Fix subtly-wrong volatility checking in BeginCopyFrom().

tglsfdc · tglsfdc · commit 060b22a99a67 · 2013-11-08T08:59:39.000-05:00
contain_volatile_functions() is best applied to the output of
expression_planner(), not its input, so that insertion of function
default arguments and constant-folding have been done.  (See comments
at CheckMutability, for instance.)  It's perhaps unlikely that anyone
will notice a difference in practice, but still we should do it properly.

In passing, change variable type from Node* to Expr* to reduce the net
number of casts needed.

Noted while perusing uses of contain_volatile_functions().
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
@@ -2506,18 +2506,22 @@ BeginCopyFrom(Relation rel,
 		{
 			/* attribute is NOT to be copied from input */
 			/* use default value if one exists */
-			Node	   *defexpr = build_column_default(cstate->rel, attnum);
+			Expr	   *defexpr = (Expr *) build_column_default(cstate->rel,
+																attnum);
 
 			if (defexpr != NULL)
 			{
-				/* Initialize expressions in copycontext. */
-				defexprs[num_defaults] = ExecInitExpr(
-								 expression_planner((Expr *) defexpr), NULL);
+				/* Run the expression through planner */
+				defexpr = expression_planner(defexpr);
+
+				/* Initialize executable expression in copycontext */
+				defexprs[num_defaults] = ExecInitExpr(defexpr, NULL);
 				defmap[num_defaults] = attnum - 1;
 				num_defaults++;
 
+				/* Check to see if we have any volatile expressions */
 				if (!volatile_defexprs)
-					volatile_defexprs = contain_volatile_functions(defexpr);
+					volatile_defexprs = contain_volatile_functions((Node *) defexpr);
 			}
 		}
 	}

Original file line number	Diff line number	Diff line change
`@@ -2506,18 +2506,22 @@ BeginCopyFrom(Relation rel,`
`2506`	`2506`	`{`
`2507`	`2507`	`/* attribute is NOT to be copied from input */`
`2508`	`2508`	`/* use default value if one exists */`
`2509`		`- Node *defexpr = build_column_default(cstate->rel, attnum);`
	`2509`	`+ Expr defexpr = (Expr ) build_column_default(cstate->rel,`
	`2510`	`+ attnum);`
`2510`	`2511`
`2511`	`2512`	`if (defexpr != NULL)`
`2512`	`2513`	`{`
`2513`		`- /* Initialize expressions in copycontext. */`
`2514`		`- defexprs[num_defaults] = ExecInitExpr(`
`2515`		`- expression_planner((Expr *) defexpr), NULL);`
	`2514`	`+ /* Run the expression through planner */`
	`2515`	`+ defexpr = expression_planner(defexpr);`
	`2516`	`+`
	`2517`	`+ /* Initialize executable expression in copycontext */`
	`2518`	`+ defexprs[num_defaults] = ExecInitExpr(defexpr, NULL);`
`2516`	`2519`	`defmap[num_defaults] = attnum - 1;`
`2517`	`2520`	`num_defaults++;`
`2518`	`2521`
	`2522`	`+ /* Check to see if we have any volatile expressions */`
`2519`	`2523`	`if (!volatile_defexprs)`
`2520`		`- volatile_defexprs = contain_volatile_functions(defexpr);`
	`2524`	`+ volatile_defexprs = contain_volatile_functions((Node *) defexpr);`
`2521`	`2525`	`}`
`2522`	`2526`	`}`
`2523`	`2527`	`}`