Make a code-cleanup pass over the collations patch.

This patch is almost entirely cosmetic --- mostly cleaning up a lot of
neglected comments, and fixing code layout problems in places where the
patch made lines too long and then pgindent did weird things with that.
I did find a bug-of-omission in equalTupleDescs().

src/backend/access/common/tupdesc.c

@@ -360,6 +360,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->attinhcount != attr2->attinhcount)
 			return false;
+		if (attr1->attcollation != attr2->attcollation)
+			return false;
 		/* attacl and attoptions are not even present... */
 	}
 
@@ -611,7 +613,9 @@ BuildDescForRelation(List *schema)
  * BuildDescFromLists
  *
  * Build a TupleDesc given lists of column names (as String nodes),
- * column type OIDs, and column typmods.  No constraints are generated.
+ * column type OIDs, typmods, and collation OIDs.
+ *
+ * No constraints are generated.
  *
  * This is essentially a cut-down version of BuildDescForRelation for use
  * with functions returning RECORD.

src/backend/catalog/dependency.c

@@ -2227,14 +2227,16 @@ getObjectDescription(const ObjectAddress *object)
 		case OCLASS_COLLATION:
 			{
 				HeapTuple	collTup;
+				Form_pg_collation coll;
 
 				collTup = SearchSysCache1(COLLOID,
 										  ObjectIdGetDatum(object->objectId));
 				if (!HeapTupleIsValid(collTup))
 					elog(ERROR, "cache lookup failed for collation %u",
 						 object->objectId);
+				coll = (Form_pg_collation) GETSTRUCT(collTup);
 				appendStringInfo(&buffer, _("collation %s"),
-				NameStr(((Form_pg_collation) GETSTRUCT(collTup))->collname));
+								 NameStr(coll->collname));
 				ReleaseSysCache(collTup);
 				break;
 			}

src/backend/catalog/heap.c

@@ -644,7 +644,7 @@ AddNewAttributeTuples(Oid new_rel_oid,
 
 	/*
 	 * First we add the user attributes.  This is also a convenient place to
-	 * add dependencies on their datatypes.
+	 * add dependencies on their datatypes and collations.
 	 */
 	for (i = 0; i < natts; i++)
 	{
@@ -666,7 +666,9 @@ AddNewAttributeTuples(Oid new_rel_oid,
 		referenced.objectSubId = 0;
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 
-		if (OidIsValid(attr->attcollation))
+		/* The default collation is pinned, so don't bother recording it */
+		if (OidIsValid(attr->attcollation) &&
+			attr->attcollation != DEFAULT_COLLATION_OID)
 		{
 			referenced.classId = CollationRelationId;
 			referenced.objectId = attr->attcollation;
@@ -921,7 +923,7 @@ AddNewRelationType(const char *typeName,
 				   -1,			/* typmod */
 				   0,			/* array dimensions for typBaseType */
 				   false,		/* Type NOT NULL */
-				   InvalidOid); /* typcollation */
+				   InvalidOid); /* rowtypes never have a collation */
 }
 
 /* --------------------------------
@@ -1183,7 +1185,7 @@ heap_create_with_catalog(const char *relname,
 				   -1,			/* typmod */
 				   0,			/* array dimensions for typBaseType */
 				   false,		/* Type NOT NULL */
-				   InvalidOid); /* typcollation */
+				   InvalidOid); /* rowtypes never have a collation */
 
 		pfree(relarrayname);
 	}

src/backend/catalog/index.c

@@ -351,7 +351,6 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->atthasdef = false;
 			to->attislocal = true;
 			to->attinhcount = 0;
-
 			to->attcollation = collationObjectId[i];
 		}
 		else
@@ -388,7 +387,6 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->atttypmod = -1;
 			to->attislocal = true;
-
 			to->attcollation = collationObjectId[i];
 
 			ReleaseSysCache(tuple);
@@ -653,6 +651,7 @@ UpdateIndexRelation(Oid indexoid,
  * indexColNames: column names to use for index (List of char *)
  * accessMethodObjectId: OID of index AM to use
  * tableSpaceId: OID of tablespace to use
+ * collationObjectId: array of collation OIDs, one per index column
  * classObjectId: array of index opclass OIDs, one per index column
  * coloptions: array of per-index-column indoption settings
  * reloptions: AM-specific options
@@ -871,7 +870,8 @@ index_create(Relation heapRelation,
 	 * ----------------
 	 */
 	UpdateIndexRelation(indexRelationId, heapRelationId, indexInfo,
-	   collationObjectId, classObjectId, coloptions, isprimary, is_exclusion,
+						collationObjectId, classObjectId, coloptions,
+						isprimary, is_exclusion,
 						!deferrable,
 						!concurrent);
 
@@ -965,9 +965,11 @@ index_create(Relation heapRelation,
 		}
 
 		/* Store dependency on collations */
+		/* The default collation is pinned, so don't bother recording it */
 		for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
 		{
-			if (OidIsValid(collationObjectId[i]))
+			if (OidIsValid(collationObjectId[i]) &&
+				collationObjectId[i] != DEFAULT_COLLATION_OID)
 			{
 				referenced.classId = CollationRelationId;
 				referenced.objectId = collationObjectId[i];
@@ -2445,8 +2447,8 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
 	ivinfo.num_heap_tuples = heapRelation->rd_rel->reltuples;
 	ivinfo.strategy = NULL;
 
-	state.tuplesort = tuplesort_begin_datum(TIDOID,
-										  TIDLessOperator, InvalidOid, false,
+	state.tuplesort = tuplesort_begin_datum(TIDOID, TIDLessOperator,
+											InvalidOid, false,
 											maintenance_work_mem,
 											false);
 	state.htups = state.itups = state.tups_inserted = 0;

src/backend/catalog/pg_type.c

@@ -643,8 +643,9 @@ GenerateTypeDependencies(Oid typeNamespace,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
-	/* Normal dependency from a domain to its base type's collation. */
-	if (OidIsValid(typeCollation))
+	/* Normal dependency from a domain to its collation. */
+	/* We know the default collation is pinned, so don't bother recording it */
+	if (OidIsValid(typeCollation) && typeCollation != DEFAULT_COLLATION_OID)
 	{
 		referenced.classId = CollationRelationId;
 		referenced.objectId = typeCollation;

src/backend/commands/indexcmds.c

@@ -350,7 +350,8 @@ DefineIndex(RangeVar *heapRelation,
 	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	coloptions = (int16 *) palloc(numberOfAttributes * sizeof(int16));
-	ComputeIndexAttrs(indexInfo, collationObjectId, classObjectId, coloptions, attributeList,
+	ComputeIndexAttrs(indexInfo, collationObjectId, classObjectId,
+					  coloptions, attributeList,
 					  exclusionOpNames, relationId,
 					  accessMethodName, accessMethodId,
 					  amcanorder, isconstraint);
@@ -395,7 +396,8 @@ DefineIndex(RangeVar *heapRelation,
 	indexRelationId =
 		index_create(rel, indexRelationName, indexRelationId,
 					 indexInfo, indexColNames,
-			  accessMethodId, tablespaceId, collationObjectId, classObjectId,
+					 accessMethodId, tablespaceId,
+					 collationObjectId, classObjectId,
 					 coloptions, reloptions, primary,
 					 isconstraint, deferrable, initdeferred,
 					 allowSystemTableMods,

src/backend/commands/tablecmds.c

@@ -295,7 +295,8 @@ static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recu
 static void ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				ColumnDef *colDef, bool isOid,
 				bool recurse, bool recursing, LOCKMODE lockmode);
-static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid, Oid collid);
+static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid);
+static void add_column_collation_dependency(Oid relid, int32 attnum, Oid collid);
 static void ATPrepAddOids(List **wqueue, Relation rel, bool recurse,
 			  AlterTableCmd *cmd, LOCKMODE lockmode);
 static void ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode);
@@ -4423,7 +4424,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Add needed dependency entries for the new column.
 	 */
-	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid, attribute.attcollation);
+	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
+	add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
 
 	/*
 	 * Propagate to children as appropriate.  Unlike most other ALTER
@@ -4474,7 +4476,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
  * Install a column's dependency on its datatype.
  */
 static void
-add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid, Oid collid)
+add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid)
 {
 	ObjectAddress myself,
 				referenced;
@@ -4486,9 +4488,23 @@ add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid, Oid collid)
 	referenced.objectId = typid;
 	referenced.objectSubId = 0;
 	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+}
 
-	if (collid)
+/*
+ * Install a column's dependency on its collation.
+ */
+static void
+add_column_collation_dependency(Oid relid, int32 attnum, Oid collid)
+{
+	ObjectAddress myself,
+				referenced;
+
+	/* We know the default collation is pinned, so don't bother recording it */
+	if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
 	{
+		myself.classId = RelationRelationId;
+		myself.objectId = relid;
+		myself.objectSubId = attnum;
 		referenced.classId = CollationRelationId;
 		referenced.objectId = collid;
 		referenced.objectSubId = 0;
@@ -6671,7 +6687,8 @@ ATPrepAlterColumnType(List **wqueue,
 		else
 		{
 			transform = (Node *) makeVar(1, attnum,
-				   attTup->atttypid, attTup->atttypmod, attTup->attcollation,
+										 attTup->atttypid, attTup->atttypmod,
+										 attTup->attcollation,
 										 0);
 		}
 
@@ -7052,7 +7069,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Now scan for dependencies of this column on other things.  The only
 	 * thing we should find is the dependency on the column datatype, which we
-	 * want to remove, and possibly an associated collation.
+	 * want to remove, and possibly a collation dependency.
 	 */
 	ScanKeyInit(&key[0],
 				Anum_pg_depend_classid,
@@ -7091,8 +7108,8 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	heap_close(depRel, RowExclusiveLock);
 
 	/*
-	 * Here we go --- change the recorded column type.	(Note heapTup is a
-	 * copy of the syscache entry, so okay to scribble on.)
+	 * Here we go --- change the recorded column type and collation.  (Note
+	 * heapTup is a copy of the syscache entry, so okay to scribble on.)
 	 */
 	attTup->atttypid = targettype;
 	attTup->atttypmod = targettypmod;
@@ -7112,8 +7129,9 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 
 	heap_close(attrelation, RowExclusiveLock);
 
-	/* Install dependency on new datatype */
-	add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype, targetcollid);
+	/* Install dependencies on new datatype and collation */
+	add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);
+	add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid);
 
 	/*
 	 * Drop any pg_statistic entry for the column, since it's now wrong type

src/backend/commands/typecmds.c

@@ -571,7 +571,7 @@ DefineType(List *names, List *parameters)
 				   -1,			/* typMod (Domains only) */
 				   0,			/* Array Dimensions of typbasetype */
 				   false,		/* Type NOT NULL */
-				   collation);
+				   collation);	/* type's collation */
 
 	/*
 	 * Create the array type that goes with it.
@@ -611,7 +611,7 @@ DefineType(List *names, List *parameters)
 			   -1,				/* typMod (Domains only) */
 			   0,				/* Array dimensions of typbasetype */
 			   false,			/* Type NOT NULL */
-			   collation);
+			   collation);		/* type's collation */
 
 	pfree(array_type);
 }
@@ -1069,7 +1069,7 @@ DefineDomain(CreateDomainStmt *stmt)
 				   basetypeMod, /* typeMod value */
 				   typNDims,	/* Array dimensions for base type */
 				   typNotNull,	/* Type NOT NULL */
-				   domaincoll);
+				   domaincoll);	/* type's collation */
 
 	/*
 	 * Process constraints which refer to the domain ID returned by TypeCreate
@@ -1179,7 +1179,7 @@ DefineEnum(CreateEnumStmt *stmt)
 				   -1,			/* typMod (Domains only) */
 				   0,			/* Array dimensions of typbasetype */
 				   false,		/* Type NOT NULL */
-				   InvalidOid); /* typcollation */
+				   InvalidOid); /* type's collation */
 
 	/* Enter the enum's values into pg_enum */
 	EnumValuesCreate(enumTypeOid, stmt->vals);
@@ -1219,7 +1219,7 @@ DefineEnum(CreateEnumStmt *stmt)
 			   -1,				/* typMod (Domains only) */
 			   0,				/* Array dimensions of typbasetype */
 			   false,			/* Type NOT NULL */
-			   InvalidOid);		/* typcollation */
+			   InvalidOid);		/* type's collation */
 
 	pfree(enumArrayName);
 }

src/backend/executor/nodeMergejoin.c

@@ -170,13 +170,13 @@ typedef enum
  * the two expressions from the original clause.
  *
  * In addition to the expressions themselves, the planner passes the btree
- * opfamily OID, btree strategy number (BTLessStrategyNumber or
+ * opfamily OID, collation OID, btree strategy number (BTLessStrategyNumber or
  * BTGreaterStrategyNumber), and nulls-first flag that identify the intended
  * sort ordering for each merge key.  The mergejoinable operator is an
- * equality operator in this opfamily, and the two inputs are guaranteed to be
+ * equality operator in the opfamily, and the two inputs are guaranteed to be
  * ordered in either increasing or decreasing (respectively) order according
- * to this opfamily, with nulls at the indicated end of the range.	This
- * allows us to obtain the needed comparison function from the opfamily.
+ * to the opfamily and collation, with nulls at the indicated end of the range.
+ * This allows us to obtain the needed comparison function from the opfamily.
  */
 static MergeJoinClause
 MJExamineQuals(List *mergeclauses,

src/backend/optimizer/plan/createplan.c

@@ -108,7 +108,8 @@ static TidScan *make_tidscan(List *qptlist, List *qpqual, Index scanrelid,
 			 List *tidquals);
 static FunctionScan *make_functionscan(List *qptlist, List *qpqual,
 				  Index scanrelid, Node *funcexpr, List *funccolnames,
-		  List *funccoltypes, List *funccoltypmods, List *funccolcollations);
+				  List *funccoltypes, List *funccoltypmods,
+				  List *funccolcollations);
 static ValuesScan *make_valuesscan(List *qptlist, List *qpqual,
 				Index scanrelid, List *values_lists);
 static CteScan *make_ctescan(List *qptlist, List *qpqual,
@@ -143,9 +144,9 @@ static MergeJoin *make_mergejoin(List *tlist,
 			   bool *mergenullsfirst,
 			   Plan *lefttree, Plan *righttree,
 			   JoinType jointype);
-static Sort *
-make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
-AttrNumber *sortColIdx, Oid *sortOperators, Oid *collations, bool *nullsFirst,
+static Sort *make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
+		  AttrNumber *sortColIdx, Oid *sortOperators,
+		  Oid *collations, bool *nullsFirst,
 		  double limit_tuples);
 static Plan *prepare_sort_from_pathkeys(PlannerInfo *root,
 						   Plan *lefttree, List *pathkeys,
@@ -738,7 +739,8 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 		/* Now, insert a Sort node if subplan isn't sufficiently ordered */
 		if (!pathkeys_contained_in(pathkeys, subpath->pathkeys))
 			subplan = (Plan *) make_sort(root, subplan, numsortkeys,
-						   sortColIdx, sortOperators, collations, nullsFirst,
+										 sortColIdx, sortOperators,
+										 collations, nullsFirst,
 										 best_path->limit_tuples);
 
 		subplans = lappend(subplans, subplan);
@@ -2013,10 +2015,10 @@ create_mergejoin_plan(PlannerInfo *root,
 	}
 
 	/*
-	 * Compute the opfamily/strategy/nullsfirst arrays needed by the executor.
-	 * The information is in the pathkeys for the two inputs, but we need to
-	 * be careful about the possibility of mergeclauses sharing a pathkey
-	 * (compare find_mergeclauses_for_pathkeys()).
+	 * Compute the opfamily/collation/strategy/nullsfirst arrays needed by the
+	 * executor.  The information is in the pathkeys for the two inputs, but
+	 * we need to be careful about the possibility of mergeclauses sharing a
+	 * pathkey (compare find_mergeclauses_for_pathkeys()).
 	 */
 	nClauses = list_length(mergeclauses);
 	Assert(nClauses == list_length(best_path->path_mergeclauses));
@@ -3316,13 +3318,14 @@ make_mergejoin(List *tlist,
 /*
  * make_sort --- basic routine to build a Sort plan node
  *
- * Caller must have built the sortColIdx, sortOperators, and nullsFirst
- * arrays already.	limit_tuples is as for cost_sort (in particular, pass
- * -1 if no limit)
+ * Caller must have built the sortColIdx, sortOperators, collations, and
+ * nullsFirst arrays already.
+ * limit_tuples is as for cost_sort (in particular, pass -1 if no limit)
  */
 static Sort *
 make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
-AttrNumber *sortColIdx, Oid *sortOperators, Oid *collations, bool *nullsFirst,
+		  AttrNumber *sortColIdx, Oid *sortOperators,
+		  Oid *collations, bool *nullsFirst,
 		  double limit_tuples)
 {
 	Sort	   *node = makeNode(Sort);
@@ -3378,6 +3381,11 @@ add_sort_column(AttrNumber colIdx, Oid sortOp, Oid coll, bool nulls_first,
 		 * values that < considers equal.  We need not check nulls_first
 		 * however because a lower-order column with the same sortop but
 		 * opposite nulls direction is redundant.
+		 *
+		 * We could probably consider sort keys with the same sortop and
+		 * different collations to be redundant too, but for the moment
+		 * treat them as not redundant.  This will be needed if we ever
+		 * support collations with different notions of equality.
 		 */
 		if (sortColIdx[i] == colIdx &&
 			sortOperators[numCols] == sortOp &&
@@ -3410,8 +3418,9 @@ add_sort_column(AttrNumber colIdx, Oid sortOp, Oid coll, bool nulls_first,
  *	  'adjust_tlist_in_place' is TRUE if lefttree must be modified in-place
  *
  * We must convert the pathkey information into arrays of sort key column
- * numbers and sort operator OIDs, which is the representation the executor
- * wants.  These are returned into the output parameters *p_numsortkeys etc.
+ * numbers, sort operator OIDs, collation OIDs, and nulls-first flags,
+ * which is the representation the executor wants.  These are returned into
+ * the output parameters *p_numsortkeys etc.
  *
  * If the pathkeys include expressions that aren't simple Vars, we will
  * usually need to add resjunk items to the input plan's targetlist to
@@ -3610,7 +3619,8 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 									  pathkey->pk_eclass->ec_collation,
 									  pathkey->pk_nulls_first,
 									  numsortkeys,
-						  sortColIdx, sortOperators, collations, nullsFirst);
+									  sortColIdx, sortOperators,
+									  collations, nullsFirst);
 	}
 
 	Assert(numsortkeys > 0);
@@ -3655,7 +3665,8 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 
 	/* Now build the Sort node */
 	return make_sort(root, lefttree, numsortkeys,
-			sortColIdx, sortOperators, collations, nullsFirst, limit_tuples);
+					 sortColIdx, sortOperators, collations,
+					 nullsFirst, limit_tuples);
 }
 
 /*
@@ -3701,13 +3712,15 @@ make_sort_from_sortclauses(PlannerInfo *root, List *sortcls, Plan *lefttree)
 									  exprCollation((Node *) tle->expr),
 									  sortcl->nulls_first,
 									  numsortkeys,
-						  sortColIdx, sortOperators, collations, nullsFirst);
+									  sortColIdx, sortOperators,
+									  collations, nullsFirst);
 	}
 
 	Assert(numsortkeys > 0);
 
 	return make_sort(root, lefttree, numsortkeys,
-					 sortColIdx, sortOperators, collations, nullsFirst, -1.0);
+					 sortColIdx, sortOperators, collations,
+					 nullsFirst, -1.0);
 }
 
 /*
@@ -3763,14 +3776,16 @@ make_sort_from_groupcols(PlannerInfo *root,
 									  exprCollation((Node *) tle->expr),
 									  grpcl->nulls_first,
 									  numsortkeys,
-						  sortColIdx, sortOperators, collations, nullsFirst);
+									  sortColIdx, sortOperators,
+									  collations, nullsFirst);
 		grpno++;
 	}
 
 	Assert(numsortkeys > 0);
 
 	return make_sort(root, lefttree, numsortkeys,
-					 sortColIdx, sortOperators, collations, nullsFirst, -1.0);
+					 sortColIdx, sortOperators, collations,
+					 nullsFirst, -1.0);
 }
 
 static Material *

src/backend/optimizer/plan/subselect.c

@@ -281,7 +281,7 @@ SS_assign_special_param(PlannerInfo *root)
 }
 
 /*
- * Get the datatype of the first column of the plan's output.
+ * Get the datatype/typmod/collation of the first column of the plan's output.
  *
  * This information is stored for ARRAY_SUBLINK execution and for
  * exprType()/exprTypmod()/exprCollation(), which have no way to get at the
@@ -290,7 +290,8 @@ SS_assign_special_param(PlannerInfo *root)
  * always.
  */
 static void
-get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod, Oid *colcollation)
+get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod,
+				   Oid *colcollation)
 {
 	/* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
 	if (plan->targetlist)
@@ -478,7 +479,8 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 	splan->subLinkType = subLinkType;
 	splan->testexpr = NULL;
 	splan->paramIds = NIL;
-	get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation);
+	get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
+					   &splan->firstColCollation);
 	splan->useHashTable = false;
 	splan->unknownEqFalse = unknownEqFalse;
 	splan->setParam = NIL;
@@ -976,7 +978,8 @@ SS_process_ctes(PlannerInfo *root)
 		splan->subLinkType = CTE_SUBLINK;
 		splan->testexpr = NULL;
 		splan->paramIds = NIL;
-		get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation);
+		get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod,
+						   &splan->firstColCollation);
 		splan->useHashTable = false;
 		splan->unknownEqFalse = false;
 		splan->setParam = NIL;

src/backend/parser/analyze.c

@@ -1357,9 +1357,9 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 
 	/*
 	 * Generate dummy targetlist for outer query using column names of
-	 * leftmost select and common datatypes of topmost set operation. Also
-	 * make lists of the dummy vars and their names for use in parsing ORDER
-	 * BY.
+	 * leftmost select and common datatypes/collations of topmost set
+	 * operation.  Also make lists of the dummy vars and their names for use
+	 * in parsing ORDER BY.
 	 *
 	 * Note: we use leftmostRTI as the varno of the dummy variables. It
 	 * shouldn't matter too much which RT index they have, as long as they
@@ -1371,7 +1371,9 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 	targetnames = NIL;
 	left_tlist = list_head(leftmostQuery->targetList);
 
-	forthree(lct, sostmt->colTypes, lcm, sostmt->colTypmods, lcc, sostmt->colCollations)
+	forthree(lct, sostmt->colTypes,
+			 lcm, sostmt->colTypmods,
+			 lcc, sostmt->colCollations)
 	{
 		Oid			colType = lfirst_oid(lct);
 		int32		colTypmod = lfirst_int(lcm);

src/backend/parser/parse_cte.c

@@ -286,10 +286,10 @@ analyzeCTE(ParseState *pstate, CommonTableExpr *cte)
 	else
 	{
 		/*
-		 * Verify that the previously determined output column types match
-		 * what the query really produced.	We have to check this because the
-		 * recursive term could have overridden the non-recursive term, and we
-		 * don't have any easy way to fix that.
+		 * Verify that the previously determined output column types and
+		 * collations match what the query really produced.  We have to check
+		 * this because the recursive term could have overridden the
+		 * non-recursive term, and we don't have any easy way to fix that.
 		 */
 		ListCell   *lctlist,
 				   *lctyp,
@@ -366,11 +366,11 @@ analyzeCTETargetList(ParseState *pstate, CommonTableExpr *cte, List *tlist)
 	Assert(cte->ctecolnames == NIL);
 
 	/*
-	 * We need to determine column names and types.  The alias column names
-	 * override anything coming from the query itself.	(Note: the SQL spec
-	 * says that the alias list must be empty or exactly as long as the output
-	 * column set; but we allow it to be shorter for consistency with Alias
-	 * handling.)
+	 * We need to determine column names, types, and collations.  The alias
+	 * column names override anything coming from the query itself.  (Note:
+	 * the SQL spec says that the alias list must be empty or exactly as long
+	 * as the output column set; but we allow it to be shorter for consistency
+	 * with Alias handling.)
 	 */
 	cte->ctecolnames = copyObject(cte->aliascolnames);
 	cte->ctecoltypes = cte->ctecoltypmods = cte->ctecolcollations = NIL;

src/backend/parser/parse_relation.c

@@ -1174,7 +1174,8 @@ addRangeTableEntryForFunction(ParseState *pstate,
 			eref->colnames = lappend(eref->colnames, makeString(attrname));
 			rte->funccoltypes = lappend_oid(rte->funccoltypes, attrtype);
 			rte->funccoltypmods = lappend_int(rte->funccoltypmods, attrtypmod);
-			rte->funccolcollations = lappend_oid(rte->funccolcollations, attrcollation);
+			rte->funccolcollations = lappend_oid(rte->funccolcollations,
+												 attrcollation);
 		}
 	}
 	else
@@ -1902,7 +1903,8 @@ expandTupleDesc(TupleDesc tupdesc, Alias *eref,
 			Var		   *varnode;
 
 			varnode = makeVar(rtindex, attr->attnum,
-						 attr->atttypid, attr->atttypmod, attr->attcollation,
+							  attr->atttypid, attr->atttypmod,
+							  attr->attcollation,
 							  sublevels_up);
 			varnode->location = location;
 
@@ -2009,7 +2011,7 @@ get_rte_attribute_name(RangeTblEntry *rte, AttrNumber attnum)
 
 /*
  * get_rte_attribute_type
- *		Get attribute type information from a RangeTblEntry
+ *		Get attribute type/typmod/collation information from a RangeTblEntry
  */
 void
 get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,

src/backend/parser/parse_target.c

@@ -372,7 +372,7 @@ transformAssignedExpr(ParseState *pstate,
 	Oid			type_id;		/* type of value provided */
 	Oid			attrtype;		/* type of target column */
 	int32		attrtypmod;
-	Oid			attrcollation;
+	Oid			attrcollation;	/* collation of target column */
 	Relation	rd = pstate->p_target_relation;
 
 	Assert(rd != NULL);
@@ -388,11 +388,12 @@ transformAssignedExpr(ParseState *pstate,
 
 	/*
 	 * If the expression is a DEFAULT placeholder, insert the attribute's
-	 * type/typmod into it so that exprType will report the right things. (We
-	 * expect that the eventually substituted default expression will in fact
-	 * have this type and typmod.)	Also, reject trying to update a subfield
-	 * or array element with DEFAULT, since there can't be any default for
-	 * portions of a column.
+	 * type/typmod/collation into it so that exprType etc will report the
+	 * right things.  (We expect that the eventually substituted default
+	 * expression will in fact have this type and typmod.  The collation
+	 * likely doesn't matter, but let's set it correctly anyway.)  Also,
+	 * reject trying to update a subfield or array element with DEFAULT, since
+	 * there can't be any default for portions of a column.
 	 */
 	if (expr && IsA(expr, SetToDefault))
 	{

src/backend/utils/adt/ruleutils.c

@@ -235,7 +235,8 @@ static void get_from_clause_item(Node *jtnode, Query *query,
 					 deparse_context *context);
 static void get_from_clause_alias(Alias *alias, RangeTblEntry *rte,
 					  deparse_context *context);
-static void get_from_clause_coldeflist(List *names, List *types, List *typmods, List *collations,
+static void get_from_clause_coldeflist(List *names,
+						   List *types, List *typmods, List *collations,
 						   deparse_context *context);
 static void get_opclass_name(Oid opclass, Oid actual_datatype,
 				 StringInfo buf);
@@ -6617,7 +6618,8 @@ get_from_clause_alias(Alias *alias, RangeTblEntry *rte,
  * responsible for ensuring that an alias or AS is present before it.
  */
 static void
-get_from_clause_coldeflist(List *names, List *types, List *typmods, List *collations,
+get_from_clause_coldeflist(List *names,
+						   List *types, List *typmods, List *collations,
 						   deparse_context *context)
 {
 	StringInfo	buf = context->buf;
@@ -6651,7 +6653,8 @@ get_from_clause_coldeflist(List *names, List *types, List *typmods, List *collat
 		appendStringInfo(buf, "%s %s",
 						 quote_identifier(attname),
 						 format_type_with_typemod(atttypid, atttypmod));
-		if (attcollation && attcollation != DEFAULT_COLLATION_OID)
+		if (OidIsValid(attcollation) &&
+			attcollation != get_typcollation(atttypid))
 			appendStringInfo(buf, " COLLATE %s",
 							 generate_collation_name(attcollation));
 		i++;

src/backend/utils/cache/syscache.c

@@ -277,7 +277,7 @@ static const struct cachedesc cacheinfo[] = {
 			Anum_pg_collation_collnamespace,
 			0
 		},
-		256
+		64
 	},
 	{CollationRelationId,		/* COLLOID */
 		CollationOidIndexId,
@@ -288,7 +288,7 @@ static const struct cachedesc cacheinfo[] = {
 			0,
 			0
 		},
-		256
+		64
 	},
 	{ConversionRelationId,		/* CONDEFAULT */
 		ConversionDefaultIndexId,