Revise collation derivation method and expression-tree representation.

All expression nodes now have an explicit output-collation field, unless
they are known to only return a noncollatable data type (such as boolean
or record).  Also, nodes that can invoke collation-aware functions store
a separate field that is the collation value to pass to the function.
This avoids confusion that arises when a function has collatable inputs
and noncollatable output type, or vice versa.

Also, replace the parser's on-the-fly collation assignment method with
a post-pass over the completed expression tree.  This allows us to use
a more complex (and hopefully more nearly spec-compliant) assignment
rule without paying for it in extra storage in every expression node.

Fix assorted bugs in the planner's handling of collations by making
collation one of the defining properties of an EquivalenceClass and
by converting CollateExprs into discardable RelabelType nodes during
expression preprocessing.

1 files changed, 31 insertions, 55 deletions

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 0faf52dfd79..e410818900d 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -82,7 +82,7 @@ static Datum ExecEvalParamExec(ExprState *exprstate, ExprContext *econtext,
 			  bool *isNull, ExprDoneCond *isDone);
 static Datum ExecEvalParamExtern(ExprState *exprstate, ExprContext *econtext,
 			  bool *isNull, ExprDoneCond *isDone);
-static void init_fcache(Oid foid, FuncExprState *fcache,
+static void init_fcache(Oid foid, Oid input_collation, FuncExprState *fcache,
 			MemoryContext fcacheCxt, bool needDescForSets);
 static void ShutdownFuncExpr(Datum arg);
 static TupleDesc get_cached_rowtype(Oid type_id, int32 typmod,
@@ -120,9 +120,6 @@ static Datum ExecEvalAnd(BoolExprState *andExpr, ExprContext *econtext,
 static Datum ExecEvalConvertRowtype(ConvertRowtypeExprState *cstate,
 					   ExprContext *econtext,
 					   bool *isNull, ExprDoneCond *isDone);
-static Datum ExecEvalCollateExpr(GenericExprState *exprstate,
-					ExprContext *econtext,
-					bool *isNull, ExprDoneCond *isDone);
 static Datum ExecEvalCase(CaseExprState *caseExpr, ExprContext *econtext,
 			 bool *isNull, ExprDoneCond *isDone);
 static Datum ExecEvalCaseTestExpr(ExprState *exprstate,
@@ -1179,7 +1176,7 @@ GetAttributeByName(HeapTupleHeader tuple, const char *attname, bool *isNull)
  * init_fcache - initialize a FuncExprState node during first use
  */
 static void
-init_fcache(Oid foid, FuncExprState *fcache,
+init_fcache(Oid foid, Oid input_collation, FuncExprState *fcache,
 			MemoryContext fcacheCxt, bool needDescForSets)
 {
 	AclResult	aclresult;
@@ -1205,7 +1202,8 @@ init_fcache(Oid foid, FuncExprState *fcache,
 
 	/* Set up the primary fmgr lookup information */
 	fmgr_info_cxt(foid, &(fcache->func), fcacheCxt);
-	fmgr_info_expr((Node *) fcache->xprstate.expr, &(fcache->func));
+	fmgr_info_set_collation(input_collation, &(fcache->func));
+	fmgr_info_set_expr((Node *) fcache->xprstate.expr, &(fcache->func));
 
 	/* Initialize the function call parameter struct as well */
 	InitFunctionCallInfoData(fcache->fcinfo_data, &(fcache->func),
@@ -1976,7 +1974,7 @@ ExecMakeTableFunctionResult(ExprState *funcexpr,
 		{
 			FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;
 
-			init_fcache(func->funcid, fcache,
+			init_fcache(func->funcid, func->inputcollid, fcache,
 						econtext->ecxt_per_query_memory, false);
 		}
 		returnsSet = fcache->func.fn_retset;
@@ -2255,7 +2253,8 @@ ExecEvalFunc(FuncExprState *fcache,
 	FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;
 
 	/* Initialize function lookup info */
-	init_fcache(func->funcid, fcache, econtext->ecxt_per_query_memory, true);
+	init_fcache(func->funcid, func->inputcollid, fcache,
+				econtext->ecxt_per_query_memory, true);
 
 	/* Go directly to ExecMakeFunctionResult on subsequent uses */
 	fcache->xprstate.evalfunc = (ExprStateEvalFunc) ExecMakeFunctionResult;
@@ -2277,7 +2276,8 @@ ExecEvalOper(FuncExprState *fcache,
 	OpExpr	   *op = (OpExpr *) fcache->xprstate.expr;
 
 	/* Initialize function lookup info */
-	init_fcache(op->opfuncid, fcache, econtext->ecxt_per_query_memory, true);
+	init_fcache(op->opfuncid, op->inputcollid, fcache,
+				econtext->ecxt_per_query_memory, true);
 
 	/* Go directly to ExecMakeFunctionResult on subsequent uses */
 	fcache->xprstate.evalfunc = (ExprStateEvalFunc) ExecMakeFunctionResult;
@@ -2318,7 +2318,7 @@ ExecEvalDistinct(FuncExprState *fcache,
 	{
 		DistinctExpr *op = (DistinctExpr *) fcache->xprstate.expr;
 
-		init_fcache(op->opfuncid, fcache,
+		init_fcache(op->opfuncid, op->inputcollid, fcache,
 					econtext->ecxt_per_query_memory, true);
 		Assert(!fcache->func.fn_retset);
 	}
@@ -2395,7 +2395,7 @@ ExecEvalScalarArrayOp(ScalarArrayOpExprState *sstate,
 	 */
 	if (sstate->fxprstate.func.fn_oid == InvalidOid)
 	{
-		init_fcache(opexpr->opfuncid, &sstate->fxprstate,
+		init_fcache(opexpr->opfuncid, opexpr->inputcollid, &sstate->fxprstate,
 					econtext->ecxt_per_query_memory, true);
 		Assert(!sstate->fxprstate.func.fn_retset);
 	}
@@ -2754,20 +2754,6 @@ ExecEvalConvertRowtype(ConvertRowtypeExprState *cstate,
 }
 
 /* ----------------------------------------------------------------
- *		ExecEvalCollateExpr
- *
- *		Evaluate a CollateExpr node.
- * ----------------------------------------------------------------
- */
-static Datum
-ExecEvalCollateExpr(GenericExprState *exprstate,
-					ExprContext *econtext,
-					bool *isNull, ExprDoneCond *isDone)
-{
-	return ExecEvalExpr(exprstate->arg, econtext, isNull, isDone);
-}
-
-/* ----------------------------------------------------------------
  *		ExecEvalCase
  *
  *		Evaluate a CASE clause. Will have boolean expressions
@@ -3542,7 +3528,7 @@ ExecEvalNullIf(FuncExprState *nullIfExpr,
 	{
 		NullIfExpr *op = (NullIfExpr *) nullIfExpr->xprstate.expr;
 
-		init_fcache(op->opfuncid, nullIfExpr,
+		init_fcache(op->opfuncid, op->inputcollid, nullIfExpr,
 					econtext->ecxt_per_query_memory, true);
 		Assert(!nullIfExpr->func.fn_retset);
 	}
@@ -4129,9 +4115,8 @@ ExecEvalArrayCoerceExpr(ArrayCoerceExprState *astate,
 		/* Set up the primary fmgr lookup information */
 		fmgr_info_cxt(acoerce->elemfuncid, &(astate->elemfunc),
 					  econtext->ecxt_per_query_memory);
-
-		/* Initialize additional info */
-		fmgr_info_expr((Node *) acoerce, &(astate->elemfunc));
+		/* Note: coercion functions are assumed to not use collation */
+		fmgr_info_set_expr((Node *) acoerce, &(astate->elemfunc));
 	}
 
 	/*
@@ -4400,6 +4385,18 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) fstate;
 			}
 			break;
+		case T_NullIfExpr:
+			{
+				NullIfExpr *nullifexpr = (NullIfExpr *) node;
+				FuncExprState *fstate = makeNode(FuncExprState);
+
+				fstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalNullIf;
+				fstate->args = (List *)
+					ExecInitExpr((Expr *) nullifexpr->args, parent);
+				fstate->func.fn_oid = InvalidOid;		/* not initialized */
+				state = (ExprState *) fstate;
+			}
+			break;
 		case T_ScalarArrayOpExpr:
 			{
 				ScalarArrayOpExpr *opexpr = (ScalarArrayOpExpr *) node;
@@ -4551,16 +4548,6 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) cstate;
 			}
 			break;
-		case T_CollateExpr:
-			{
-				CollateExpr *collate = (CollateExpr *) node;
-				GenericExprState *gstate = makeNode(GenericExprState);
-
-				gstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalCollateExpr;
-				gstate->arg = ExecInitExpr(collate->arg, parent);
-				state = (ExprState *) gstate;
-			}
-			break;
 		case T_CaseExpr:
 			{
 				CaseExpr   *caseexpr = (CaseExpr *) node;
@@ -4713,11 +4700,11 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				Assert(list_length(rcexpr->opfamilies) == nopers);
 				rstate->funcs = (FmgrInfo *) palloc(nopers * sizeof(FmgrInfo));
 				i = 0;
-				forthree(l, rcexpr->opnos, l2, rcexpr->opfamilies, l3, rcexpr->collids)
+				forthree(l, rcexpr->opnos, l2, rcexpr->opfamilies, l3, rcexpr->inputcollids)
 				{
 					Oid			opno = lfirst_oid(l);
 					Oid			opfamily = lfirst_oid(l2);
-					Oid			collid = lfirst_oid(l3);
+					Oid			inputcollid = lfirst_oid(l3);
 					int			strategy;
 					Oid			lefttype;
 					Oid			righttype;
@@ -4739,7 +4726,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 					 * does this code.
 					 */
 					fmgr_info(proc, &(rstate->funcs[i]));
-					fmgr_info_collation(collid, &(rstate->funcs[i]));
+					fmgr_info_set_collation(inputcollid, &(rstate->funcs[i]));
 					i++;
 				}
 				state = (ExprState *) rstate;
@@ -4799,7 +4786,8 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				 * code.
 				 */
 				fmgr_info(typentry->cmp_proc, &(mstate->cfunc));
-				fmgr_info_collation(minmaxexpr->collid, &(mstate->cfunc));
+				fmgr_info_set_collation(minmaxexpr->inputcollid,
+										&(mstate->cfunc));
 				state = (ExprState *) mstate;
 			}
 			break;
@@ -4836,18 +4824,6 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) xstate;
 			}
 			break;
-		case T_NullIfExpr:
-			{
-				NullIfExpr *nullifexpr = (NullIfExpr *) node;
-				FuncExprState *fstate = makeNode(FuncExprState);
-
-				fstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalNullIf;
-				fstate->args = (List *)
-					ExecInitExpr((Expr *) nullifexpr->args, parent);
-				fstate->func.fn_oid = InvalidOid;		/* not initialized */
-				state = (ExprState *) fstate;
-			}
-			break;
 		case T_NullTest:
 			{
 				NullTest   *ntest = (NullTest *) node;