0003-Track-collation-versions-for-indexes-v5.patch

From 448acf7ff91debd3a8aa2f1bb1785d20fe1d3555 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Tue, 28 May 2019 14:16:29 -0400
Subject: [PATCH 3/6] Track collation versions for indexes.

Record the current version of dependent collations in pg_depend when
creating or rebuilding an index.  That version is checked against 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 beed
done to avoid checking and reporting the message multiple time in a backend
lifetime.

Author: Thomas Munro, Julien Rouhaud
Reviewed-by:
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com
---
 src/backend/catalog/dependency.c           | 143 ++++++++++++++++++---
 src/backend/catalog/heap.c                 |   7 +-
 src/backend/catalog/index.c                | 101 +++++++++++++--
 src/backend/catalog/pg_constraint.c        |   2 +-
 src/backend/catalog/pg_depend.c            |  69 +++++++---
 src/backend/catalog/pg_type.c              |  47 +++++++
 src/backend/commands/vacuum.c              |  31 +++++
 src/backend/optimizer/util/plancat.c       |   9 ++
 src/backend/utils/adt/pg_locale.c          |  39 ++++++
 src/backend/utils/cache/relcache.c         |   2 +
 src/include/catalog/dependency.h           |  21 ++-
 src/include/catalog/index.h                |   2 +
 src/include/catalog/pg_type.h              |   2 +
 src/include/utils/pg_locale.h              |   1 +
 src/include/utils/rel.h                    |   1 +
 src/test/regress/expected/create_index.out |   8 +-
 16 files changed, 425 insertions(+), 60 deletions(-)

diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 0bb1504b20..e8e3129886 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -137,6 +137,8 @@ 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 */
 } find_expr_references_context;
 
 /*
@@ -437,6 +439,63 @@ 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);
+		NameData   *new_version;
+
+		otherObject.classId = foundDep->refclassid;
+		otherObject.objectId = foundDep->refobjid;
+		otherObject.objectSubId = foundDep->refobjsubid;
+
+		new_version = callback(&otherObject, &foundDep->refobjversion,
+							   userdata);
+		if (new_version)
+		{
+			/* Make a modifyable copy. */
+			tup = heap_copytuple(tup);
+			foundDep = (Form_pg_depend) GETSTRUCT(tup);
+			foundDep->refobjversion = *new_version;
+			CatalogTupleUpdate(depRel, &tup->t_self, tup);
+			heap_freetuple(tup);
+		}
+	}
+	systable_endscan(scan);
+	table_close(depRel, RowExclusiveLock);
+}
+
 /*
  * findDependentObjects - find all objects that depend on 'object'
  *
@@ -1602,9 +1661,10 @@ 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);
 }
@@ -1631,12 +1691,14 @@ 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;
 
 	/* We gin up a rather bogus rangetable list to handle Vars */
 	MemSet(&rte, 0, sizeof(rte));
@@ -1690,9 +1752,10 @@ 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 */
@@ -1711,9 +1774,10 @@ 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);
 }
@@ -1775,6 +1839,32 @@ 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);
+			/* and its 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);
+
+				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);
+				}
+			}
 		}
 		else if (rte->rtekind == RTE_JOIN)
 		{
@@ -1808,11 +1898,13 @@ 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);
 
@@ -1902,7 +1994,8 @@ 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);
 	}
@@ -1990,7 +2083,8 @@ 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);
 	}
@@ -2021,7 +2115,8 @@ 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);
 	}
@@ -2034,7 +2129,8 @@ 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);
 	}
@@ -2047,7 +2143,8 @@ 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 */
@@ -2136,7 +2233,8 @@ 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 */
@@ -2254,7 +2352,9 @@ 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);
 		}
@@ -2276,7 +2376,9 @@ 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);
 		}
@@ -2672,8 +2774,9 @@ 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 8404904710..f9d9ef96c8 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -2273,7 +2273,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&colobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_AUTO,
-										DEPENDENCY_AUTO, false);
+										DEPENDENCY_AUTO, false, false);
 	}
 	else
 	{
@@ -2283,7 +2283,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&defobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_NORMAL, false);
+										DEPENDENCY_NORMAL, false, false);
 	}
 
 	/*
@@ -3527,7 +3527,8 @@ 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 e9955707fa..dfc0ecbf3b 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -74,6 +74,7 @@
 #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"
@@ -1116,19 +1117,26 @@ 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 */
+		/*
+		 * Store dependency on collations The C and posix collations are
+		 * pinned, so don't bother recording them
+		 */
 		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
 		{
-			if (OidIsValid(collationObjectId[i]) &&
-				collationObjectId[i] != DEFAULT_COLLATION_OID)
+			List	   *collations = NIL;
+
+			if (OidIsValid(collationObjectId[i]))
+				collations = list_make1_oid(collationObjectId[i]);
+			else
 			{
-				referenced.classId = CollationRelationId;
-				referenced.objectId = collationObjectId[i];
-				referenced.objectSubId = 0;
+				Form_pg_attribute att = TupleDescAttr(indexTupDesc, i);
+
+				Assert(i < indexTupDesc->natts);
 
-				recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+				collations = GetTypeCollations(att->atttypid);
 			}
+
+			recordDependencyOnCollations(&myself, collations);
 		}
 
 		/* Store dependency on operator classes */
@@ -1148,7 +1156,7 @@ index_create(Relation heapRelation,
 											(Node *) indexInfo->ii_Expressions,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false);
+											DEPENDENCY_AUTO, false, true);
 		}
 
 		/* Store dependencies on anything mentioned in predicate */
@@ -1158,7 +1166,7 @@ index_create(Relation heapRelation,
 											(Node *) indexInfo->ii_Predicate,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false);
+											DEPENDENCY_AUTO, false, true);
 		}
 	}
 	else
@@ -1230,6 +1238,76 @@ index_create(Relation heapRelation,
 	return indexRelationId;
 }
 
+static NameData *
+index_check_collation_version(const ObjectAddress *otherObject,
+							  const NameData *version,
+							  void *userdata)
+{
+	Oid			relid = *(Oid *) userdata;
+	NameData	current_version;
+
+	/* We only care about dependencies on collations. */
+	if (otherObject->classId != CollationRelationId)
+		return NULL;
+
+	/* Compare with the current version. */
+	get_collation_version_for_oid(otherObject->objectId, &current_version);
+	if (strncmp(NameStr(*version),
+				NameStr(current_version),
+				sizeof(NameData)) != 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),
+						NameStr(*version),
+						NameStr(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 NameData *
+index_update_collation_version(const ObjectAddress *otherObject,
+							   const NameData *version,
+							   void *userdata)
+{
+	NameData   *current_version = (NameData *) userdata;
+
+	/* We only care about dependencies on collations. */
+	if (otherObject->classId != CollationRelationId)
+		return NULL;
+
+	get_collation_version_for_oid(otherObject->objectId, current_version);
+	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
  *
@@ -3597,6 +3675,9 @@ 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 56568b0105..a271eb2e2d 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -361,7 +361,7 @@ 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 f1dc1143a7..d78df96304 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -19,6 +19,7 @@
 #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"
@@ -26,6 +27,7 @@
 #include "miscadmin.h"
 #include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
+#include "utils/pg_locale.h"
 #include "utils/rel.h"
 
 
@@ -44,22 +46,29 @@ 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)
 {
-	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, true);
+	}
 }
 
 /*
@@ -69,9 +78,9 @@ recordDependencyOnVersion(const ObjectAddress *depender,
 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 +88,7 @@ recordMultipleDependencies(const ObjectAddress *depender,
 	int			i;
 	bool		nulls[Natts_pg_depend];
 	Datum		values[Natts_pg_depend];
+	NameData	version;
 
 	if (nreferenced <= 0)
 		return;					/* nothing to do */
@@ -99,12 +109,37 @@ recordMultipleDependencies(const ObjectAddress *depender,
 
 	for (i = 0; i < nreferenced; i++, referenced++)
 	{
+		bool ignore_systempin = false;
+
+		version.data[0] = '\0';
+
+		if (track_version)
+		{
+			/* Only dependency on a collation needs to be tracked */
+			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;
+
+				/*
+				 * 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;;
+				get_collation_version_for_oid(referenced->objectId, &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
@@ -117,7 +152,7 @@ recordMultipleDependencies(const ObjectAddress *depender,
 			values[Anum_pg_depend_refclassid - 1] = ObjectIdGetDatum(referenced->classId);
 			values[Anum_pg_depend_refobjid - 1] = ObjectIdGetDatum(referenced->objectId);
 			values[Anum_pg_depend_refobjsubid - 1] = Int32GetDatum(referenced->objectSubId);
-			values[Anum_pg_depend_refobjversion - 1] = version ? NameGetDatum(version) : CStringGetDatum("");
+			values[Anum_pg_depend_refobjversion - 1] = NameGetDatum(&version);
 
 			values[Anum_pg_depend_deptype - 1] = CharGetDatum((char) behavior);
 			tup = heap_form_tuple(dependDesc->rd_att, values, nulls);
diff --git a/src/backend/catalog/pg_type.c b/src/backend/catalog/pg_type.c
index a8c1de511f..818c53d7e4 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"
@@ -511,6 +512,52 @@ TypeCreate(Oid newTypeOid,
 	return address;
 }
 
+/* Get a list of all collations that the given type depends on. */
+List *
+GetTypeCollations(Oid typeoid)
+{
+	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))
+		result = lappend_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))
+				result = lappend_oid(result, att->attcollation);
+			else
+				result = list_concat(result, GetTypeCollations(att->atttypid));
+		}
+
+		relation_close(rel, NoLock);
+	}
+	else if (typeTup->typtype == TYPTYPE_DOMAIN)
+	{
+		Assert(OidIsValid(typeTup->typbasetype));
+
+		result = list_concat(result, GetTypeCollations(typeTup->typbasetype));
+	}
+	else if (OidIsValid(typeTup->typelem))
+		result = list_concat(result, GetTypeCollations(typeTup->typelem));
+
+	ReleaseSysCache(tuple);
+
+	return result;
+}
+
 /*
  * GenerateTypeDependencies: build the dependencies needed for a type
  *
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index da1da23400..d0841ea657 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"
@@ -579,6 +581,35 @@ 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 5e889d1861..7e10568953 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 b7a4a1421e..59b46fcf52 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"
@@ -1501,6 +1503,43 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 	return collversion;
 }
 
+/*
+ * Get provider-specific collation version string given a collation OID.
+ */
+void
+get_collation_version_for_oid(Oid oid, NameData *output)
+{
+	HeapTuple	tp;
+	const char *version;
+
+	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));
+	}
+
+	memset(output, 0, sizeof(NameData));
+	if (version)
+		strncpy(NameStr(*output), version, sizeof(NameData));
+	ReleaseSysCache(tp);
+}
 
 #ifdef USE_ICU
 /*
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 50f8912c13..4fed56a17c 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/partition.h"
@@ -5637,6 +5638,7 @@ 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 b5d3276e77..eb34616635 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 +177,28 @@ extern void sort_object_addresses(ObjectAddresses *addrs);
 
 extern void free_object_addresses(ObjectAddresses *addrs);
 
+typedef NameData *(*VisitDependentObjectsFun) (const ObjectAddress *otherObject,
+											   const NameData *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);
 
 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 27d9e537d3..f8b7a5ed54 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 0c273a0449..a38fd566ff 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -335,6 +335,8 @@ extern void GenerateTypeDependencies(Oid typeObjectId,
 									 bool isDependentType,
 									 bool rebuild);
 
+extern List *GetTypeCollations(Oid typeObjectid);
+
 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 b4b3aa5843..023ef693e1 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -104,6 +104,7 @@ 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 void get_collation_version_for_oid(Oid collid, NameData *output);
 
 #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 31d8a1a10e..c6ed5d3e5a 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -62,6 +62,7 @@ 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/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 645ae2cf34..46c0820eb3 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2003,15 +2003,17 @@ 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;
@@ -2031,15 +2033,17 @@ 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);
-- 
2.20.1