Fix subtly-wrong volatility checking in BeginCopyFrom().

tglsfdc · tglsfdc · commit 733e49ecff05 · 2013-11-08T08:59:49.000-05:00
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
@@ -2321,18 +2321,22 @@ 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
`@@ -2321,18 +2321,22 @@ BeginCopyFrom(Relation rel,`
`2321`	`2321`	`{`
`2322`	`2322`	`/* attribute is NOT to be copied from input */`
`2323`	`2323`	`/* use default value if one exists */`
`2324`		`- Node *defexpr = build_column_default(cstate->rel, attnum);`
	`2324`	`+ Expr defexpr = (Expr ) build_column_default(cstate->rel,`
	`2325`	`+ attnum);`
`2325`	`2326`
`2326`	`2327`	`if (defexpr != NULL)`
`2327`	`2328`	`{`
`2328`		`- /* Initialize expressions in copycontext. */`
`2329`		`- defexprs[num_defaults] = ExecInitExpr(`
`2330`		`- expression_planner((Expr *) defexpr), NULL);`
	`2329`	`+ /* Run the expression through planner */`
	`2330`	`+ defexpr = expression_planner(defexpr);`
	`2331`	`+`
	`2332`	`+ /* Initialize executable expression in copycontext */`
	`2333`	`+ defexprs[num_defaults] = ExecInitExpr(defexpr, NULL);`
`2331`	`2334`	`defmap[num_defaults] = attnum - 1;`
`2332`	`2335`	`num_defaults++;`
`2333`	`2336`
	`2337`	`+ /* Check to see if we have any volatile expressions */`
`2334`	`2338`	`if (!volatile_defexprs)`
`2335`		`- volatile_defexprs = contain_volatile_functions(defexpr);`
	`2339`	`+ volatile_defexprs = contain_volatile_functions((Node *) defexpr);`
`2336`	`2340`	`}`
`2337`	`2341`	`}`
`2338`	`2342`	`}`