
 src/backend/commands/indexcmds.c       | 141 ++++++++++++++++++-------
 src/test/regress/expected/indexing.out |  60 ++++++++++-
 src/test/regress/sql/indexing.sql      |  18 +++-
 4 files changed, 172 insertions(+), 56 deletions(-)

diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index 749db2845e..ba4424d379 100644
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -661,15 +661,6 @@ Indexes:
     cannot.
    </para>
 
-   <para>
-    Concurrent builds for indexes on partitioned tables are currently not
-    supported.  However, you may concurrently build the index on each
-    partition individually and then finally create the partitioned index
-    non-concurrently in order to reduce the time where writes to the
-    partitioned table will be locked out.  In this case, building the
-    partitioned index is a metadata only operation.
-   </para>
-
   </refsect2>
  </refsect1>
 
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 996f1ed070..c1dd4c8362 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -93,6 +93,7 @@ static bool ReindexRelationConcurrently(Oid relationOid, int options);
 
 static void ReindexPartitions(Oid relid, int options, bool isTopLevel);
 static void ReindexMultipleInternal(List *relids, int options);
+static void reindex_invalid_child_indexes(Oid indexRelationId);
 static void reindex_error_callback(void *args);
 static void update_relispartition(Oid relationId, bool newval);
 static bool CompareOpclassOptions(Datum *opts1, Datum *opts2, int natts);
@@ -667,17 +668,6 @@ DefineIndex(Oid relationId,
 	partitioned = rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE;
 	if (partitioned)
 	{
-		/*
-		 * Note: we check 'stmt->concurrent' rather than 'concurrent', so that
-		 * the error is thrown also for temporary tables.  Seems better to be
-		 * consistent, even though we could do it on temporary table because
-		 * we're not actually doing it concurrently.
-		 */
-		if (stmt->concurrent)
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot create index on partitioned table \"%s\" concurrently",
-							RelationGetRelationName(rel))));
 		if (stmt->excludeOpNames)
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -1111,6 +1101,11 @@ DefineIndex(Oid relationId,
 		if (pd->nparts != 0)
 			flags |= INDEX_CREATE_INVALID;
 	}
+	else if (concurrent && OidIsValid(parentIndexId))
+	{
+		/* If concurrent, initially build index partitions as "invalid" */
+		flags |= INDEX_CREATE_INVALID;
+	}
 
 	if (stmt->deferrable)
 		constr_flags |= INDEX_CONSTR_CREATE_DEFERRABLE;
@@ -1163,6 +1158,14 @@ DefineIndex(Oid relationId,
 		 */
 		if (!stmt->relation || stmt->relation->inh)
 		{
+			/*
+			 * Need to close the relation before recursing into children, so
+			 * copy needed data into a longlived context.
+			 */
+
+			MemoryContext	ind_context = AllocSetContextCreate(PortalContext, "CREATE INDEX",
+					ALLOCSET_DEFAULT_SIZES);
+			MemoryContext	oldcontext = MemoryContextSwitchTo(ind_context);
 			PartitionDesc partdesc = RelationGetPartitionDesc(rel);
 			int			nparts = partdesc->nparts;
 			Oid		   *part_oids = palloc(sizeof(Oid) * nparts);
@@ -1170,12 +1173,15 @@ DefineIndex(Oid relationId,
 			TupleDesc	parentDesc;
 			Oid		   *opfamOids;
 
+			// If concurrent, maybe this should be done after excluding indexes which already exist ?
 			pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_TOTAL,
 										 nparts);
 
 			memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
+			parentDesc = CreateTupleDescCopy(RelationGetDescr(rel));
+			table_close(rel, NoLock);
+			MemoryContextSwitchTo(oldcontext);
 
-			parentDesc = RelationGetDescr(rel);
 			opfamOids = palloc(sizeof(Oid) * numberOfKeyAttributes);
 			for (i = 0; i < numberOfKeyAttributes; i++)
 				opfamOids[i] = get_opclass_family(classObjectId[i]);
@@ -1218,10 +1224,12 @@ DefineIndex(Oid relationId,
 					continue;
 				}
 
+				oldcontext = MemoryContextSwitchTo(ind_context);
 				childidxs = RelationGetIndexList(childrel);
 				attmap =
 					build_attrmap_by_name(RelationGetDescr(childrel),
 										  parentDesc);
+				MemoryContextSwitchTo(oldcontext);
 
 				foreach(cell, childidxs)
 				{
@@ -1292,10 +1300,14 @@ DefineIndex(Oid relationId,
 				 */
 				if (!found)
 				{
-					IndexStmt  *childStmt = copyObject(stmt);
+					IndexStmt  *childStmt;
 					bool		found_whole_row;
 					ListCell   *lc;
 
+					oldcontext = MemoryContextSwitchTo(ind_context);
+					childStmt = copyObject(stmt);
+					MemoryContextSwitchTo(oldcontext);
+
 					/*
 					 * We can't use the same index name for the child index,
 					 * so clear idxname to let the recursive invocation choose
@@ -1347,10 +1359,18 @@ DefineIndex(Oid relationId,
 								createdConstraintId,
 								is_alter_table, check_rights, check_not_in_use,
 								skip_build, quiet);
+					if (concurrent)
+					{
+						PopActiveSnapshot();
+						PushActiveSnapshot(GetTransactionSnapshot());
+						invalidate_parent = true;
+					}
 				}
 
-				pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
-											 i + 1);
+				/* For concurrent build, this is a catalog-only stage */
+				if (!concurrent)
+					pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
+												 i + 1);
 				free_attrmap(attmap);
 			}
 
@@ -1360,51 +1380,42 @@ DefineIndex(Oid relationId,
 			 * invalid, this is incorrect, so update our row to invalid too.
 			 */
 			if (invalidate_parent)
-			{
-				Relation	pg_index = table_open(IndexRelationId, RowExclusiveLock);
-				HeapTuple	tup,
-							newtup;
-
-				tup = SearchSysCache1(INDEXRELID,
-									  ObjectIdGetDatum(indexRelationId));
-				if (!HeapTupleIsValid(tup))
-					elog(ERROR, "cache lookup failed for index %u",
-						 indexRelationId);
-				newtup = heap_copytuple(tup);
-				((Form_pg_index) GETSTRUCT(newtup))->indisvalid = false;
-				CatalogTupleUpdate(pg_index, &tup->t_self, newtup);
-				ReleaseSysCache(tup);
-				table_close(pg_index, RowExclusiveLock);
-				heap_freetuple(newtup);
-			}
-		}
+				index_set_state_flags(indexRelationId, INDEX_DROP_CLEAR_VALID);
+		} else
+			table_close(rel, NoLock);
 
 		/*
 		 * Indexes on partitioned tables are not themselves built, so we're
 		 * done here.
 		 */
-		table_close(rel, NoLock);
 		if (!OidIsValid(parentIndexId))
+		{
+			if (concurrent)
+				reindex_invalid_child_indexes(indexRelationId);
+
 			pgstat_progress_end_command();
+		}
+
 		return address;
 	}
 
-	if (!concurrent)
+	table_close(rel, NoLock);
+	if (!concurrent || OidIsValid(parentIndexId))
 	{
-		/* Close the heap and we're done, in the non-concurrent case */
-		table_close(rel, NoLock);
+		/*
+		 * We're done if this is the top-level index,
+		 * or the catalog-only phase of a partition built concurrently
+		 */
 
-		/* If this is the top-level index, we're done. */
 		if (!OidIsValid(parentIndexId))
 			pgstat_progress_end_command();
 
 		return address;
 	}
 
-	/* save lockrelid and locktag for below, then close rel */
+	/* save lockrelid and locktag for below */
 	heaprelid = rel->rd_lockInfo.lockRelId;
 	SET_LOCKTAG_RELATION(heaplocktag, heaprelid.dbId, heaprelid.relId);
-	table_close(rel, NoLock);
 
 	/*
 	 * For a concurrent build, it's important to make the catalog entries
@@ -1586,6 +1597,56 @@ DefineIndex(Oid relationId,
 	return address;
 }
 
+/* Reindex invalid child indexes created earlier */
+static void
+reindex_invalid_child_indexes(Oid indexRelationId)
+{
+	ListCell *lc;
+	int		npart = 0;
+
+	MemoryContext	ind_context = AllocSetContextCreate(PortalContext, "CREATE INDEX",
+			ALLOCSET_DEFAULT_SIZES);
+	MemoryContext	oldcontext;
+	List		*childs = find_inheritance_children(indexRelationId, ShareLock);
+	List		*partitions = NIL;
+
+	PreventInTransactionBlock(true, "REINDEX INDEX");
+
+	foreach (lc, childs)
+	{
+		Oid			partoid = lfirst_oid(lc);
+
+		pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
+									 npart++);
+
+		if (get_index_isvalid(partoid) ||
+				!RELKIND_HAS_STORAGE(get_rel_relkind(partoid)))
+			continue;
+
+		/* Save partition OID */
+		oldcontext = MemoryContextSwitchTo(ind_context);
+		partitions = lappend_oid(partitions, partoid);
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	/*
+	 * Process each partition listed in a separate transaction.  Note that
+	 * this commits and then starts a new transaction immediately.
+	 */
+	ReindexMultipleInternal(partitions, REINDEXOPT_CONCURRENTLY);
+
+	/*
+	 * CIC needs to mark a partitioned index as VALID, which itself
+	 * requires setting READY, which is unset for CIC (even though
+	 * it's meaningless for an index without storage).
+	 * This must be done only while holding a lock which precludes adding
+	 * partitions.
+	 * See also: validatePartitionedIndex().
+	 */
+	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_READY);
+	CommandCounterIncrement();
+	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID);
+}
 
 /*
  * CheckMutability
diff --git a/src/test/regress/expected/indexing.out b/src/test/regress/expected/indexing.out
index 49b6f7c18f..2fb00a2fa7 100644
--- a/src/test/regress/expected/indexing.out
+++ b/src/test/regress/expected/indexing.out
@@ -50,11 +50,63 @@ select relname, relkind, relhassubclass, inhparent::regclass
 (8 rows)
 
 drop table idxpart;
--- Some unsupported features
+-- CIC on partitioned table
 create table idxpart (a int, b int, c text) partition by range (a);
-create table idxpart1 partition of idxpart for values from (0) to (10);
-create index concurrently on idxpart (a);
-ERROR:  cannot create index on partitioned table "idxpart" concurrently
+create table idxpart1 partition of idxpart for values from (0) to (10) partition by range(a);
+create table idxpart11 partition of idxpart1 for values from (0) to (10) partition by range(a);
+create table idxpart111 partition of idxpart11 default partition by range(a);
+create table idxpart1111 partition of idxpart111 default partition by range(a);
+create table idxpart2 partition of idxpart for values from (10) to (20);
+insert into idxpart2 values(10),(10); -- not unique
+create index concurrently on idxpart (a); -- partitioned
+create index concurrently on idxpart1 (a); -- partitioned and partition
+create index concurrently on idxpart11 (a); -- partitioned and partition, with no leaves
+create index concurrently on idxpart2 (a); -- leaf
+create unique index concurrently on idxpart (a); -- partitioned, unique failure
+ERROR:  could not create unique index "idxpart2_a_idx2_ccnew"
+DETAIL:  Key (a)=(10) is duplicated.
+\d idxpart
+        Partitioned table "public.idxpart"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+ b      | integer |           |          | 
+ c      | text    |           |          | 
+Partition key: RANGE (a)
+Indexes:
+    "idxpart_a_idx" btree (a)
+    "idxpart_a_idx1" UNIQUE, btree (a) INVALID
+Number of partitions: 2 (Use \d+ to list them.)
+
+\d idxpart1
+        Partitioned table "public.idxpart1"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+ b      | integer |           |          | 
+ c      | text    |           |          | 
+Partition of: idxpart FOR VALUES FROM (0) TO (10)
+Partition key: RANGE (a)
+Indexes:
+    "idxpart1_a_idx" btree (a) INVALID
+    "idxpart1_a_idx1" btree (a)
+    "idxpart1_a_idx2" UNIQUE, btree (a) INVALID
+Number of partitions: 1 (Use \d+ to list them.)
+
+\d idxpart2
+              Table "public.idxpart2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           |          | 
+ b      | integer |           |          | 
+ c      | text    |           |          | 
+Partition of: idxpart FOR VALUES FROM (10) TO (20)
+Indexes:
+    "idxpart2_a_idx" btree (a)
+    "idxpart2_a_idx1" btree (a)
+    "idxpart2_a_idx2" UNIQUE, btree (a) INVALID
+    "idxpart2_a_idx2_ccnew" UNIQUE, btree (a) INVALID
+
 drop table idxpart;
 -- Verify bugfix with query on indexed partitioned table with no partitions
 -- https://postgr.es/m/20180124162006.pmapfiznhgngwtjf@alvherre.pgsql
diff --git a/src/test/regress/sql/indexing.sql b/src/test/regress/sql/indexing.sql
index fc1479dca6..610c12de9e 100644
--- a/src/test/regress/sql/indexing.sql
+++ b/src/test/regress/sql/indexing.sql
@@ -29,10 +29,22 @@ select relname, relkind, relhassubclass, inhparent::regclass
 	where relname like 'idxpart%' order by relname;
 drop table idxpart;
 
--- Some unsupported features
+-- CIC on partitioned table
 create table idxpart (a int, b int, c text) partition by range (a);
-create table idxpart1 partition of idxpart for values from (0) to (10);
-create index concurrently on idxpart (a);
+create table idxpart1 partition of idxpart for values from (0) to (10) partition by range(a);
+create table idxpart11 partition of idxpart1 for values from (0) to (10) partition by range(a);
+create table idxpart111 partition of idxpart11 default partition by range(a);
+create table idxpart1111 partition of idxpart111 default partition by range(a);
+create table idxpart2 partition of idxpart for values from (10) to (20);
+insert into idxpart2 values(10),(10); -- not unique
+create index concurrently on idxpart (a); -- partitioned
+create index concurrently on idxpart1 (a); -- partitioned and partition
+create index concurrently on idxpart11 (a); -- partitioned and partition, with no leaves
+create index concurrently on idxpart2 (a); -- leaf
+create unique index concurrently on idxpart (a); -- partitioned, unique failure
+\d idxpart
+\d idxpart1
+\d idxpart2
 drop table idxpart;
 
 -- Verify bugfix with query on indexed partitioned table with no partitions
-- 
2.17.0

  [text/x-diff] v10-0002-Add-SKIPVALID-flag-for-more-integration.patch (3.8K, ../20201031063117.GF3080@telsasoft.com/3-v10-0002-Add-SKIPVALID-flag-for-more-integration.patch)
  download | inline diff:
From dad382a194d5c7c82204fb011f1fd08507d20d8b Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Fri, 30 Oct 2020 16:23:02 -0500
Subject: [PATCH v10 2/3] Add SKIPVALID flag for more integration

---
 src/backend/commands/indexcmds.c | 54 +++++++++++---------------------
 src/include/nodes/parsenodes.h   |  7 +++--
 2 files changed, 22 insertions(+), 39 deletions(-)

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index c1dd4c8362..f4d49f5bf6 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1597,53 +1597,30 @@ DefineIndex(Oid relationId,
 	return address;
 }
 
-/* Reindex invalid child indexes created earlier */
+/*
+ * Reindex invalid child indexes created earlier thereby validating
+ * the parent index.
+ */
 static void
 reindex_invalid_child_indexes(Oid indexRelationId)
 {
-	ListCell *lc;
-	int		npart = 0;
-
-	MemoryContext	ind_context = AllocSetContextCreate(PortalContext, "CREATE INDEX",
-			ALLOCSET_DEFAULT_SIZES);
-	MemoryContext	oldcontext;
-	List		*childs = find_inheritance_children(indexRelationId, ShareLock);
-	List		*partitions = NIL;
-
-	PreventInTransactionBlock(true, "REINDEX INDEX");
-
-	foreach (lc, childs)
-	{
-		Oid			partoid = lfirst_oid(lc);
-
-		pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_DONE,
-									 npart++);
-
-		if (get_index_isvalid(partoid) ||
-				!RELKIND_HAS_STORAGE(get_rel_relkind(partoid)))
-			continue;
-
-		/* Save partition OID */
-		oldcontext = MemoryContextSwitchTo(ind_context);
-		partitions = lappend_oid(partitions, partoid);
-		MemoryContextSwitchTo(oldcontext);
-	}
-
-	/*
-	 * Process each partition listed in a separate transaction.  Note that
-	 * this commits and then starts a new transaction immediately.
-	 */
-	ReindexMultipleInternal(partitions, REINDEXOPT_CONCURRENTLY);
-
 	/*
 	 * CIC needs to mark a partitioned index as VALID, which itself
 	 * requires setting READY, which is unset for CIC (even though
 	 * it's meaningless for an index without storage).
 	 * This must be done only while holding a lock which precludes adding
 	 * partitions.
-	 * See also: validatePartitionedIndex().
 	 */
+	CommandCounterIncrement();
 	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_READY);
+
+	/*
+	 * Process each partition listed in a separate transaction.  Note that
+	 * this commits and then starts a new transaction immediately.
+	 */
+	ReindexPartitions(indexRelationId,
+			REINDEXOPT_CONCURRENTLY | REINDEXOPT_SKIPVALID, true);
+
 	CommandCounterIncrement();
 	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID);
 }
@@ -2927,6 +2904,11 @@ ReindexPartitions(Oid relid, int options, bool isTopLevel)
 		if (!RELKIND_HAS_STORAGE(partkind))
 			continue;
 
+		/* Skip invalid indexes, if requested */
+		if ((options & REINDEXOPT_SKIPVALID) != 0 &&
+				get_index_isvalid(partoid))
+			continue;
+
 		Assert(partkind == RELKIND_INDEX ||
 			   partkind == RELKIND_RELATION);
 
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 93fd796163..d099378951 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -3356,10 +3356,11 @@ typedef struct ConstraintsSetStmt
  */
 
 /* Reindex options */
-#define REINDEXOPT_VERBOSE (1 << 0) /* print progress info */
+#define REINDEXOPT_VERBOSE	(1 << 0) /* print progress info */
 #define REINDEXOPT_REPORT_PROGRESS (1 << 1) /* report pgstat progress */
-#define REINDEXOPT_MISSING_OK (1 << 2)	/* skip missing relations */
-#define REINDEXOPT_CONCURRENTLY (1 << 3)	/* concurrent mode */
+#define REINDEXOPT_MISSING_OK	(1 << 2)	/* skip missing relations */
+#define REINDEXOPT_CONCURRENTLY	(1 << 3)	/* concurrent mode */
+#define REINDEXOPT_SKIPVALID	(1 << 4)	/* skip valid indexes */
 
 typedef enum ReindexObjectType
 {
-- 
2.17.0

  [text/x-diff] v10-0003-ReindexPartitions-to-set-indisvalid.patch (2.4K, ../20201031063117.GF3080@telsasoft.com/4-v10-0003-ReindexPartitions-to-set-indisvalid.patch)
  download | inline diff:
From 2335546e703996d1f4fdf7a9f3c5a930f74d4bb7 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Fri, 30 Oct 2020 23:52:31 -0500
Subject: [PATCH v10 3/3] ReindexPartitions() to set indisvalid..

Something like this should probably have been included in
a6642b3ae060976b42830b7dc8f29ec190ab05e4

See also 71a05b223, which mentioned the absence of any way to validate an
index.
---
 src/backend/commands/indexcmds.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index f4d49f5bf6..77390f0c1e 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1608,8 +1608,6 @@ reindex_invalid_child_indexes(Oid indexRelationId)
 	 * CIC needs to mark a partitioned index as VALID, which itself
 	 * requires setting READY, which is unset for CIC (even though
 	 * it's meaningless for an index without storage).
-	 * This must be done only while holding a lock which precludes adding
-	 * partitions.
 	 */
 	CommandCounterIncrement();
 	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_READY);
@@ -1620,9 +1618,6 @@ reindex_invalid_child_indexes(Oid indexRelationId)
 	 */
 	ReindexPartitions(indexRelationId,
 			REINDEXOPT_CONCURRENTLY | REINDEXOPT_SKIPVALID, true);
-
-	CommandCounterIncrement();
-	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID);
 }
 
 /*
@@ -2924,6 +2919,24 @@ ReindexPartitions(Oid relid, int options, bool isTopLevel)
 	 */
 	ReindexMultipleInternal(partitions, options);
 
+	/*
+	 * If indexes exist on all of the partitioned table's children, and we
+	 * just reindexed them, then we know they're valid, and so can mark the
+	 * parent index as valid.
+	 * This handles the case of CREATE INDEX CONCURRENTLY.
+	 * See also: validatePartitionedIndex().
+	 */
+	if (get_rel_relkind(relid) == RELKIND_PARTITIONED_INDEX
+			&& !get_index_isvalid(relid))
+	{
+		Oid	tableoid = IndexGetRelation(relid, false);
+		List	*child_tables = find_all_inheritors(tableoid, ShareLock, NULL);
+
+		/* Both lists include their parent relation as well as any intermediate partitioned rels */
+		if (list_length(inhoids) == list_length(child_tables))
+			index_set_state_flags(relid, INDEX_CREATE_SET_VALID);
+	}
+
 	/*
 	 * Clean up working storage --- note we must do this after
 	 * StartTransactionCommand, else we might be trying to delete the active
-- 
2.17.0