Fix normalization of NULL

src/pg_query_normalize.c

@@ -160,6 +160,11 @@ fill_in_constant_lengths(pgssConstLocations *jstate, const char *query)
 			if (tok == 0)
 				break;			/* out of inner for-loop */
 
+            /* Ignore NULL constants */
+            if (tok == NULL_P) {
+                continue;
+            }
+
 			/*
 			 * We should find the token position exactly, but if we somehow
 			 * run past it, work with that.
@@ -213,15 +218,7 @@ fill_in_constant_lengths(pgssConstLocations *jstate, const char *query)
 
 					locs[i].val = (char *)palloc(buf_size * sizeof(char));
 					snprintf(locs[i].val, buf_size, "%d", val);
-				}
-				else if (tok == NULL_P)
-				{
-					/*
-					 * Do not extract NULL literals as those mess with
-					 * Postgres type inference.
-					 */
-					locs[i].length = -1;
-				}
+				}				
 
 				break;			/* out of inner for-loop */
 			}
@@ -399,6 +396,15 @@ static bool const_record_walker(Node *node, pgssConstLocations *jstate)
 	switch (nodeTag(node))
 	{
 		case T_A_Const:
+
+            /*
+             * Do not extract NULL constants as those mess with
+             * Postgres type inference.
+             */
+            if (castNode(A_Const, node)->isnull) {
+                return false;
+            }
+
 			RecordConstLocation(jstate, castNode(A_Const, node)->location);
 			break;
 		case T_ParamRef:

test/normalize_tests.c

@@ -50,6 +50,8 @@ const char* tests[] = {
   "SELECT $1; ALTER USER a WITH PASSWORD 'b'",
   "SELECT U&'d!0061t!+000061' UESCAPE '!', -2147483647, -2147483648, x'beef', b'010101'",
   "SELECT $1, $2, $3, $4, $5",
+  "VALUES (1, NULL, 2)",
+  "VALUES ($1, NULL, $2)",
 };
 
 size_t testsLength = __LINE__ - 7;

test/normalize_utility_tests.c

@@ -49,6 +49,8 @@ const char* tests[] = {
   "CLOSE cursor_a",
   "SELECT 1; ALTER USER a WITH PASSWORD 'b'",
   "SELECT 1; ALTER USER a WITH PASSWORD $1",
+  "VALUES (1, NULL, 2)",
+  "VALUES (1, NULL, 2)",
 };
 
 size_t testsLength = __LINE__ - 8;