Reimplement CASE val WHEN compval1 THEN ... WHEN compval2 THEN ... END

so that the 'val' is computed only once, per recent discussion.  The
speedup is not much when 'val' is just a simple variable, but could be
significant for larger expressions.  More importantly this avoids issues
with multiple evaluations of a volatile 'val', and it allows the CASE
expression to be reverse-listed in its original form by ruleutils.c.

4 files changed, 61 insertions, 4 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index c1c4ddfed8b..c7d6193280e 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.278 2004/03/11 01:47:35 ishii Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.279 2004/03/17 20:48:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -969,6 +969,20 @@ _copyCaseWhen(CaseWhen *from)
 }
 
 /*
+ * _copyCaseTestExpr
+ */
+static CaseTestExpr *
+_copyCaseTestExpr(CaseTestExpr *from)
+{
+	CaseTestExpr *newnode = makeNode(CaseTestExpr);
+
+	COPY_SCALAR_FIELD(typeId);
+	COPY_SCALAR_FIELD(typeMod);
+
+	return newnode;
+}
+
+/*
  * _copyArrayExpr
  */
 static ArrayExpr *
@@ -2643,6 +2657,9 @@ copyObject(void *from)
 		case T_CaseWhen:
 			retval = _copyCaseWhen(from);
 			break;
+		case T_CaseTestExpr:
+			retval = _copyCaseTestExpr(from);
+			break;
 		case T_ArrayExpr:
 			retval = _copyArrayExpr(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index fadd02c9357..900d98dc8c0 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.217 2004/03/14 23:41:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.218 2004/03/17 20:48:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -404,6 +404,15 @@ _equalCaseWhen(CaseWhen *a, CaseWhen *b)
 }
 
 static bool
+_equalCaseTestExpr(CaseTestExpr *a, CaseTestExpr *b)
+{
+	COMPARE_SCALAR_FIELD(typeId);
+	COMPARE_SCALAR_FIELD(typeMod);
+
+	return true;
+}
+
+static bool
 _equalArrayExpr(ArrayExpr *a, ArrayExpr *b)
 {
 	COMPARE_SCALAR_FIELD(array_typeid);
@@ -1724,6 +1733,9 @@ equal(void *a, void *b)
 		case T_CaseWhen:
 			retval = _equalCaseWhen(a, b);
 			break;
+		case T_CaseTestExpr:
+			retval = _equalCaseTestExpr(a, b);
+			break;
 		case T_ArrayExpr:
 			retval = _equalArrayExpr(a, b);
 			break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 93afd868f87..4db6517cd76 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.232 2004/01/31 05:09:40 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.233 2004/03/17 20:48:42 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -806,6 +806,15 @@ _outCaseWhen(StringInfo str, CaseWhen *node)
 }
 
 static void
+_outCaseTestExpr(StringInfo str, CaseTestExpr *node)
+{
+	WRITE_NODE_TYPE("CASETESTEXPR");
+
+	WRITE_OID_FIELD(typeId);
+	WRITE_INT_FIELD(typeMod);
+}
+
+static void
 _outArrayExpr(StringInfo str, ArrayExpr *node)
 {
 	WRITE_NODE_TYPE("ARRAY");
@@ -1701,6 +1710,9 @@ _outNode(StringInfo str, void *obj)
 			case T_CaseWhen:
 				_outCaseWhen(str, obj);
 				break;
+			case T_CaseTestExpr:
+				_outCaseTestExpr(str, obj);
+				break;
 			case T_ArrayExpr:
 				_outArrayExpr(str, obj);
 				break;
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 93c71fd2247..116345686bf 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.165 2004/01/14 23:01:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.166 2004/03/17 20:48:42 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -649,6 +649,20 @@ _readCaseWhen(void)
 }
 
 /*
+ * _readCaseTestExpr
+ */
+static CaseTestExpr *
+_readCaseTestExpr(void)
+{
+	READ_LOCALS(CaseTestExpr);
+
+	READ_OID_FIELD(typeId);
+	READ_INT_FIELD(typeMod);
+
+	READ_DONE();
+}
+
+/*
  * _readArrayExpr
  */
 static ArrayExpr *
@@ -1010,6 +1024,8 @@ parseNodeString(void)
 		return_value = _readCaseExpr();
 	else if (MATCH("WHEN", 4))
 		return_value = _readCaseWhen();
+	else if (MATCH("CASETESTEXPR", 12))
+		return_value = _readCaseTestExpr();
 	else if (MATCH("ARRAY", 5))
 		return_value = _readArrayExpr();
 	else if (MATCH("COALESCE", 8))