Subject: [PATCH v14 4/7] Track collation versions for indexes.

From: Thomas Munro <[email-masked]>
Date: Tue, 28 May 2019 14:16:29 -0400

Record the current version of dependent collations in pg_depend when creating
or rebuilding an index.  The version is checked against the current version
whenever we call get_relation_info for an index or open the parent table
during non-full VACUUM or ANALYZE.  Warn that the index may be corrupted if
the versions don't match.

A new flag is added in RelationData to specify that the check has already been
done to avoid repetition.

Thanks to Doug Doole, Peter Eisentraut, Christoph Berg, Laurenz Albe,
Michael Paquier, Robert Haas, Tom Lane and others for design discussion.

Author: Thomas Munro and Julien Rouhaud
Reviewed-by: Peter Eisentraut, Laurenz Albe
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
---
 doc/src/sgml/func.sgml                        |   2 +-
 doc/src/sgml/ref/reindex.sgml                 |   6 +
 src/backend/catalog/dependency.c              | 189 +++++++++++++++--
 src/backend/catalog/heap.c                    |   7 +-
 src/backend/catalog/index.c                   | 191 +++++++++++++++++-
 src/backend/catalog/pg_constraint.c           |   2 +-
 src/backend/catalog/pg_depend.c               | 136 +++++++++++--
 src/backend/catalog/pg_type.c                 |  69 +++++++
 src/backend/commands/collationcmds.c          |  22 +-
 src/backend/commands/vacuum.c                 |  31 +++
 src/backend/optimizer/util/plancat.c          |   9 +
 src/backend/utils/adt/pg_locale.c             |  52 ++++-
 src/backend/utils/cache/relcache.c            |   2 +
 src/include/catalog/dependency.h              |  22 +-
 src/include/catalog/index.h                   |   2 +
 src/include/catalog/pg_type.h                 |   2 +
 src/include/utils/pg_locale.h                 |   2 +-
 src/include/utils/rel.h                       |   1 +
 src/test/Makefile                             |   5 +-
 src/test/locale/.gitignore                    |   1 +
 src/test/locale/Makefile                      |   7 +
 src/test/locale/t/001_index.pl                |  76 +++++++
 .../regress/expected/collate.icu.utf8.out     | 130 ++++++++++++
 src/test/regress/expected/create_index.out    |   8 +-
 src/test/regress/sql/collate.icu.utf8.sql     |  83 ++++++++
 25 files changed, 974 insertions(+), 83 deletions(-)
 create mode 100644 src/test/locale/t/001_index.pl

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b2d991ac7f..8414f2bfd9 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -21115,7 +21115,7 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
    <para>
     <function>pg_collation_actual_version</function> returns the actual
     version of the collation object as it is currently installed in the
-    operating system.
+    operating system.  An empty string is returned if the version is unknown.
    </para>
 
    <para>
diff --git a/doc/src/sgml/ref/reindex.sgml b/doc/src/sgml/ref/reindex.sgml
index c54a7c420d..7209a606fa 100644
--- a/doc/src/sgml/ref/reindex.sgml
+++ b/doc/src/sgml/ref/reindex.sgml
@@ -39,6 +39,12 @@ REINDEX [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] { IN
 
    <itemizedlist>
     <listitem>
+     <para>
+      The index depends on the sort order of a collation, and the definition
+      of the collation has changed.  This can cause an index to fail to
+      find a key that is present in the index.  On some systems, collation
+      versions are tracked in order to generate warnings when this happens.
+     </para>
      <para>
       An index has become corrupted, and no longer contains valid
       data. Although in theory this should never happen, in
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 660033b9c1..c0e36ef4cd 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -78,6 +78,7 @@
 #include "rewrite/rewriteRemove.h"
 #include "storage/lmgr.h"
 #include "utils/acl.h"
+#include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/lsyscache.h"
@@ -138,6 +139,9 @@ typedef struct
 {
 	ObjectAddresses *addrs;		/* addresses being accumulated */
 	List	   *rtables;		/* list of rangetables to resolve Vars */
+	bool		track_version;	/* whether caller asked to track dependency
+								 * versions */
+	NodeTag		type;			/* nodetag of the current node */
 } find_expr_references_context;
 
 /*
@@ -438,6 +442,80 @@ performMultipleDeletions(const ObjectAddresses *objects,
 	table_close(depRel, RowExclusiveLock);
 }
 
+/*
+ * Call a function for all objects that depend on 'object'.  If the function
+ * returns a non-NULL pointer to a new version string, update the version.
+ */
+void
+visitDependentObjects(const ObjectAddress *object,
+					  VisitDependentObjectsFun callback,
+					  void *userdata)
+{
+	Relation	depRel;
+	ScanKeyData key[3];
+	SysScanDesc scan;
+	HeapTuple	tup;
+	ObjectAddress otherObject;
+
+	ScanKeyInit(&key[0],
+				Anum_pg_depend_classid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(object->classId));
+	ScanKeyInit(&key[1],
+				Anum_pg_depend_objid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(object->objectId));
+	ScanKeyInit(&key[2],
+				Anum_pg_depend_objsubid,
+				BTEqualStrategyNumber, F_INT4EQ,
+				Int32GetDatum(object->objectSubId));
+
+	depRel = table_open(DependRelationId, RowExclusiveLock);
+	scan = systable_beginscan(depRel, DependDependerIndexId, true,
+							  NULL, 3, key);
+
+	while (HeapTupleIsValid(tup = systable_getnext(scan)))
+	{
+		Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
+		char *cur_version, *new_version;
+		Datum depversion;
+		bool isnull;
+
+		otherObject.classId = foundDep->refclassid;
+		otherObject.objectId = foundDep->refobjid;
+		otherObject.objectSubId = foundDep->refobjsubid;
+
+		depversion = heap_getattr(tup, Anum_pg_depend_refobjversion,
+								  RelationGetDescr(depRel), &isnull);
+
+		cur_version = isnull ? NULL : TextDatumGetCString(depversion);
+
+		new_version = callback(&otherObject, cur_version, userdata);
+		if (new_version)
+		{
+			Datum	values[Natts_pg_depend];
+			bool	nulls[Natts_pg_depend];
+			bool	replaces[Natts_pg_depend];
+
+			memset(values, 0, sizeof(values));
+			memset(nulls, false, sizeof(nulls));
+			memset(replaces, false, sizeof(replaces));
+
+			values[Anum_pg_depend_refobjversion - 1] =
+				CStringGetTextDatum(new_version);
+			replaces[Anum_pg_depend_refobjversion - 1] = true;
+
+			tup = heap_modify_tuple(tup, RelationGetDescr(depRel), values,
+									nulls, replaces);
+			CatalogTupleUpdate(depRel, &tup->t_self, tup);
+
+			heap_freetuple(tup);
+		}
+	}
+	systable_endscan(scan);
+	table_close(depRel, RowExclusiveLock);
+}
+
 /*
  * findDependentObjects - find all objects that depend on 'object'
  *
@@ -1591,6 +1669,10 @@ recordDependencyOnExpr(const ObjectAddress *depender,
 	find_expr_references_context context;
 
 	context.addrs = new_object_addresses();
+	if (expr)
+		context.type = expr->type;
+	else
+		context.type = T_Invalid;
 
 	/* Set up interpretation for Vars at varlevelsup = 0 */
 	context.rtables = list_make1(rtable);
@@ -1603,9 +1685,10 @@ recordDependencyOnExpr(const ObjectAddress *depender,
 
 	/* And record 'em */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs, NULL,
+							   context.addrs->refs,
 							   context.addrs->numrefs,
-							   behavior);
+							   behavior,
+							   false);
 
 	free_object_addresses(context.addrs);
 }
@@ -1632,12 +1715,18 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 								Node *expr, Oid relId,
 								DependencyType behavior,
 								DependencyType self_behavior,
-								bool reverse_self)
+								bool reverse_self,
+								bool track_version)
 {
 	find_expr_references_context context;
 	RangeTblEntry rte;
 
 	context.addrs = new_object_addresses();
+	context.track_version = track_version;
+	if (expr)
+		context.type = expr->type;
+	else
+		context.type = T_Invalid;
 
 	/* We gin up a rather bogus rangetable list to handle Vars */
 	MemSet(&rte, 0, sizeof(rte));
@@ -1691,9 +1780,10 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 		/* Record the self-dependencies with the appropriate direction */
 		if (!reverse_self)
 			recordMultipleDependencies(depender,
-									   self_addrs->refs, NULL,
+									   self_addrs->refs,
 									   self_addrs->numrefs,
-									   self_behavior);
+									   self_behavior,
+									   track_version);
 		else
 		{
 			/* Can't use recordMultipleDependencies, so do it the hard way */
@@ -1712,9 +1802,10 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 
 	/* Record the external dependencies */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs, NULL,
+							   context.addrs->refs,
 							   context.addrs->numrefs,
-							   behavior);
+							   behavior,
+							   track_version);
 
 	free_object_addresses(context.addrs);
 }
@@ -1736,8 +1827,13 @@ static bool
 find_expr_references_walker(Node *node,
 							find_expr_references_context *context)
 {
+	NodeTag parent_type = context->type;
+
 	if (node == NULL)
 		return false;
+
+	context->type = node->type;
+
 	if (IsA(node, Var))
 	{
 		Var		   *var = (Var *) node;
@@ -1770,6 +1866,46 @@ find_expr_references_walker(Node *node,
 			/* If it's a plain relation, reference this column */
 			add_object_address(OCLASS_CLASS, rte->relid, var->varattno,
 							   context->addrs);
+
+			/* Record collations from the type itself, or underlying in case of
+			 * complex type.  Note that if the direct parent is a CollateExpr
+			 * node, there's no need to record the type underlying collation if
+			 * any.  A dependency already exists for the owning relation, and a
+			 * change in the collation sort order wouldn't cause any harm as
+			 * the collation isn't used at all in such case.
+			 */
+			if (parent_type != T_CollateExpr)
+			{
+				/* type's collation if valid */
+				if (OidIsValid(var->varcollid))
+				{
+					add_object_address(OCLASS_COLLATION, var->varcollid, 0,
+									   context->addrs);
+				}
+				/*
+				 * otherwise, it may be a composite type having underlying
+				 * collations */
+				else if (var->vartype >= FirstNormalObjectId)
+				{
+					List	   *collations = NIL;
+					ListCell   *lc;
+
+					collations = GetTypeCollations(var->vartype, false);
+
+					foreach(lc, collations)
+					{
+						Oid coll = lfirst_oid(lc);
+
+						if (OidIsValid(coll) &&
+							(coll != DEFAULT_COLLATION_OID ||
+							 context->track_version)
+						)
+							add_object_address(OCLASS_COLLATION,
+									lfirst_oid(lc), 0,
+									context->addrs);
+					}
+				}
+			}
 		}
 
 		/*
@@ -1794,11 +1930,13 @@ find_expr_references_walker(Node *node,
 		/*
 		 * We must also depend on the constant's collation: it could be
 		 * different from the datatype's, if a CollateExpr was const-folded to
-		 * a simple constant.  However we can save work in the most common
-		 * case where the collation is "default", since we know that's pinned.
+		 * a simple constant.  However we can save work in the most common case
+		 * where the collation is "default", since we know that's pinned, if
+		 * the caller didn't ask to track dependency versions.
 		 */
 		if (OidIsValid(con->constcollid) &&
-			con->constcollid != DEFAULT_COLLATION_OID)
+				(con->constcollid != DEFAULT_COLLATION_OID ||
+					context->track_version))
 			add_object_address(OCLASS_COLLATION, con->constcollid, 0,
 							   context->addrs);
 
@@ -1888,7 +2026,8 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* and its collation, just as for Consts */
 		if (OidIsValid(param->paramcollid) &&
-			param->paramcollid != DEFAULT_COLLATION_OID)
+				(param->paramcollid != DEFAULT_COLLATION_OID ||
+					context->track_version))
 			add_object_address(OCLASS_COLLATION, param->paramcollid, 0,
 							   context->addrs);
 	}
@@ -1976,7 +2115,8 @@ find_expr_references_walker(Node *node,
 							   context->addrs);
 		/* the collation might not be referenced anywhere else, either */
 		if (OidIsValid(fselect->resultcollid) &&
-			fselect->resultcollid != DEFAULT_COLLATION_OID)
+			(fselect->resultcollid != DEFAULT_COLLATION_OID ||
+			 context->track_version))
 			add_object_address(OCLASS_COLLATION, fselect->resultcollid, 0,
 							   context->addrs);
 	}
@@ -2007,7 +2147,8 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* the collation might not be referenced anywhere else, either */
 		if (OidIsValid(relab->resultcollid) &&
-			relab->resultcollid != DEFAULT_COLLATION_OID)
+			(relab->resultcollid != DEFAULT_COLLATION_OID ||
+			context->track_version))
 			add_object_address(OCLASS_COLLATION, relab->resultcollid, 0,
 							   context->addrs);
 	}
@@ -2020,7 +2161,8 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* the collation might not be referenced anywhere else, either */
 		if (OidIsValid(iocoerce->resultcollid) &&
-			iocoerce->resultcollid != DEFAULT_COLLATION_OID)
+			(iocoerce->resultcollid != DEFAULT_COLLATION_OID ||
+			context->track_version))
 			add_object_address(OCLASS_COLLATION, iocoerce->resultcollid, 0,
 							   context->addrs);
 	}
@@ -2033,7 +2175,8 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* the collation might not be referenced anywhere else, either */
 		if (OidIsValid(acoerce->resultcollid) &&
-			acoerce->resultcollid != DEFAULT_COLLATION_OID)
+			(acoerce->resultcollid != DEFAULT_COLLATION_OID ||
+			context->track_version))
 			add_object_address(OCLASS_COLLATION, acoerce->resultcollid, 0,
 							   context->addrs);
 		/* fall through to examine arguments */
@@ -2122,7 +2265,8 @@ find_expr_references_walker(Node *node,
 			add_object_address(OCLASS_PROC, wc->endInRangeFunc, 0,
 							   context->addrs);
 		if (OidIsValid(wc->inRangeColl) &&
-			wc->inRangeColl != DEFAULT_COLLATION_OID)
+			(wc->inRangeColl != DEFAULT_COLLATION_OID ||
+			context->track_version))
 			add_object_address(OCLASS_COLLATION, wc->inRangeColl, 0,
 							   context->addrs);
 		/* fall through to examine substructure */
@@ -2267,7 +2411,9 @@ find_expr_references_walker(Node *node,
 		{
 			Oid			collid = lfirst_oid(ct);
 
-			if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
+			if (OidIsValid(collid) &&
+					(collid != DEFAULT_COLLATION_OID ||
+					 context->track_version))
 				add_object_address(OCLASS_COLLATION, collid, 0,
 								   context->addrs);
 		}
@@ -2289,7 +2435,9 @@ find_expr_references_walker(Node *node,
 		{
 			Oid			collid = lfirst_oid(ct);
 
-			if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
+			if (OidIsValid(collid) &&
+					(collid != DEFAULT_COLLATION_OID ||
+					context->track_version))
 				add_object_address(OCLASS_COLLATION, collid, 0,
 								   context->addrs);
 		}
@@ -2685,8 +2833,9 @@ record_object_address_dependencies(const ObjectAddress *depender,
 {
 	eliminate_duplicate_dependencies(referenced);
 	recordMultipleDependencies(depender,
-							   referenced->refs, NULL, referenced->numrefs,
-							   behavior);
+							   referenced->refs, referenced->numrefs,
+							   behavior,
+							   false);
 }
 
 /*
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 9d9e915979..4546789446 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -2304,7 +2304,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&colobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_AUTO,
-										DEPENDENCY_AUTO, false);
+										DEPENDENCY_AUTO, false, false);
 	}
 	else
 	{
@@ -2314,7 +2314,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&defobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_NORMAL, false);
+										DEPENDENCY_NORMAL, false, false);
 	}
 
 	/*
@@ -3638,7 +3638,8 @@ StorePartitionKey(Relation rel,
 										RelationGetRelid(rel),
 										DEPENDENCY_NORMAL,
 										DEPENDENCY_INTERNAL,
-										true /* reverse the self-deps */ );
+										true /* reverse the self-deps */,
+										false /* don't track versions */);
 
 	/*
 	 * We must invalidate the relcache so that the next
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 76fd938ce3..369b5d43f1 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -52,6 +52,7 @@
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "catalog/storage.h"
+#include "commands/defrem.h"
 #include "commands/event_trigger.h"
 #include "commands/progress.h"
 #include "commands/tablecmds.h"
@@ -74,6 +75,7 @@
 #include "utils/guc.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
+#include "utils/pg_locale.h"
 #include "utils/memutils.h"
 #include "utils/pg_rusage.h"
 #include "utils/snapmgr.h"
@@ -117,6 +119,7 @@ static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
 								bool immediate,
 								bool isvalid,
 								bool isready);
+static bool index_depends_stable_coll_order(Oid amoid);
 static void index_update_stats(Relation rel,
 							   bool hasindex,
 							   double reltuples);
@@ -1025,6 +1028,10 @@ index_create(Relation heapRelation,
 	{
 		ObjectAddress myself,
 					referenced;
+		ListCell   *lc;
+		List	   *colls = NIL,
+				   *determ_colls = NIL,
+				   *nondeterm_colls = NIL;
 
 		myself.classId = RelationRelationId;
 		myself.objectId = indexRelationId;
@@ -1115,21 +1122,75 @@ index_create(Relation heapRelation,
 			recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC);
 		}
 
-		/* Store dependency on collations */
-		/* The default collation is pinned, so don't bother recording it */
+		/* First, get all dependencies on collations for all index keys. */
 		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
 		{
-			if (OidIsValid(collationObjectId[i]) &&
-				collationObjectId[i] != DEFAULT_COLLATION_OID)
+			Oid colloid = collationObjectId[i];
+
+			if (OidIsValid(colloid))
+				colls = lappend_oid(colls, colloid);
+			else
 			{
-				referenced.classId = CollationRelationId;
-				referenced.objectId = collationObjectId[i];
-				referenced.objectSubId = 0;
+				Form_pg_attribute att = TupleDescAttr(indexTupDesc, i);
 
-				recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+				Assert(i < indexTupDesc->natts);
+
+				colls = list_concat(colls,
+									GetTypeCollations(att->atttypid, false));
 			}
 		}
 
+		/*
+		 * Then split the dependencies on whether they're deterministic or not,
+		 * removing any duplicates.
+		 */
+		foreach(lc, colls)
+		{
+			Oid c = lfirst_oid(lc);
+
+			if (!OidIsValid(c))
+				continue;
+
+			if (get_collation_isdeterministic(c))
+				determ_colls = list_append_unique_oid(determ_colls, c);
+			else
+				nondeterm_colls = list_append_unique_oid(nondeterm_colls, c);
+		}
+
+		/*
+		 * For deterministic transaction, only track the version if the AM
+		 * relies on a stable ordering.
+		 */
+		if (determ_colls)
+		{
+			bool track_version;
+
+			track_version = index_depends_stable_coll_order(indexInfo->ii_Am);
+
+			recordDependencyOnCollations(&myself, determ_colls, track_version);
+			/*
+			 * Advance the command counter so that later calls to
+			 * recordMultipleDependencies calls can see the newly-entered
+			 * pg_depend catalog tuples for the index.
+			 */
+			CommandCounterIncrement();
+		}
+
+		/*
+		 * We always record the version for dependency on non-deterministic
+		 * collations.
+		 */
+		if (nondeterm_colls)
+		{
+			recordDependencyOnCollations(&myself, nondeterm_colls, true);
+			/*
+			 * Advance the command counter so that later calls to
+			 * recordMultipleDependencies calls can see the newly-entered
+			 * pg_depend catalog tuples for the index.
+			 */
+			CommandCounterIncrement();
+		}
+
 		/* Store dependency on operator classes */
 		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
 		{
@@ -1143,21 +1204,29 @@ index_create(Relation heapRelation,
 		/* Store dependencies on anything mentioned in index expressions */
 		if (indexInfo->ii_Expressions)
 		{
+			/* recordDependencyOnSingleRelExpr get rid of duplicate entries */
 			recordDependencyOnSingleRelExpr(&myself,
 											(Node *) indexInfo->ii_Expressions,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false);
+											DEPENDENCY_AUTO, false, true);
+			/*
+			 * Advance the command counter so that later
+			 * recordMultipleDependencies calls can see the newly-entered
+			 * pg_depend catalog tuples for the index.
+			 */
+			CommandCounterIncrement();
 		}
 
 		/* Store dependencies on anything mentioned in predicate */
 		if (indexInfo->ii_Predicate)
 		{
+			/* recordDependencyOnSingleRelExpr get rid of duplicate entries */
 			recordDependencyOnSingleRelExpr(&myself,
 											(Node *) indexInfo->ii_Predicate,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false);
+											DEPENDENCY_AUTO, false, true);
 		}
 	}
 	else
@@ -1229,6 +1298,94 @@ index_create(Relation heapRelation,
 	return indexRelationId;
 }
 
+static char *
+index_check_collation_version(const ObjectAddress *otherObject,
+							  const char *version,
+							  void *userdata)
+{
+	Oid			relid = *(Oid *) userdata;
+	char	   *current_version;
+
+	/* We only care about dependencies on collations. */
+	if (otherObject->classId != CollationRelationId)
+		return NULL;
+
+	/* Compare with the current version. */
+	current_version = get_collation_version_for_oid(otherObject->objectId);
+
+	/* XXX should we warn about "disappearing" versions? */
+	if (current_version)
+	{
+		/*
+		 * We now support versioning for the underlying collation library on
+		 * this system, or previous version is unknown.
+		 */
+		if (!version || (strcmp(version, "") == 0 && strcmp(current_version,
+						"") != 0))
+		{
+			ereport(WARNING,
+					(errmsg("index \"%s\" depends on collation \"%s\" with an unknown version, and the current version is \"%s\"",
+							get_rel_name(relid),
+							get_collation_name(otherObject->objectId),
+							current_version),
+					 errdetail("The index may be corrupted due to changes in sort order."),
+					 errhint("REINDEX to avoid the risk of corruption.")));
+		}
+		else if (strcmp(current_version, version) != 0)
+		{
+			ereport(WARNING,
+				(errmsg("index \"%s\" depends on collation \"%s\" version \"%s\", but the current version is \"%s\"",
+						get_rel_name(relid),
+						get_collation_name(otherObject->objectId),
+						version,
+						current_version),
+				 errdetail("The index may be corrupted due to changes in sort order."),
+				 errhint("REINDEX to avoid the risk of corruption.")));
+		}
+	}
+
+	return NULL;
+}
+
+void
+index_check_collation_versions(Oid relid)
+{
+	ObjectAddress object;
+
+	object.classId = RelationRelationId;
+	object.objectId = relid;
+	object.objectSubId = 0;
+	visitDependentObjects(&object, &index_check_collation_version, &relid);
+}
+
+static char *
+index_update_collation_version(const ObjectAddress *otherObject,
+							   const char *version,
+							   void *userdata)
+{
+	char   *current_version = (char *) userdata;
+
+	/* We only care about dependencies on collations. */
+	if (otherObject->classId != CollationRelationId)
+		return NULL;
+
+	current_version = get_collation_version_for_oid(otherObject->objectId);
+	return current_version;
+}
+
+static void
+index_update_collation_versions(Oid relid)
+{
+	ObjectAddress object;
+	NameData	current_version;
+
+	object.classId = RelationRelationId;
+	object.objectId = relid;
+	object.objectSubId = 0;
+	visitDependentObjects(&object, &index_update_collation_version,
+						  &current_version);
+}
+
 /*
  * index_concurrently_create_copy
  *
@@ -2635,6 +2792,17 @@ FormIndexDatum(IndexInfo *indexInfo,
 		elog(ERROR, "wrong number of index expressions");
 }
 
+/*
+ * Returns whether the given index access method depend on a stable collation
+ * order.
+ */
+static bool
+index_depends_stable_coll_order(Oid amoid)
+{
+	return (amoid != HASH_AM_OID &&
+			strcmp(get_am_name(amoid), "bloom") != 0);
+}
+
 
 /*
  * index_update_stats --- update pg_class entry after CREATE INDEX or REINDEX
@@ -3623,6 +3791,9 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
 	/* Close rels, but keep locks */
 	index_close(iRel, NoLock);
 	table_close(heapRelation, NoLock);
+
+	/* Record the current versions of all depended-on collations. */
+	index_update_collation_versions(indexId);
 }
 
 /*
diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 90932be831..3cc0f6651c 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -360,7 +360,7 @@ CreateConstraintEntry(const char *constraintName,
 		 */
 		recordDependencyOnSingleRelExpr(&conobject, conExpr, relId,
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_NORMAL, false);
+										DEPENDENCY_NORMAL, false, true);
 	}
 
 	/* Post creation hook for new constraint */
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 7fdbdf0ae8..7e087fefc4 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -19,16 +19,21 @@
 #include "access/table.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_extension.h"
 #include "commands/extension.h"
 #include "miscadmin.h"
+#include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
+#include "utils/pg_locale.h"
 #include "utils/rel.h"

+static bool dependencyExists(const ObjectAddress *depender,
+				   const ObjectAddress *referenced);
 static bool isObjectPinned(const ObjectAddress *object, Relation rel);

@@ -44,34 +49,47 @@ recordDependencyOn(const ObjectAddress *depender,
 				   const ObjectAddress *referenced,
 				   DependencyType behavior)
 {
-	recordMultipleDependencies(depender, referenced, NULL, 1, behavior);
+	recordMultipleDependencies(depender, referenced, 1, behavior, false);
 }
 
 /*
- * As recordDependencyOn(), but also capture a version string so that changes
- * in the referenced object can be detected.  The meaning of the version
- * string depends on the referenced object.  Currently it is used for
- * detecting changes in collation versions.
+ * Given a list of collations, record a dependency on its underlying collation
+ * version.
  */
-void
-recordDependencyOnVersion(const ObjectAddress *depender,
-						  const ObjectAddress *referenced,
-						  const NameData *version,
-						  DependencyType behavior)
+void recordDependencyOnCollations(ObjectAddress *myself,
+								  List *collations,
+								  bool record_version)
 {
-	recordMultipleDependencies(depender, referenced, version, 1, behavior);
+	ListCell   *lc;
+
+	foreach(lc, collations)
+	{
+		ObjectAddress referenced;
+
+		referenced.classId = CollationRelationId;
+		referenced.objectId = lfirst_oid(lc);
+		referenced.objectSubId = 0;
+
+		recordMultipleDependencies(myself, &referenced, 1,
+								  DEPENDENCY_NORMAL, record_version);
+	}
 }
 
 /*
  * Record multiple dependencies (of the same kind) for a single dependent
  * object.  This has a little less overhead than recording each separately.
+ *
+ * If track_version is true, then a record could be added even if the referenced
+ * dependency is pinned, and the dependency version will be retrieved according
+ * to the referenced object kind.
+ * For now, only collation version is supported.
  */
 void
 recordMultipleDependencies(const ObjectAddress *depender,
 						   const ObjectAddress *referenced,
-						   const NameData *version,
 						   int nreferenced,
-						   DependencyType behavior)
+						   DependencyType behavior,
+						   bool track_version)
 {
 	Relation	dependDesc;
 	CatalogIndexState indstate;
@@ -79,6 +97,7 @@ recordMultipleDependencies(const ObjectAddress *depender,
 	int			i;
 	bool		nulls[Natts_pg_depend];
 	Datum		values[Natts_pg_depend];
+	char	   *version = NULL;
 
 	if (nreferenced <= 0)
 		return;					/* nothing to do */
@@ -97,12 +116,49 @@ recordMultipleDependencies(const ObjectAddress *depender,
 
 	for (i = 0; i < nreferenced; i++, referenced++)
 	{
+		bool ignore_systempin = false;
+
+		if (track_version)
+		{
+			/* Only dependency on a collation is supported. */
+			if (referenced->classId == CollationRelationId)
+			{
+				/* C and POSIX collations don't require tracking the version */
+				if (referenced->objectId == C_COLLATION_OID ||
+					referenced->objectId == POSIX_COLLATION_OID)
+					continue;
+
+				/*
+				 * We don't want to record redundant depedencies that are used
+				 * to track versions to avoid redundant warnings in case of
+				 * non-matching versions when those are checked.  Note that
+				 * callers have to take care of removing duplicated entries and
+				 * calling CommandCounterIncrement() if the dependencies are
+				 * registered in multiple calls.
+				 */
+				if (dependencyExists(depender, referenced))
+					continue;
+
+				/*
+				 * Default collation is pinned, so we need to force recording
+				 * the dependency to store the version.
+				 */
+				if (referenced->objectId == DEFAULT_COLLATION_OID)
+					ignore_systempin = true;
+				version = get_collation_version_for_oid(referenced->objectId);
+				Assert(version);
+			}
+		}
+		else
+			Assert(!version);
+
 		/*
 		 * If the referenced object is pinned by the system, there's no real
-		 * need to record dependencies on it.  This saves lots of space in
-		 * pg_depend, so it's worth the time taken to check.
+		 * need to record dependencies on it, unless we need to record a
+		 * version.  This saves lots of space in pg_depend, so it's worth the
+		 * time taken to check.
 		 */
-		if (!isObjectPinned(referenced, dependDesc))
+		if (ignore_systempin || !isObjectPinned(referenced, dependDesc))
 		{
 			/*
 			 * Record the Dependency.  Note we don't bother to check for
@@ -559,6 +615,54 @@ changeDependenciesOn(Oid refClassId, Oid oldRefObjectId,
 	return count;
 }
 
+/* dependencyExists()
+ *
+ * Test if a record exists for the given depender and referenceds addresses.
+ */
+static bool dependencyExists(const ObjectAddress *depender,
+				   const ObjectAddress *referenced)
+{
+	Relation	depRel;
+	ScanKeyData key[3];
+	SysScanDesc scan;
+	HeapTuple	tup;
+	bool	ret = false;
+
+	ScanKeyInit(&key[0],
+				Anum_pg_depend_classid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(depender->classId));
+	ScanKeyInit(&key[1],
+				Anum_pg_depend_objid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(depender->objectId));
+	ScanKeyInit(&key[2],
+				Anum_pg_depend_objsubid,
+				BTEqualStrategyNumber, F_INT4EQ,
+				Int32GetDatum(depender->objectSubId));
+
+	depRel = table_open(DependRelationId, RowExclusiveLock);
+	scan = systable_beginscan(depRel, DependDependerIndexId, true,
+							  NULL, 3, key);
+
+	while (HeapTupleIsValid(tup = systable_getnext(scan)))
+	{
+		Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
+
+		if (foundDep->refclassid == referenced->classId &&
+			foundDep->refobjid == referenced->objectId &&
+			foundDep->refobjsubid == referenced->objectSubId)
+		{
+			ret = true;
+			break;
+		}
+	}
+	systable_endscan(scan);
+	table_close(depRel, RowExclusiveLock);
+
+	return ret;
+}
+
 /*
  * isObjectPinned()
  *
diff --git a/src/backend/catalog/pg_type.c b/src/backend/catalog/pg_type.c
index cd56714968..fe14b6bd38 100644
--- a/src/backend/catalog/pg_type.c
+++ b/src/backend/catalog/pg_type.c
@@ -15,6 +15,7 @@
 #include "postgres.h"
 
 #include "access/htup_details.h"
+#include "access/relation.h"
 #include "access/table.h"
 #include "access/xact.h"
 #include "catalog/binary_upgrade.h"
@@ -512,6 +513,74 @@ TypeCreate(Oid newTypeOid,
 	return address;
 }
 
+/* Get a list of all distinct collations oid that the given type depends on. */
+List *
+GetTypeCollations(Oid typeoid, bool non_deterministic_only)
+{
+	List *result = NIL;
+	HeapTuple	tuple;
+	Form_pg_type typeTup;
+
+	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typeoid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for type %u", typeoid);
+	typeTup = (Form_pg_type) GETSTRUCT(tuple);
+
+	if (OidIsValid(typeTup->typcollation))
+	{
+		if (!non_deterministic_only ||
+				!get_collation_isdeterministic(typeTup->typcollation))
+			result = list_append_unique_oid(result, typeTup->typcollation);
+	}
+	else if (typeTup->typtype == TYPTYPE_COMPOSITE)
+	{
+		Relation rel = relation_open(typeTup->typrelid, AccessShareLock);
+		TupleDesc desc = RelationGetDescr(rel);
+
+		for (int i = 0; i < RelationGetNumberOfAttributes(rel); i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(desc, i);
+
+			if (OidIsValid(att->attcollation))
+			{
+				if (!non_deterministic_only ||
+						!get_collation_isdeterministic(att->attcollation))
+					result = list_append_unique_oid(result, att->attcollation);
+			}
+			else
+				result = list_concat_unique_oid(result,
+						GetTypeCollations(att->atttypid,
+							non_deterministic_only));
+		}
+
+		relation_close(rel, NoLock);
+	}
+	else if (typeTup->typtype == TYPTYPE_DOMAIN)
+	{
+		Assert(OidIsValid(typeTup->typbasetype));
+
+		result = list_concat_unique_oid(result,
+				GetTypeCollations(typeTup->typbasetype,
+					non_deterministic_only));
+	}
+	else if (typeTup->typtype == TYPTYPE_RANGE)
+	{
+		Oid rangeid = get_range_subtype(typeTup->oid);
+
+		Assert(OidIsValid(rangeid));
+
+		result = list_concat_unique_oid(result,
+				GetTypeCollations(rangeid, non_deterministic_only));
+	}
+	else if (OidIsValid(typeTup->typelem))
+		result = list_concat_unique_oid(result,
+				GetTypeCollations(typeTup->typelem, non_deterministic_only));
+
+	ReleaseSysCache(tuple);
+
+	return result;
+}
+
 /*
  * GenerateTypeDependencies: build the dependencies needed for a type
  *
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 78eceda848..d4eccf163f 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -273,28 +273,12 @@ Datum
 pg_collation_actual_version(PG_FUNCTION_ARGS)
 {
 	Oid			collid = PG_GETARG_OID(0);
-	HeapTuple	tp;
-	char	   *collcollate;
-	char		collprovider;
 	char	   *version;
 
-	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
-	if (!HeapTupleIsValid(tp))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-				 errmsg("collation with OID %u does not exist", collid)));
-
-	collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
-	collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
-
-	ReleaseSysCache(tp);
-
-	version = get_collation_actual_version(collprovider, collcollate);
+	version = get_collation_version_for_oid(collid);
+	Assert(version);
 
-	if (version)
-		PG_RETURN_TEXT_P(cstring_to_text(version));
-	else
-		PG_RETURN_NULL();
+	PG_RETURN_TEXT_P(cstring_to_text(version));
 }

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index d625d17bf4..2b7de111cd 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -31,6 +31,8 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "catalog/catalog.h"
+#include "catalog/index.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_inherits.h"
@@ -634,6 +636,35 @@ vacuum_open_relation(Oid relid, RangeVar *relation, int options,
 		rel_lock = false;
 	}
 
+	/*
+	 * Perform version sanity checks on the relation underlying indexes if
+	 * it's not a VACUUM FULL
+	 */
+	if (!(options & VACOPT_FULL) && onerel && !IsSystemRelation(onerel) &&
+			onerel->rd_rel->relhasindex)
+	{
+		List	   *indexoidlist;
+		ListCell   *l;
+
+		indexoidlist = RelationGetIndexList(onerel);
+		foreach(l, indexoidlist)
+		{
+			Oid			indexoid = lfirst_oid(l);
+			Relation	indexRelation;
+
+			indexRelation = index_open(indexoid, AccessShareLock);
+
+			/* Warn if any dependent collations' versions have moved. */
+			if (!indexRelation->rd_version_checked)
+			{
+				index_check_collation_versions(indexoid);
+				indexRelation->rd_version_checked = true;
+			}
+
+			index_close(indexRelation, NoLock);
+		}
+	}
+
 	/* if relation is opened, leave */
 	if (onerel)
 		return onerel;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d82fc5ab8b..f2fc427fc8 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -28,6 +28,7 @@
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/heap.h"
+#include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_statistic_ext.h"
@@ -198,6 +199,14 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 			indexRelation = index_open(indexoid, lmode);
 			index = indexRelation->rd_index;
 
+			/* Warn if any dependent collations' versions have moved. */
+			if (!IsSystemRelation(relation) &&
+					!indexRelation->rd_version_checked)
+			{
+				index_check_collation_versions(indexoid);
+				indexRelation->rd_version_checked = true;
+			}
+
 			/*
 			 * Ignore invalid indexes, since they can't safely be used for
 			 * queries.  Note that this is OK because the data structure we
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 60dab33fcb..18a2d72f91 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -57,7 +57,9 @@
 #include "access/htup_details.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_control.h"
+#include "catalog/pg_database.h"
 #include "mb/pg_wchar.h"
+#include "miscadmin.h"
 #include "utils/builtins.h"
 #include "utils/formatting.h"
 #include "utils/hsearch.h"
@@ -148,6 +150,9 @@ static char *IsoLocaleName(const char *);	/* MSVC specific */
 static void icu_set_collation_attributes(UCollator *collator, const char *loc);
 #endif
 
+static char *get_collation_actual_version(char collprovider,
+										  const char *collcollate);
+
 /*
  * pg_perm_setlocale
  *
@@ -1473,7 +1478,7 @@ pg_newlocale_from_collation(Oid collid)
  * NULL (if it doesn't support versions).  It must not return NULL for some
  * collcollate and not NULL for others.
  */
-char *
+static char *
 get_collation_actual_version(char collprovider, const char *collcollate)
 {
 	char	   *collversion = NULL;
@@ -1511,6 +1516,51 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 	return collversion;
 }
 
+/*
+ * Get provider-specific collation version string given a collation OID.
+ *
+ * As this version is used in index dependency tracking, an empty string is
+ * returned when the version is unknown, to distinguish from dependencies where
+ * the version should not be tracked, represented by a NULL version.
+ */
+char *
+get_collation_version_for_oid(Oid oid)
+{
+	HeapTuple	tp;
+	char *version = NULL;
+
+	Assert(oid != C_COLLATION_OID && oid != POSIX_COLLATION_OID);
+
+	if (oid == DEFAULT_COLLATION_OID)
+	{
+		Form_pg_database dbform;
+
+		tp = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
+		if (!HeapTupleIsValid(tp))
+			elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
+		dbform = (Form_pg_database) GETSTRUCT(tp);
+		version = get_collation_actual_version(COLLPROVIDER_LIBC,
+											   NameStr(dbform->datcollate));
+	}
+	else
+	{
+		Form_pg_collation collform;
+
+		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(oid));
+		if (!HeapTupleIsValid(tp))
+			elog(ERROR, "cache lookup failed for collation %u", oid);
+		collform = (Form_pg_collation) GETSTRUCT(tp);
+		version = get_collation_actual_version(collform->collprovider,
+											   NameStr(collform->collcollate));
+	}
+
+	ReleaseSysCache(tp);
+
+	if (!version)
+		return "";
+	else
+		return version;
+}
 
 #ifdef USE_ICU
 /*
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index ff70326474..bdf50ffe89 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -41,6 +41,7 @@
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/catalog.h"
+#include "catalog/index.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_am.h"
@@ -5623,6 +5624,7 @@ load_relcache_init_file(bool shared)
 		rel->rd_idattr = NULL;
 		rel->rd_pubactions = NULL;
 		rel->rd_statvalid = false;
+		rel->rd_version_checked = false;
 		rel->rd_statlist = NIL;
 		rel->rd_fkeyvalid = false;
 		rel->rd_fkeylist = NIL;
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 77cf0612ed..8750bfc36f 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -156,7 +156,8 @@ extern void recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 											Node *expr, Oid relId,
 											DependencyType behavior,
 											DependencyType self_behavior,
-											bool reverse_self);
+											bool reverse_self,
+											bool track_version);
 
 extern ObjectClass getObjectClass(const ObjectAddress *object);
 
@@ -176,22 +177,29 @@ extern void sort_object_addresses(ObjectAddresses *addrs);
 
 extern void free_object_addresses(ObjectAddresses *addrs);
 
+typedef char *(*VisitDependentObjectsFun) (const ObjectAddress *otherObject,
+											   const char *version,
+											   void *userdata);
+
+extern void visitDependentObjects(const ObjectAddress *object,
+								  VisitDependentObjectsFun callback,
+								  void *userdata);
+
 /* in pg_depend.c */
 
 extern void recordDependencyOn(const ObjectAddress *depender,
 							   const ObjectAddress *referenced,
 							   DependencyType behavior);
 
-extern void recordDependencyOnVersion(const ObjectAddress *depender,
-									  const ObjectAddress *referenced,
-									  const NameData *version,
-									  DependencyType behavior);
+extern void recordDependencyOnCollations(ObjectAddress *myself,
+										 List *collations,
+										 bool record_version);
 
 extern void recordMultipleDependencies(const ObjectAddress *depender,
 									   const ObjectAddress *referenced,
-									   const NameData *version,
 									   int nreferenced,
-									   DependencyType behavior);
+									   DependencyType behavior,
+									   bool track_version);
 
 extern void recordDependencyOnCurrentExtension(const ObjectAddress *object,
 											   bool isReplace);
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index a2890c1314..c619d02465 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -121,6 +121,8 @@ extern void FormIndexDatum(IndexInfo *indexInfo,
 						   Datum *values,
 						   bool *isnull);
 
+extern void index_check_collation_versions(Oid relid);
+
 extern void index_build(Relation heapRelation,
 						Relation indexRelation,
 						IndexInfo *indexInfo,
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 97890946c5..3eb5ec4fcd 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -350,6 +350,8 @@ extern void GenerateTypeDependencies(HeapTuple typeTuple,
 									 bool isDependentType,
 									 bool rebuild);
 
+extern List *GetTypeCollations(Oid typeObjectid, bool non_deterministic_only);
+
 extern void RenameTypeInternal(Oid typeOid, const char *newTypeName,
 							   Oid typeNamespace);
 
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 9cb7d91ddf..96da132c03 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -103,7 +103,7 @@ typedef struct pg_locale_struct *pg_locale_t;
 
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
-extern char *get_collation_actual_version(char collprovider, const char *collcollate);
+extern char *get_collation_version_for_oid(Oid collid);
 
 #ifdef USE_ICU
 extern int32_t icu_to_uchar(UChar **buff_uchar, const char *buff, size_t nbytes);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 44ed04dd3f..3656ea94e8 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -63,6 +63,7 @@ typedef struct RelationData
 	bool		rd_indexvalid;	/* is rd_indexlist valid? (also rd_pkindex and
 								 * rd_replidindex) */
 	bool		rd_statvalid;	/* is rd_statlist valid? */
+	bool		rd_version_checked;	/* has version check being done yet? */
 
 	/*
 	 * rd_createSubid is the ID of the highest subtransaction the rel has
diff --git a/src/test/Makefile b/src/test/Makefile
index efb206aa75..4ef0d11702 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -12,7 +12,8 @@ subdir = src/test
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
 
-SUBDIRS = perl regress isolation modules authentication recovery subscription
+SUBDIRS = perl regress isolation modules authentication recovery subscription \
+	  locale
 
 # Test suites that are not safe by default but can be run if selected
 # by the user via the whitespace-separated list in variable
@@ -37,7 +38,7 @@ endif
 # clean" etc to recurse into them.  (We must filter out those that we
 # have conditionally included into SUBDIRS above, else there will be
 # make confusion.)
-ALWAYS_SUBDIRS = $(filter-out $(SUBDIRS),examples kerberos ldap locale thread ssl)
+ALWAYS_SUBDIRS = $(filter-out $(SUBDIRS),examples kerberos ldap thread ssl)
 
 # We want to recurse to all subdirs for all standard targets, except that
 # installcheck and install should not recurse into the subdirectory "modules".
diff --git a/src/test/locale/.gitignore b/src/test/locale/.gitignore
index 620d3df425..64e1bf2a80 100644
--- a/src/test/locale/.gitignore
+++ b/src/test/locale/.gitignore
@@ -1 +1,2 @@
 /test-ctype
+/tmp_check/
diff --git a/src/test/locale/Makefile b/src/test/locale/Makefile
index 22a45b65f2..73495cf16b 100644
--- a/src/test/locale/Makefile
+++ b/src/test/locale/Makefile
@@ -4,6 +4,7 @@ subdir = src/test/locale
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
+export with_icu
 
 PROGS = test-ctype
 DIRS = de_DE.ISO8859-1 gr_GR.ISO8859-7 koi8-r koi8-to-win1251
@@ -19,3 +20,9 @@ clean distclean maintainer-clean:
 # These behave like installcheck targets.
 check-%: all
 	@$(MAKE) -C `echo $@ | sed 's/^check-//'` test
+
+check:
+	$(prove_check)
+
+installcheck:
+	$(prove_installcheck)
diff --git a/src/test/locale/t/001_index.pl b/src/test/locale/t/001_index.pl
new file mode 100644
index 0000000000..468fbb63b6
--- /dev/null
+++ b/src/test/locale/t/001_index.pl
@@ -0,0 +1,76 @@
+use strict;
+use warnings;
+
+use Config;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 12;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+#### Set up the server
+
+note "setting up data directory";
+my $node = get_new_node('main');
+$node->init;
+
+$ENV{PGHOST} = $node->host;
+$ENV{PGPORT} = $node->port;
+$node->start;
+
+sub test_index
+{
+	my ($err_like, $err_comm) = @_;
+
+	my ($ret, $out, $err) = $node->psql('postgres',
+		'SET enable_seqscan = 0;'
+		. "EXPLAIN SELECT val FROM icu1 WHERE val = '0'");
+
+	is($ret, 0, 'EXPLAIN should succeed.');
+	like($out, qr/icu1_fr/, 'Index icu1_fr should be used.');
+	like($err, $err_like, $err_comm);
+}
+
+$node->safe_psql('postgres',
+	'CREATE TABLE icu1(val text);'
+	. 'INSERT INTO icu1 SELECT i::text FROM generate_series(1, 10000) i;'
+	. 'CREATE INDEX icu1_fr ON icu1 (val COLLATE "fr-x-icu");');
+$node->safe_psql('postgres', 'VACUUM ANALYZE icu1;');
+
+test_index(qr/^$/, 'No warning should be raised');
+
+# Simulate different collation version
+$node->safe_psql('postgres',
+	"UPDATE pg_depend SET refobjversion = 'not_a_version'"
+	. " WHERE refobjversion IS NOT NULL"
+	. " AND objid::regclass::text = 'icu1_fr';");
+
+test_index(qr/index "icu1_fr" depends on collation "fr-x-icu" version "not_a_version", but the current version is/,
+	'Different collation version warning should be raised.');
+
+# Simulate unknown collation version
+$node->safe_psql('postgres',
+	"UPDATE pg_depend SET refobjversion = ''"
+	. " WHERE refobjversion IS NOT NULL"
+	. " AND objid::regclass::text = 'icu1_fr';");
+
+test_index(qr/index "icu1_fr" depends on collation "fr-x-icu" with an unknown version, and the current version is/,
+	'Unknown collation version warning should be raised.');
+
+# Simulate previously unhandled collation versioning
+$node->safe_psql('postgres',
+	"UPDATE pg_depend SET refobjversion = NULL"
+	. " WHERE refobjversion IS NOT NULL"
+	. " AND objid::regclass::text = 'icu1_fr';");
+
+test_index(qr/index "icu1_fr" depends on collation "fr-x-icu" with an unknown version, and the current version is/,
+	'Unknown collation version warning should be raised.');
+
+$node->stop;
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 60d9263a2f..09512c0f66 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1897,6 +1897,136 @@ SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
  t
 (1 row)
 
+-- collation versioning support
+CREATE TYPE t_en_fr AS (fr text COLLATE "fr-x-icu", en text COLLATE "en-x-icu");
+CREATE DOMAIN d_en_fr AS t_en_fr;
+CREATE DOMAIN d_es AS text COLLATE "es-x-icu";
+CREATE TYPE t_en_fr_ga AS (en_fr t_en_fr, ga text COLLATE "ga-x-icu");
+CREATE DOMAIN d_en_fr_ga AS t_en_fr_ga;
+CREATE TYPE t_custom AS (meh text, meh2 text);
+CREATE DOMAIN d_custom AS t_custom;
+CREATE COLLATION custom (
+    LOCALE = 'fr-x-icu', PROVIDER = 'icu'
+);
+CREATE TYPE myrange AS range (subtype = text);
+CREATE TYPE myrange_en_fr_ga AS range(subtype = t_en_fr_ga);
+CREATE TYPE mood AS ENUM ('sad', 'ok', 'happy');
+CREATE TABLE collate_test (
+    id integer,
+    t_en_fr t_en_fr,
+    d_en_fr d_en_fr,
+    d_es d_es,
+    t_en_fr_ga t_en_fr_ga,
+    d_en_fr_ga d_en_fr_ga,
+    d_en_fr_ga_arr d_en_fr_ga[],
+    myrange myrange,
+    myrange_en_fr_ga myrange_en_fr_ga,
+    mood mood
+);
+CREATE INDEX icuidx01_t_en_fr__d_es ON collate_test (t_en_fr, d_es);
+CREATE INDEX icuidx02_d_en_fr ON collate_test (d_en_fr);
+CREATE INDEX icuidx03_t_en_fr_ga ON collate_test (t_en_fr_ga);
+CREATE INDEX icuidx04_d_en_fr_ga ON collate_test (d_en_fr_ga);
+CREATE INDEX icuidx05_d_en_fr_ga_arr ON collate_test (d_en_fr_ga_arr);
+CREATE INDEX icuidx06_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).en_fr.fr = 'foo';
+CREATE INDEX icuidx07_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).ga = 'foo';
+CREATE INDEX icuidx08_d_en_fr_ga ON collate_test(id) WHERE (t_en_fr_ga) = ('foo', 'bar', 'baz');
+CREATE INDEX icuidx09_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz');
+CREATE INDEX icuidx10_d_en_fr_ga_es ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz' COLLATE "es-x-icu");
+CREATE INDEX icuidx11_d_es ON collate_test(id) WHERE (d_es) = ('foo');
+CREATE INDEX icuidx12_custom ON collate_test(id) WHERE ('foo', 'bar')::d_custom = ('foo', 'bar' collate custom)::d_custom;
+CREATE INDEX icuidx13_custom ON collate_test(id) WHERE ('foo' collate custom, 'bar')::d_custom = ('foo', 'bar')::d_custom;
+CREATE INDEX icuidx14_myrange ON collate_test(myrange);
+CREATE INDEX icuidx15_myrange_en_fr_ga ON collate_test USING gist (myrange_en_fr_ga);
+CREATE INDEX icuidx16_mood ON collate_test(id) WHERE mood > 'ok' collate "fr-x-icu";
+CREATE TABLE collate_part(id integer, val text COLLATE "en-x-icu") PARTITION BY range(id);
+CREATE TABLE collate_part_0 PARTITION OF collate_part FOR VALUES FROM (0) TO (1);
+CREATE TABLE collate_part_1 PARTITION OF collate_part FOR VALUES FROM (1) TO (1000000);
+CREATE INDEX icuidx17_part ON collate_part_1 (val);
+-- for key columns, hash indexes should record dependency on the collation but
+-- not the version
+CREATE INDEX icuidx18_hash_d_es ON collate_test USING hash (d_es);
+CREATE INDEX icuidx19_hash_id_d_es_eq ON collate_test USING hash (id) WHERE (d_es) = 'foo';
+CREATE INDEX icuidx20_hash_id_d_es_lt ON collate_test USING hash (id) WHERE (d_es) < 'foo';
+SELECT objid::regclass, refobjid::regcollation,
+CASE
+WHEN refobjversion IS NULL THEN 'version not tracked'
+ELSE CASE
+    WHEN refobjversion = pg_collation_actual_version(refobjid) THEN 'up to date'
+    ELSE 'out of date'
+    END
+END AS version
+FROM pg_depend d
+LEFT JOIN pg_class c ON c.oid = d.objid
+WHERE refclassid = 'pg_collation'::regclass
+AND coalesce(relkind, 'i') = 'i'
+AND relname LIKE 'icuidx%'
+ORDER BY 1, 2;
+           objid           |  refobjid  |       version       
+---------------------------+------------+---------------------
+ icuidx01_t_en_fr__d_es    | "en-x-icu" | up to date
+ icuidx01_t_en_fr__d_es    | "es-x-icu" | up to date
+ icuidx01_t_en_fr__d_es    | "fr-x-icu" | up to date
+ icuidx02_d_en_fr          | "en-x-icu" | up to date
+ icuidx02_d_en_fr          | "fr-x-icu" | up to date
+ icuidx03_t_en_fr_ga       | "en-x-icu" | up to date
+ icuidx03_t_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx03_t_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx04_d_en_fr_ga       | "en-x-icu" | up to date
+ icuidx04_d_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx04_d_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx05_d_en_fr_ga_arr   | "en-x-icu" | up to date
+ icuidx05_d_en_fr_ga_arr   | "fr-x-icu" | up to date
+ icuidx05_d_en_fr_ga_arr   | "ga-x-icu" | up to date
+ icuidx06_d_en_fr_ga       | "default"  | up to date
+ icuidx06_d_en_fr_ga       | "en-x-icu" | up to date
+ icuidx06_d_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx06_d_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx07_d_en_fr_ga       | "default"  | up to date
+ icuidx07_d_en_fr_ga       | "en-x-icu" | up to date
+ icuidx07_d_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx07_d_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx08_d_en_fr_ga       | "en-x-icu" | up to date
+ icuidx08_d_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx08_d_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx09_d_en_fr_ga       | "en-x-icu" | up to date
+ icuidx09_d_en_fr_ga       | "fr-x-icu" | up to date
+ icuidx09_d_en_fr_ga       | "ga-x-icu" | up to date
+ icuidx10_d_en_fr_ga_es    | "en-x-icu" | up to date
+ icuidx10_d_en_fr_ga_es    | "es-x-icu" | up to date
+ icuidx10_d_en_fr_ga_es    | "fr-x-icu" | up to date
+ icuidx10_d_en_fr_ga_es    | "ga-x-icu" | up to date
+ icuidx11_d_es             | "default"  | up to date
+ icuidx11_d_es             | "es-x-icu" | up to date
+ icuidx12_custom           | "default"  | up to date
+ icuidx12_custom           | custom     | up to date
+ icuidx13_custom           | "default"  | up to date
+ icuidx13_custom           | custom     | up to date
+ icuidx14_myrange          | "default"  | up to date
+ icuidx15_myrange_en_fr_ga | "en-x-icu" | up to date
+ icuidx15_myrange_en_fr_ga | "fr-x-icu" | up to date
+ icuidx15_myrange_en_fr_ga | "ga-x-icu" | up to date
+ icuidx16_mood             | "fr-x-icu" | up to date
+ icuidx17_part             | "en-x-icu" | up to date
+ icuidx18_hash_d_es        | "es-x-icu" | version not tracked
+ icuidx19_hash_id_d_es_eq  | "default"  | up to date
+ icuidx19_hash_id_d_es_eq  | "es-x-icu" | up to date
+ icuidx20_hash_id_d_es_lt  | "default"  | up to date
+ icuidx20_hash_id_d_es_lt  | "es-x-icu" | up to date
+(49 rows)
+
+UPDATE pg_depend SET refobjversion = 'not a version'
+WHERE refclassid = 'pg_collation'::regclass
+AND objid::regclass::text LIKE 'icuidx%'
+AND refobjversion IS NOT NULL;
+REINDEX TABLE collate_test;
+REINDEX TABLE collate_part_0;
+REINDEX TABLE collate_part_1;
+SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
+ objid 
+-------
+(0 rows)
+
 -- cleanup
 RESET search_path;
 SET client_min_messages TO warning;
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index ae95bb38a6..94b4daf4d6 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2065,15 +2065,17 @@ WHERE classid = 'pg_class'::regclass AND
                    obj                    |                           objref                           | deptype 
 ------------------------------------------+------------------------------------------------------------+---------
  index concur_reindex_ind1                | constraint concur_reindex_ind1 on table concur_reindex_tab | i
+ index concur_reindex_ind2                | collation "default"                                        | n
  index concur_reindex_ind2                | column c2 of table concur_reindex_tab                      | a
  index concur_reindex_ind3                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind3                | table concur_reindex_tab                                   | a
+ index concur_reindex_ind4                | collation "default"                                        | n
  index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind4                | column c2 of table concur_reindex_tab                      | a
  materialized view concur_reindex_matview | schema public                                              | n
  table concur_reindex_tab                 | schema public                                              | n
-(9 rows)
+(11 rows)
 
 REINDEX INDEX CONCURRENTLY concur_reindex_ind1;
 REINDEX TABLE CONCURRENTLY concur_reindex_tab;
@@ -2093,15 +2095,17 @@ WHERE classid = 'pg_class'::regclass AND
                    obj                    |                           objref                           | deptype 
 ------------------------------------------+------------------------------------------------------------+---------
  index concur_reindex_ind1                | constraint concur_reindex_ind1 on table concur_reindex_tab | i
+ index concur_reindex_ind2                | collation "default"                                        | n
  index concur_reindex_ind2                | column c2 of table concur_reindex_tab                      | a
  index concur_reindex_ind3                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind3                | table concur_reindex_tab                                   | a
+ index concur_reindex_ind4                | collation "default"                                        | n
  index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind4                | column c1 of table concur_reindex_tab                      | a
  index concur_reindex_ind4                | column c2 of table concur_reindex_tab                      | a
  materialized view concur_reindex_matview | schema public                                              | n
  table concur_reindex_tab                 | schema public                                              | n
-(9 rows)
+(11 rows)
 
 -- Check that comments are preserved
 CREATE TABLE testcomment (i int);
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 35acf91fbf..c8f1a620d2 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -716,6 +716,89 @@ INSERT INTO test33 VALUES (2, 'DEF');
 -- they end up in the same partition (but it's platform-dependent which one)
 SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
 
+-- collation versioning support
+CREATE TYPE t_en_fr AS (fr text COLLATE "fr-x-icu", en text COLLATE "en-x-icu");
+CREATE DOMAIN d_en_fr AS t_en_fr;
+CREATE DOMAIN d_es AS text COLLATE "es-x-icu";
+CREATE TYPE t_en_fr_ga AS (en_fr t_en_fr, ga text COLLATE "ga-x-icu");
+CREATE DOMAIN d_en_fr_ga AS t_en_fr_ga;
+CREATE TYPE t_custom AS (meh text, meh2 text);
+CREATE DOMAIN d_custom AS t_custom;
+
+CREATE COLLATION custom (
+    LOCALE = 'fr-x-icu', PROVIDER = 'icu'
+);
+
+CREATE TYPE myrange AS range (subtype = text);
+CREATE TYPE myrange_en_fr_ga AS range(subtype = t_en_fr_ga);
+
+CREATE TYPE mood AS ENUM ('sad', 'ok', 'happy');
+
+CREATE TABLE collate_test (
+    id integer,
+    t_en_fr t_en_fr,
+    d_en_fr d_en_fr,
+    d_es d_es,
+    t_en_fr_ga t_en_fr_ga,
+    d_en_fr_ga d_en_fr_ga,
+    d_en_fr_ga_arr d_en_fr_ga[],
+    myrange myrange,
+    myrange_en_fr_ga myrange_en_fr_ga,
+    mood mood
+);
+
+CREATE INDEX icuidx01_t_en_fr__d_es ON collate_test (t_en_fr, d_es);
+CREATE INDEX icuidx02_d_en_fr ON collate_test (d_en_fr);
+CREATE INDEX icuidx03_t_en_fr_ga ON collate_test (t_en_fr_ga);
+CREATE INDEX icuidx04_d_en_fr_ga ON collate_test (d_en_fr_ga);
+CREATE INDEX icuidx05_d_en_fr_ga_arr ON collate_test (d_en_fr_ga_arr);
+CREATE INDEX icuidx06_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).en_fr.fr = 'foo';
+CREATE INDEX icuidx07_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).ga = 'foo';
+CREATE INDEX icuidx08_d_en_fr_ga ON collate_test(id) WHERE (t_en_fr_ga) = ('foo', 'bar', 'baz');
+CREATE INDEX icuidx09_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz');
+CREATE INDEX icuidx10_d_en_fr_ga_es ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz' COLLATE "es-x-icu");
+CREATE INDEX icuidx11_d_es ON collate_test(id) WHERE (d_es) = ('foo');
+CREATE INDEX icuidx12_custom ON collate_test(id) WHERE ('foo', 'bar')::d_custom = ('foo', 'bar' collate custom)::d_custom;
+CREATE INDEX icuidx13_custom ON collate_test(id) WHERE ('foo' collate custom, 'bar')::d_custom = ('foo', 'bar')::d_custom;
+CREATE INDEX icuidx14_myrange ON collate_test(myrange);
+CREATE INDEX icuidx15_myrange_en_fr_ga ON collate_test USING gist (myrange_en_fr_ga);
+CREATE INDEX icuidx16_mood ON collate_test(id) WHERE mood > 'ok' collate "fr-x-icu";
+
+CREATE TABLE collate_part(id integer, val text COLLATE "en-x-icu") PARTITION BY range(id);
+CREATE TABLE collate_part_0 PARTITION OF collate_part FOR VALUES FROM (0) TO (1);
+CREATE TABLE collate_part_1 PARTITION OF collate_part FOR VALUES FROM (1) TO (1000000);
+CREATE INDEX icuidx17_part ON collate_part_1 (val);
+-- for key columns, hash indexes should record dependency on the collation but
+-- not the version
+CREATE INDEX icuidx18_hash_d_es ON collate_test USING hash (d_es);
+CREATE INDEX icuidx19_hash_id_d_es_eq ON collate_test USING hash (id) WHERE (d_es) = 'foo';
+CREATE INDEX icuidx20_hash_id_d_es_lt ON collate_test USING hash (id) WHERE (d_es) < 'foo';
+
+SELECT objid::regclass, refobjid::regcollation,
+CASE
+WHEN refobjversion IS NULL THEN 'version not tracked'
+ELSE CASE
+    WHEN refobjversion = pg_collation_actual_version(refobjid) THEN 'up to date'
+    ELSE 'out of date'
+    END
+END AS version
+FROM pg_depend d
+LEFT JOIN pg_class c ON c.oid = d.objid
+WHERE refclassid = 'pg_collation'::regclass
+AND coalesce(relkind, 'i') = 'i'
+AND relname LIKE 'icuidx%'
+ORDER BY 1, 2;
+
+UPDATE pg_depend SET refobjversion = 'not a version'
+WHERE refclassid = 'pg_collation'::regclass
+AND objid::regclass::text LIKE 'icuidx%'
+AND refobjversion IS NOT NULL;
+
+REINDEX TABLE collate_test;
+REINDEX TABLE collate_part_0;
+REINDEX TABLE collate_part_1;
+
+SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
 
 -- cleanup
 RESET search_path;
-- 
2.20.1

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