Fix problem in which sloppily-coded test in ExecInitIndexScan would

think that both sides of indexqual look like index keys.  An example is
create table inside (f1 float8 primary key);
create table outside (g1 float8, g2 float8);
select * from inside,outside where f1 = atan2(g1+1, g2);
ERROR:  ExecInitIndexScan: both left and right ops are rel-vars
(note that failure is potentially platform-dependent).  Solution is a
cleanup I had had in mind to make anyway: functional index keys should
be represented as Var nodes in the fixed indexqual, just like regular
index keys.

src/backend/executor/nodeIndexscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.49 2000/04/12 17:15:09 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.50 2000/05/23 16:56:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -734,8 +734,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 		 */
 		for (j = 0; j < n_keys; j++)
 		{
-			Expr	   *clause; /* one part of index qual */
-			Oper	   *op;		/* operator used in scan.. */
+			Expr	   *clause; /* one clause of index qual */
+			Oper	   *op;		/* operator used in clause */
 			Node	   *leftop; /* expr on lhs of operator */
 			Node	   *rightop;/* expr on rhs ... */
 			bits16		flags = 0;
@@ -794,6 +794,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 			 */
 
 			scanvar = NO_OP;
+			run_keys[j] = NO_OP;
 
 			/* ----------------
 			 *	determine information in leftop
@@ -803,7 +804,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 
 			Assert(leftop != NULL);
 
-			if (IsA(leftop, Var) &&var_is_rel((Var *) leftop))
+			if (IsA(leftop, Var) && var_is_rel((Var *) leftop))
 			{
 				/* ----------------
 				 *	if the leftop is a "rel-var", then it means
@@ -814,19 +815,6 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				varattno = ((Var *) leftop)->varattno;
 				scanvar = LEFT_OP;
 			}
-			else if (is_funcclause(leftop) &&
-					 var_is_rel(lfirst(((Expr *) leftop)->args)))
-			{
-				/* ----------------
-				 *	if the leftop is a func node then it means
-				 *	it identifies the value to place in our scan key.
-				 *	Since functional indices have only one attribute
-				 *	the attno must always be set to 1.
-				 * ----------------
-				 */
-				varattno = 1;
-				scanvar = LEFT_OP;
-			}
 			else if (IsA(leftop, Const))
 			{
 				/* ----------------
@@ -834,8 +822,9 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				 *	it identifies the value to place in our scan key.
 				 * ----------------
 				 */
-				run_keys[j] = NO_OP;
 				scanvalue = ((Const *) leftop)->constvalue;
+				if (((Const *) leftop)->constisnull)
+					flags |= SK_ISNULL;
 			}
 			else if (IsA(leftop, Param))
 			{
@@ -850,32 +839,31 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				/* Life was so easy before ... subselects */
 				if (((Param *) leftop)->paramkind == PARAM_EXEC)
 				{
+					/* treat Param as runtime key */
 					have_runtime_keys = true;
 					run_keys[j] = LEFT_OP;
 					execParam = lappendi(execParam, ((Param *) leftop)->paramid);
 				}
 				else
 				{
+					/* treat Param like a constant */
 					scanvalue = ExecEvalParam((Param *) leftop,
 										scanstate->cstate.cs_ExprContext,
 											  &isnull);
 					if (isnull)
 						flags |= SK_ISNULL;
-
-					run_keys[j] = NO_OP;
 				}
 			}
 			else
 			{
 				/* ----------------
-				 *	otherwise, the leftop contains information usable
+				 *	otherwise, the leftop contains an expression evaluable
 				 *	at runtime to figure out the value to place in our
 				 *	scan key.
 				 * ----------------
 				 */
 				have_runtime_keys = true;
 				run_keys[j] = LEFT_OP;
-				scanvalue = Int32GetDatum((int32) true);
 			}
 
 			/* ----------------
@@ -886,7 +874,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 
 			Assert(rightop != NULL);
 
-			if (IsA(rightop, Var) &&var_is_rel((Var *) rightop))
+			if (IsA(rightop, Var) && var_is_rel((Var *) rightop))
 			{
 				/* ----------------
 				 *	here we make sure only one op identifies the
@@ -906,23 +894,6 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				varattno = ((Var *) rightop)->varattno;
 				scanvar = RIGHT_OP;
 			}
-			else if (is_funcclause(rightop) &&
-					 var_is_rel(lfirst(((Expr *) rightop)->args)))
-			{
-				/* ----------------
-				 *	if the rightop is a func node then it means
-				 *	it identifies the value to place in our scan key.
-				 *	Since functional indices have only one attribute
-				 *	the attno must always be set to 1.
-				 * ----------------
-				 */
-				if (scanvar == LEFT_OP)
-					elog(ERROR, "ExecInitIndexScan: %s",
-						 "both left and right ops are rel-vars");
-
-				varattno = 1;
-				scanvar = RIGHT_OP;
-			}
 			else if (IsA(rightop, Const))
 			{
 				/* ----------------
@@ -930,8 +901,9 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				 *	it identifies the value to place in our scan key.
 				 * ----------------
 				 */
-				run_keys[j] = NO_OP;
 				scanvalue = ((Const *) rightop)->constvalue;
+				if (((Const *) rightop)->constisnull)
+					flags |= SK_ISNULL;
 			}
 			else if (IsA(rightop, Param))
 			{
@@ -946,32 +918,31 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 				/* Life was so easy before ... subselects */
 				if (((Param *) rightop)->paramkind == PARAM_EXEC)
 				{
+					/* treat Param as runtime key */
 					have_runtime_keys = true;
 					run_keys[j] = RIGHT_OP;
 					execParam = lappendi(execParam, ((Param *) rightop)->paramid);
 				}
 				else
 				{
+					/* treat Param like a constant */
 					scanvalue = ExecEvalParam((Param *) rightop,
 										scanstate->cstate.cs_ExprContext,
 											  &isnull);
 					if (isnull)
 						flags |= SK_ISNULL;
-
-					run_keys[j] = NO_OP;
 				}
 			}
 			else
 			{
 				/* ----------------
-				 *	otherwise, the rightop contains information usable
+				 *	otherwise, the rightop contains an expression evaluable
 				 *	at runtime to figure out the value to place in our
 				 *	scan key.
 				 * ----------------
 				 */
 				have_runtime_keys = true;
 				run_keys[j] = RIGHT_OP;
-				scanvalue = Int32GetDatum((int32) true);
 			}
 
 			/* ----------------
@@ -992,7 +963,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 								   varattno,	/* attribute number to
 												 * scan */
 								   (RegProcedure) opid, /* reg proc to use */
-								   (Datum) scanvalue);	/* constant */
+								   scanvalue);	/* constant */
 		}
 
 		/* ----------------

src/backend/optimizer/plan/createplan.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.89 2000/04/12 17:15:21 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.90 2000/05/23 16:56:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -27,6 +27,7 @@
 #include "optimizer/planmain.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/tlist.h"
+#include "parser/parse_expr.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 
@@ -722,7 +723,7 @@ create_hashjoin_node(HashPath *best_path,
  *	  machinery needs.
  *
  * We have three tasks here:
- *	* Var nodes representing index keys must have varattno equal to the
+ *	* Index keys must be represented by Var nodes with varattno set to the
  *	  index's attribute number, not the attribute number in the original rel.
  *	* indxpath.c may have selected an index that is binary-compatible with
  *	  the actual expression operator, but not exactly the same datatype.
@@ -789,7 +790,7 @@ fix_indxqual_references(List *indexquals, IndexPath *index_path)
  * Fix the sublist of indexquals to be used in a particular scan.
  *
  * For each qual clause, commute if needed to put the indexkey operand on the
- * left, and then change its varno.  (We do not need to change the other side
+ * left, and then fix its varattno.  (We do not need to change the other side
  * of the clause.)	Also change the operator if necessary.
  */
 static List *
@@ -863,8 +864,16 @@ static Node *
 fix_indxqual_operand(Node *node, int baserelid, Form_pg_index index,
 					 Oid *opclass)
 {
+	/*
+	 * We represent index keys by Var nodes having the varno of the base
+	 * table but varattno equal to the index's attribute number (index
+	 * column position).  This is a bit hokey ... would be cleaner to use
+	 * a special-purpose node type that could not be mistaken for a regular
+	 * Var.  But it will do for now.
+	 */
 	if (IsA(node, Var))
 	{
+		/* If it's a var, find which index key position it occupies */
 		if (((Var *) node)->varno == baserelid)
 		{
 			int			varatt = ((Var *) node)->varattno;
@@ -877,6 +886,7 @@ fix_indxqual_operand(Node *node, int baserelid, Form_pg_index index,
 					Node	   *newnode = copyObject(node);
 
 					((Var *) newnode)->varattno = pos + 1;
+					/* return the correct opclass, too */
 					*opclass = index->indclass[pos];
 					return newnode;
 				}
@@ -890,22 +900,17 @@ fix_indxqual_operand(Node *node, int baserelid, Form_pg_index index,
 	}
 
 	/*
-	 * Else, it must be a func expression representing a functional index.
-	 *
-	 * Currently, there is no need for us to do anything here for functional
-	 * indexes.  If nodeIndexscan.c sees a func clause as the left or
-	 * right-hand toplevel operand of an indexqual, it assumes that that
-	 * is a reference to the functional index's value and makes the
-	 * appropriate substitution.  (It would be cleaner to make the
-	 * substitution here, I think --- suspect this issue if a join clause
-	 * involving a function call misbehaves...)
+	 * Else, it must be a func expression matching a functional index.
+	 * Since we currently only support single-column functional indexes,
+	 * the returned varattno must be 1.
 	 */
 
+	Assert(is_funcclause(node)); /* not a very thorough check, but easy */
+
 	/* indclass[0] is the only class of a functional index */
 	*opclass = index->indclass[0];
 
-	/* return the unmodified node */
-	return node;
+	return (Node *) makeVar(baserelid, 1, exprType(node), -1, 0);
 }
 
 /*