Reconsider old decision to try to constant-fold default and constraint

tglsfdc · tglsfdc · commit 2d140d35a417 · 2003-01-08T22:06:23.000Z
expressions before they are stored.  This seems like not such a hot idea,
particularly now that the constant-folder will try to inline SQL functions.
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.238 2002/12/16 18:39:22 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.239 2003/01/08 22:06:20 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1604,11 +1604,6 @@ AddRelationRawConstraints(Relation rel,
 		if (contain_agg_clause(expr))
 			elog(ERROR, "cannot use aggregate function in CHECK constraint expression");
 
-		/*
-		 * Might as well try to reduce any constant expressions.
-		 */
-		expr = eval_const_expressions(expr);
-
 		/*
 		 * Constraints are evaluated with execQual, which expects an
 		 * implicit-AND list, so convert expression to implicit-AND form.
@@ -1733,7 +1728,7 @@ cookDefault(ParseState *pstate,
 	 * column's type.  We store the expression without coercion, however,
 	 * to avoid premature coercion in cases like
 	 *
-	 * CREATE TABLE tbl (fld timestamp DEFAULT 'now'::text);
+	 * CREATE TABLE tbl (fld timestamp DEFAULT 'now');
 	 *
 	 * NB: this should match the code in rewrite/rewriteHandler.c that will
 	 * actually do the coercion, to ensure we don't accept an unusable
@@ -1755,11 +1750,6 @@ cookDefault(ParseState *pstate,
 				 format_type_be(type_id));
 	}
 
-	/*
-	 * Might as well try to reduce any constant expressions.
-	 */
-	expr = eval_const_expressions(expr);
-
 	return (expr);
 }
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.64 2002/12/30 19:45:17 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.65 2003/01/08 22:06:23 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2756,7 +2756,10 @@ AlterTableAddCheckConstraint(Relation rel, Constraint *constr)
 		elog(ERROR, "cannot use aggregate function in CHECK constraint expression");
 
 	/*
-	 * Might as well try to reduce any constant expressions.
+	 * Might as well try to reduce any constant expressions, so as to
+	 * minimize overhead while testing the constraint at each row.
+	 *
+	 * Note that the stored form of the constraint will NOT be const-folded.
 	 */
 	expr = eval_const_expressions(expr);
 
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/typecmds.c,v 1.28 2003/01/08 21:40:39 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/typecmds.c,v 1.29 2003/01/08 22:06:23 tgl Exp $
  *
  * DESCRIPTION
  *	  The "DefineFoo" routines take the parse tree and pick out the
@@ -1623,11 +1623,6 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
 	if (contain_agg_clause(expr))
 		elog(ERROR, "cannot use aggregate function in CHECK constraint expression");
 
-	/*
-	 * Might as well try to reduce any constant expressions.
-	 */
-	expr = eval_const_expressions(expr);
-
 	/*
 	 * Convert to string form for storage.
 	 */

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.238 2002/12/16 18:39:22 tgl Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.239 2003/01/08 22:06:20 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*`
`14`	`14`	`* INTERFACE ROUTINES`
`@@ -1604,11 +1604,6 @@ AddRelationRawConstraints(Relation rel,`
`1604`	`1604`	`if (contain_agg_clause(expr))`
`1605`	`1605`	`elog(ERROR, "cannot use aggregate function in CHECK constraint expression");`
`1606`	`1606`
`1607`		`- /*`
`1608`		`- * Might as well try to reduce any constant expressions.`
`1609`		`- */`
`1610`		`- expr = eval_const_expressions(expr);`
`1611`		`-`
`1612`	`1607`	`/*`
`1613`	`1608`	`* Constraints are evaluated with execQual, which expects an`
`1614`	`1609`	`* implicit-AND list, so convert expression to implicit-AND form.`
`@@ -1733,7 +1728,7 @@ cookDefault(ParseState *pstate,`
`1733`	`1728`	`* column's type. We store the expression without coercion, however,`
`1734`	`1729`	`* to avoid premature coercion in cases like`
`1735`	`1730`	`*`
`1736`		`- * CREATE TABLE tbl (fld timestamp DEFAULT 'now'::text);`
	`1731`	`+ * CREATE TABLE tbl (fld timestamp DEFAULT 'now');`
`1737`	`1732`	`*`
`1738`	`1733`	`* NB: this should match the code in rewrite/rewriteHandler.c that will`
`1739`	`1734`	`* actually do the coercion, to ensure we don't accept an unusable`
`@@ -1755,11 +1750,6 @@ cookDefault(ParseState *pstate,`
`1755`	`1750`	`format_type_be(type_id));`
`1756`	`1751`	`}`
`1757`	`1752`
`1758`		`- /*`
`1759`		`- * Might as well try to reduce any constant expressions.`
`1760`		`- */`
`1761`		`- expr = eval_const_expressions(expr);`
`1762`		`-`
`1763`	`1753`	`return (expr);`
`1764`	`1754`	`}`
`1765`	`1755`