diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 7be2f1b8c99a40f23929155a547fc513e061309b..362851a425a32280b39feee9ceba218a1c3b13ec 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.41 1999/08/09 06:20:22 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.42 1999/08/12 00:42:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -741,7 +741,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
/* ----------------
* Here we figure out the contents of the index qual.
- * The usual case is (op var const) or (op const var)
+ * The usual case is (var op const) or (const op var)
* which means we form a scan key for the attribute
* listed in the var node and use the value of the const.
*
@@ -759,6 +759,19 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
* Hence, we set have_runtime_keys to true and then set
* the appropriate flag in run_keys to LEFT_OP or RIGHT_OP.
* The corresponding scan keys are recomputed at run time.
+ *
+ * XXX Although this code *thinks* it can handle an indexqual
+ * with the indexkey on either side, in fact it cannot.
+ * Indexscans only work with quals that have the indexkey on
+ * the left (the planner/optimizer makes sure it never passes
+ * anything else). The reason: the scankey machinery has no
+ * provision for distinguishing which side of the operator is
+ * the indexed attribute and which is the compared-to constant.
+ * It just assumes that the attribute is on the left :-(
+ *
+ * I am leaving this code able to support both ways, even though
+ * half of it is dead code, on the off chance that someone will
+ * fix the scankey machinery someday --- tgl 8/11/99.
* ----------------
*/
@@ -770,7 +783,9 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
*/
leftop = (Node *) get_leftop(clause);
- if (IsA(leftop, Var) &&var_is_rel((Var *) leftop))
+ Assert(leftop != NULL);
+
+ if (IsA(leftop, Var) && var_is_rel((Var *) leftop))
{
/* ----------------
* if the leftop is a "rel-var", then it means
@@ -781,6 +796,19 @@ 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))
{
/* ----------------
@@ -819,21 +847,6 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
run_keys[j] = NO_OP;
}
}
- else if (leftop != NULL &&
- 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
{
/* ----------------
@@ -853,7 +866,9 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
*/
rightop = (Node *) get_rightop(clause);
- if (IsA(rightop, Var) &&var_is_rel((Var *) rightop))
+ Assert(rightop != NULL);
+
+ if (IsA(rightop, Var) && var_is_rel((Var *) rightop))
{
/* ----------------
* here we make sure only one op identifies the
@@ -872,12 +887,28 @@ 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))
{
/* ----------------
- * if the leftop is a const node then it means
+ * if the rightop is a const node then it means
* it identifies the value to place in our scan key.
* ----------------
*/
@@ -912,29 +943,10 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
run_keys[j] = NO_OP;
}
}
- else if (rightop != NULL &&
- 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
{
/* ----------------
- * otherwise, the leftop contains information usable
+ * otherwise, the rightop contains information usable
* at runtime to figure out the value to place in our
* scan key.
* ----------------