Fix handling of collations in multi-row VALUES constructs.

Per spec we ought to apply select_common_collation() across the expressions
in each column of the VALUES table.  The original coding was just taking
the first row and assuming it was representative.

This patch adds a field to struct RangeTblEntry to carry the resolved
collations, so initdb is forced for changes in stored rule representation.

src/backend/catalog/dependency.c

@@ -1671,10 +1671,15 @@ find_expr_references_walker(Node *node,
 		/*
 		 * Add whole-relation refs for each plain relation mentioned in the
 		 * subquery's rtable, as well as refs for any datatypes and collations
-		 * used in a RECORD function's output.  (Note: query_tree_walker takes
-		 * care of recursing into RTE_FUNCTION RTEs, subqueries, etc, so no
-		 * need to do that here.  But keep it from looking at join alias
-		 * lists.)
+		 * used in a RECORD function's output.
+		 *
+		 * Note: query_tree_walker takes care of recursing into RTE_FUNCTION
+		 * RTEs, subqueries, etc, so no need to do that here.  But keep it
+		 * from looking at join alias lists.
+		 *
+		 * Note: we don't need to worry about collations mentioned in
+		 * RTE_VALUES or RTE_CTE RTEs, because those must just duplicate
+		 * collations referenced in other parts of the Query.
 		 */
 		foreach(lc, query->rtable)
 		{

src/backend/nodes/copyfuncs.c

@@ -1951,6 +1951,7 @@ _copyRangeTblEntry(RangeTblEntry *from)
 	COPY_NODE_FIELD(funccoltypmods);
 	COPY_NODE_FIELD(funccolcollations);
 	COPY_NODE_FIELD(values_lists);
+	COPY_NODE_FIELD(values_collations);
 	COPY_STRING_FIELD(ctename);
 	COPY_SCALAR_FIELD(ctelevelsup);
 	COPY_SCALAR_FIELD(self_reference);

src/backend/nodes/equalfuncs.c

@@ -2310,6 +2310,7 @@ _equalRangeTblEntry(RangeTblEntry *a, RangeTblEntry *b)
 	COMPARE_NODE_FIELD(funccoltypmods);
 	COMPARE_NODE_FIELD(funccolcollations);
 	COMPARE_NODE_FIELD(values_lists);
+	COMPARE_NODE_FIELD(values_collations);
 	COMPARE_STRING_FIELD(ctename);
 	COMPARE_SCALAR_FIELD(ctelevelsup);
 	COMPARE_SCALAR_FIELD(self_reference);

src/backend/nodes/outfuncs.c

@@ -2324,6 +2324,7 @@ _outRangeTblEntry(StringInfo str, RangeTblEntry *node)
 			break;
 		case RTE_VALUES:
 			WRITE_NODE_FIELD(values_lists);
+			WRITE_NODE_FIELD(values_collations);
 			break;
 		case RTE_CTE:
 			WRITE_STRING_FIELD(ctename);

src/backend/nodes/readfuncs.c

@@ -1203,6 +1203,7 @@ _readRangeTblEntry(void)
 			break;
 		case RTE_VALUES:
 			READ_NODE_FIELD(values_lists);
+			READ_NODE_FIELD(values_collations);
 			break;
 		case RTE_CTE:
 			READ_STRING_FIELD(ctename);

src/backend/optimizer/plan/setrefs.c

@@ -216,6 +216,7 @@ set_plan_references(PlannerGlobal *glob, Plan *plan,
 		newrte->funccoltypmods = NIL;
 		newrte->funccolcollations = NIL;
 		newrte->values_lists = NIL;
+		newrte->values_collations = NIL;
 		newrte->ctecoltypes = NIL;
 		newrte->ctecoltypmods = NIL;
 		newrte->ctecolcollations = NIL;

src/backend/parser/analyze.c

@@ -536,7 +536,9 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		 * RTE.
 		 */
 		List	   *exprsLists = NIL;
+		List	   *collations = NIL;
 		int			sublist_length = -1;
+		int			i;
 
 		foreach(lc, selectStmt->valuesLists)
 		{
@@ -573,13 +575,26 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 			 * We must assign collations now because assign_query_collations
 			 * doesn't process rangetable entries.  We just assign all the
 			 * collations independently in each row, and don't worry about
-			 * whether they are consistent vertically either.
+			 * whether they are consistent vertically.  The outer INSERT query
+			 * isn't going to care about the collations of the VALUES columns,
+			 * so it's not worth the effort to identify a common collation for
+			 * each one here.  (But note this does have one user-visible
+			 * consequence: INSERT ... VALUES won't complain about conflicting
+			 * explicit COLLATEs in a column, whereas the same VALUES
+			 * construct in another context would complain.)
 			 */
 			assign_list_collations(pstate, sublist);
 
 			exprsLists = lappend(exprsLists, sublist);
 		}
 
+		/*
+		 * Although we don't really need collation info, let's just make sure
+		 * we provide a correctly-sized list in the VALUES RTE.
+		 */
+		for (i = 0; i < sublist_length; i++)
+			collations = lappend_oid(collations, InvalidOid);
+
 		/*
 		 * There mustn't have been any table references in the expressions,
 		 * else strange things would happen, like Cartesian products of those
@@ -610,7 +625,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		/*
 		 * Generate the VALUES RTE
 		 */
-		rte = addRangeTableEntryForValues(pstate, exprsLists, NULL, true);
+		rte = addRangeTableEntryForValues(pstate, exprsLists, collations,
+										  NULL, true);
 		rtr = makeNode(RangeTblRef);
 		/* assume new rte is at end */
 		rtr->rtindex = list_length(pstate->p_rtable);
@@ -989,11 +1005,10 @@ static Query *
 transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 {
 	Query	   *qry = makeNode(Query);
-	List	   *exprsLists = NIL;
+	List	   *exprsLists;
+	List	   *collations;
 	List	  **colexprs = NULL;
-	Oid		   *coltypes = NULL;
 	int			sublist_length = -1;
-	List	   *newExprsLists;
 	RangeTblEntry *rte;
 	RangeTblRef *rtr;
 	ListCell   *lc;
@@ -1021,9 +1036,13 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 	}
 
 	/*
-	 * For each row of VALUES, transform the raw expressions and gather type
-	 * information.  This is also a handy place to reject DEFAULT nodes, which
-	 * the grammar allows for simplicity.
+	 * For each row of VALUES, transform the raw expressions.  This is also a
+	 * handy place to reject DEFAULT nodes, which the grammar allows for
+	 * simplicity.
+	 *
+	 * Note that the intermediate representation we build is column-organized
+	 * not row-organized.  That simplifies the type and collation processing
+	 * below.
 	 */
 	foreach(lc, stmt->valuesLists)
 	{
@@ -1041,9 +1060,8 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 		{
 			/* Remember post-transformation length of first sublist */
 			sublist_length = list_length(sublist);
-			/* and allocate arrays for per-column info */
+			/* and allocate array for per-column lists */
 			colexprs = (List **) palloc0(sublist_length * sizeof(List *));
-			coltypes = (Oid *) palloc0(sublist_length * sizeof(Oid));
 		}
 		else if (sublist_length != list_length(sublist))
 		{
@@ -1054,8 +1072,6 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 										exprLocation((Node *) sublist))));
 		}
 
-		exprsLists = lappend(exprsLists, sublist);
-
 		/* Check for DEFAULT and build per-column expression lists */
 		i = 0;
 		foreach(lc2, sublist)
@@ -1070,48 +1086,77 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 			colexprs[i] = lappend(colexprs[i], col);
 			i++;
 		}
+
+		/* Release sub-list's cells to save memory */
+		list_free(sublist);
 	}
 
 	/*
 	 * Now resolve the common types of the columns, and coerce everything to
-	 * those types.
+	 * those types.  Then identify the common collation, if any, of each
+	 * column.
+	 *
+	 * We must do collation processing now because (1) assign_query_collations
+	 * doesn't process rangetable entries, and (2) we need to label the VALUES
+	 * RTE with column collations for use in the outer query.  We don't
+	 * consider conflict of implicit collations to be an error here; instead
+	 * the column will just show InvalidOid as its collation, and you'll get
+	 * a failure later if that results in failure to resolve a collation.
+	 *
+	 * Note we modify the per-column expression lists in-place.
 	 */
+	collations = NIL;
 	for (i = 0; i < sublist_length; i++)
 	{
-		coltypes[i] = select_common_type(pstate, colexprs[i], "VALUES", NULL);
-	}
+		Oid		coltype;
+		Oid		colcoll;
 
-	newExprsLists = NIL;
-	foreach(lc, exprsLists)
-	{
-		List	   *sublist = (List *) lfirst(lc);
-		List	   *newsublist = NIL;
+		coltype = select_common_type(pstate, colexprs[i], "VALUES", NULL);
 
-		i = 0;
-		foreach(lc2, sublist)
+		foreach(lc, colexprs[i])
 		{
-			Node	   *col = (Node *) lfirst(lc2);
+			Node	   *col = (Node *) lfirst(lc);
 
-			col = coerce_to_common_type(pstate, col, coltypes[i], "VALUES");
-			newsublist = lappend(newsublist, col);
-			i++;
+			col = coerce_to_common_type(pstate, col, coltype, "VALUES");
+			lfirst(lc) = (void *) col;
 		}
 
-		/*
-		 * We must assign collations now because assign_query_collations
-		 * doesn't process rangetable entries.  We just assign all the
-		 * collations independently in each row, and don't worry about whether
-		 * they are consistent vertically either.
-		 */
-		assign_list_collations(pstate, newsublist);
+		colcoll = select_common_collation(pstate, colexprs[i], true);
 
-		newExprsLists = lappend(newExprsLists, newsublist);
+		collations = lappend_oid(collations, colcoll);
+	}
+
+	/*
+	 * Finally, rearrange the coerced expressions into row-organized lists.
+	 */
+	exprsLists = NIL;
+	foreach(lc, colexprs[0])
+	{
+		Node	   *col = (Node *) lfirst(lc);
+		List	   *sublist;
+
+		sublist = list_make1(col);
+		exprsLists = lappend(exprsLists, sublist);
+	}
+	list_free(colexprs[0]);
+	for (i = 1; i < sublist_length; i++)
+	{
+		forboth(lc, colexprs[i], lc2, exprsLists)
+		{
+			Node	   *col = (Node *) lfirst(lc);
+			List	   *sublist = lfirst(lc2);
+
+			/* sublist pointer in exprsLists won't need adjustment */
+			(void) lappend(sublist, col);
+		}
+		list_free(colexprs[i]);
 	}
 
 	/*
 	 * Generate the VALUES RTE
 	 */
-	rte = addRangeTableEntryForValues(pstate, newExprsLists, NULL, true);
+	rte = addRangeTableEntryForValues(pstate, exprsLists, collations,
+									  NULL, true);
 	rtr = makeNode(RangeTblRef);
 	/* assume new rte is at end */
 	rtr->rtindex = list_length(pstate->p_rtable);
@@ -1164,7 +1209,7 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("VALUES must not contain table references"),
 				 parser_errposition(pstate,
-						   locate_var_of_level((Node *) newExprsLists, 0))));
+						   locate_var_of_level((Node *) exprsLists, 0))));
 
 	/*
 	 * Another thing we can't currently support is NEW/OLD references in rules
@@ -1173,13 +1218,13 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 	 * This is a shame.  FIXME
 	 */
 	if (list_length(pstate->p_rtable) != 1 &&
-		contain_vars_of_level((Node *) newExprsLists, 0))
+		contain_vars_of_level((Node *) exprsLists, 0))
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("VALUES must not contain OLD or NEW references"),
 				 errhint("Use SELECT ... UNION ALL ... instead."),
 				 parser_errposition(pstate,
-						   locate_var_of_level((Node *) newExprsLists, 0))));
+						   locate_var_of_level((Node *) exprsLists, 0))));
 
 	qry->rtable = pstate->p_rtable;
 	qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);
@@ -1191,13 +1236,13 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 				(errcode(ERRCODE_GROUPING_ERROR),
 				 errmsg("cannot use aggregate function in VALUES"),
 				 parser_errposition(pstate,
-						   locate_agg_of_level((Node *) newExprsLists, 0))));
+						   locate_agg_of_level((Node *) exprsLists, 0))));
 	if (pstate->p_hasWindowFuncs)
 		ereport(ERROR,
 				(errcode(ERRCODE_WINDOWING_ERROR),
 				 errmsg("cannot use window function in VALUES"),
 				 parser_errposition(pstate,
-								locate_windowfunc((Node *) newExprsLists))));
+								locate_windowfunc((Node *) exprsLists))));
 
 	assign_query_collations(pstate, qry);
 

src/backend/parser/parse_relation.c

@@ -1220,6 +1220,7 @@ addRangeTableEntryForFunction(ParseState *pstate,
 RangeTblEntry *
 addRangeTableEntryForValues(ParseState *pstate,
 							List *exprs,
+							List *collations,
 							Alias *alias,
 							bool inFromCl)
 {
@@ -1233,6 +1234,7 @@ addRangeTableEntryForValues(ParseState *pstate,
 	rte->relid = InvalidOid;
 	rte->subquery = NULL;
 	rte->values_lists = exprs;
+	rte->values_collations = collations;
 	rte->alias = alias;
 
 	eref = alias ? copyObject(alias) : makeAlias(refname, NIL);
@@ -1657,7 +1659,9 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						ListCell   *l3;
 						int			attnum = 0;
 
-						forthree(l1, rte->funccoltypes, l2, rte->funccoltypmods, l3, rte->funccolcollations)
+						forthree(l1, rte->funccoltypes,
+								 l2, rte->funccoltypmods,
+								 l3, rte->funccolcollations)
 						{
 							Oid			attrtype = lfirst_oid(l1);
 							int32		attrtypmod = lfirst_int(l2);
@@ -1687,12 +1691,15 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 			{
 				/* Values RTE */
 				ListCell   *aliasp_item = list_head(rte->eref->colnames);
-				ListCell   *lc;
+				ListCell   *lcv;
+				ListCell   *lcc;
 
 				varattno = 0;
-				foreach(lc, (List *) linitial(rte->values_lists))
+				forboth(lcv, (List *) linitial(rte->values_lists),
+						lcc, rte->values_collations)
 				{
-					Node	   *col = (Node *) lfirst(lc);
+					Node	   *col = (Node *) lfirst(lcv);
+					Oid			colcollation = lfirst_oid(lcc);
 
 					varattno++;
 					if (colnames)
@@ -1712,7 +1719,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						varnode = makeVar(rtindex, varattno,
 										  exprType(col),
 										  exprTypmod(col),
-										  exprCollation(col),
+										  colcollation,
 										  sublevels_up);
 						varnode->location = location;
 						*colvars = lappend(*colvars, varnode);
@@ -1789,7 +1796,9 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 				ListCell   *lcc;
 
 				varattno = 0;
-				forthree(lct, rte->ctecoltypes, lcm, rte->ctecoltypmods, lcc, rte->ctecolcollations)
+				forthree(lct, rte->ctecoltypes,
+						 lcm, rte->ctecoltypmods,
+						 lcc, rte->ctecolcollations)
 				{
 					Oid			coltype = lfirst_oid(lct);
 					int32		coltypmod = lfirst_int(lcm);
@@ -2116,6 +2125,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 		case RTE_VALUES:
 			{
 				/* Values RTE --- get type info from first sublist */
+				/* collation is stored separately, though */
 				List	   *collist = (List *) linitial(rte->values_lists);
 				Node	   *col;
 
@@ -2125,7 +2135,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 				col = (Node *) list_nth(collist, attnum - 1);
 				*vartype = exprType(col);
 				*vartypmod = exprTypmod(col);
-				*varcollid = exprCollation(col);
+				*varcollid = list_nth_oid(rte->values_collations, attnum - 1);
 			}
 			break;
 		case RTE_JOIN:

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201104051
+#define CATALOG_VERSION_NO	201104181
 
 #endif

src/include/nodes/parsenodes.h

@@ -725,7 +725,7 @@ typedef struct RangeTblEntry
 	 *
 	 * If the function returns RECORD, funccoltypes lists the column types
 	 * declared in the RTE's column type specification, funccoltypmods lists
-	 * their declared typmods, funccolcollations their collations. Otherwise,
+	 * their declared typmods, funccolcollations their collations.  Otherwise,
 	 * those fields are NIL.
 	 */
 	Node	   *funcexpr;		/* expression tree for func call */
@@ -737,6 +737,7 @@ typedef struct RangeTblEntry
 	 * Fields valid for a values RTE (else NIL):
 	 */
 	List	   *values_lists;	/* list of expression lists */
+	List	   *values_collations;		/* OID list of column collation OIDs */
 
 	/*
 	 * Fields valid for a CTE RTE (else NULL/zero):

src/include/parser/parse_relation.h

@@ -63,6 +63,7 @@ extern RangeTblEntry *addRangeTableEntryForFunction(ParseState *pstate,
 							  bool inFromCl);
 extern RangeTblEntry *addRangeTableEntryForValues(ParseState *pstate,
 							List *exprs,
+							List *collations,
 							Alias *alias,
 							bool inFromCl);
 extern RangeTblEntry *addRangeTableEntryForJoin(ParseState *pstate,

src/test/regress/expected/collate.out

@@ -460,6 +460,14 @@ ERROR:  recursive query "foo" column 1 has collation "C" in non-recursive term b
 LINE 2:    (SELECT x FROM (VALUES('a' COLLATE "C"),('b')) t(x)
                    ^
 HINT:  Use the COLLATE clause to set the collation of the non-recursive term.
+SELECT a, b, a < b as lt FROM
+  (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
+ a | b | lt 
+---+---+----
+ a | B | f
+ A | b | t
+(2 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"

src/test/regress/sql/collate.sql

@@ -154,6 +154,9 @@ WITH RECURSIVE foo(x) AS
    SELECT (x || 'c') COLLATE "POSIX" FROM foo WHERE length(x) < 10)
 SELECT * FROM foo;
 
+SELECT a, b, a < b as lt FROM
+  (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
+
 
 -- casting