Fix dumping of views that are just VALUES(...) but have column aliases.

tglsfdc · tglsfdc · commit f7b41902a673 · 2015-02-25T12:01:12.000-05:00
The "simple" path for printing VALUES clauses doesn't work if we need to attach nondefault column aliases, because there's noplace to do that in the minimal VALUES() syntax. So modify get_simple_values_rte() to detect nondefault aliases and treat that as a non-simple case. This further exposes that the "non-simple" path never actually worked; it didn't produce valid syntax. Fix that too. Per bug #12789 from Curtis McEnroe, and analysis by Andrew Gierth. Back-patch to all supported branches. Before 9.3, this also requires back-patching the part of commit 092d7de that created get_simple_values_rte() to begin with; inserting the extra test into the old factorization of that logic would've been too messy.
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
@@ -2878,11 +2878,72 @@ get_select_query_def(Query *query, deparse_context *context,
 	context->windowTList = save_windowtlist;
 }
 
+/*
+ * Detect whether query looks like SELECT ... FROM VALUES();
+ * if so, return the VALUES RTE.  Otherwise return NULL.
+ */
+static RangeTblEntry *
+get_simple_values_rte(Query *query)
+{
+	RangeTblEntry *result = NULL;
+	ListCell   *lc;
+
+	/*
+	 * We want to return TRUE even if the Query also contains OLD or NEW rule
+	 * RTEs.  So the idea is to scan the rtable and see if there is only one
+	 * inFromCl RTE that is a VALUES RTE.
+	 */
+	foreach(lc, query->rtable)
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
+
+		if (rte->rtekind == RTE_VALUES && rte->inFromCl)
+		{
+			if (result)
+				return NULL;	/* multiple VALUES (probably not possible) */
+			result = rte;
+		}
+		else if (rte->rtekind == RTE_RELATION && !rte->inFromCl)
+			continue;			/* ignore rule entries */
+		else
+			return NULL;		/* something else -> not simple VALUES */
+	}
+
+	/*
+	 * We don't need to check the targetlist in any great detail, because
+	 * parser/analyze.c will never generate a "bare" VALUES RTE --- they only
+	 * appear inside auto-generated sub-queries with very restricted
+	 * structure.  However, DefineView might have modified the tlist by
+	 * injecting new column aliases; so compare tlist resnames against the
+	 * RTE's names to detect that.
+	 */
+	if (result)
+	{
+		ListCell   *lcn;
+
+		if (list_length(query->targetList) != list_length(result->eref->colnames))
+			return NULL;		/* this probably cannot happen */
+		forboth(lc, query->targetList, lcn, result->eref->colnames)
+		{
+			TargetEntry *tle = (TargetEntry *) lfirst(lc);
+			char	   *cname = strVal(lfirst(lcn));
+
+			if (tle->resjunk)
+				return NULL;	/* this probably cannot happen */
+			if (tle->resname == NULL || strcmp(tle->resname, cname) != 0)
+				return NULL;	/* column name has been changed */
+		}
+	}
+
+	return result;
+}
+
 static void
 get_basic_select_query(Query *query, deparse_context *context,
 					   TupleDesc resultDesc)
 {
 	StringInfo	buf = context->buf;
+	RangeTblEntry *values_rte;
 	char	   *sep;
 	ListCell   *l;
 
@@ -2895,23 +2956,13 @@ get_basic_select_query(Query *query, deparse_context *context,
 	/*
 	 * If the query looks like SELECT * FROM (VALUES ...), then print just the
 	 * VALUES part.  This reverses what transformValuesClause() did at parse
-	 * time.  If the jointree contains just a single VALUES RTE, we assume
-	 * this case applies (without looking at the targetlist...)
+	 * time.
 	 */
-	if (list_length(query->jointree->fromlist) == 1)
+	values_rte = get_simple_values_rte(query);
+	if (values_rte)
 	{
-		RangeTblRef *rtr = (RangeTblRef *) linitial(query->jointree->fromlist);
-
-		if (IsA(rtr, RangeTblRef))
-		{
-			RangeTblEntry *rte = rt_fetch(rtr->rtindex, query->rtable);
-
-			if (rte->rtekind == RTE_VALUES)
-			{
-				get_values_def(rte->values_lists, context);
-				return;
-			}
-		}
+		get_values_def(values_rte->values_lists, context);
+		return;
 	}
 
 	/*
@@ -6474,7 +6525,9 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 				break;
 			case RTE_VALUES:
 				/* Values list RTE */
+				appendStringInfoChar(buf, '(');
 				get_values_def(rte->values_lists, context);
+				appendStringInfoChar(buf, ')');
 				break;
 			case RTE_CTE:
 				appendStringInfoString(buf, quote_identifier(rte->ctename));
@@ -6514,6 +6567,13 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 							 quote_identifier(rte->eref->aliasname));
 			gavealias = true;
 		}
+		else if (rte->rtekind == RTE_VALUES)
+		{
+			/* Alias is syntactically required for VALUES */
+			appendStringInfo(buf, " %s",
+							 quote_identifier(rte->eref->aliasname));
+			gavealias = true;
+		}
 
 		if (rte->rtekind == RTE_FUNCTION)
 		{
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
@@ -1590,3 +1590,54 @@ select * from only t1_2;
  19
 (10 rows)
 
+reset constraint_exclusion;
+--
+-- check display of VALUES in view definitions
+--
+create view rule_v1 as values(1,2);
+\d+ rule_v1
+                 View "public.rule_v1"
+ Column  |  Type   | Modifiers | Storage | Description 
+---------+---------+-----------+---------+-------------
+ column1 | integer |           | plain   | 
+ column2 | integer |           | plain   | 
+View definition:
+ VALUES (1,2);
+
+drop view rule_v1;
+create view rule_v1(x) as values(1,2);
+\d+ rule_v1
+                 View "public.rule_v1"
+ Column  |  Type   | Modifiers | Storage | Description 
+---------+---------+-----------+---------+-------------
+ x       | integer |           | plain   | 
+ column2 | integer |           | plain   | 
+View definition:
+ SELECT "*VALUES*".column1 AS x, "*VALUES*".column2
+   FROM (VALUES (1,2)) "*VALUES*";
+
+drop view rule_v1;
+create view rule_v1(x) as select * from (values(1,2)) v;
+\d+ rule_v1
+                 View "public.rule_v1"
+ Column  |  Type   | Modifiers | Storage | Description 
+---------+---------+-----------+---------+-------------
+ x       | integer |           | plain   | 
+ column2 | integer |           | plain   | 
+View definition:
+ SELECT v.column1 AS x, v.column2
+   FROM ( VALUES (1,2)) v;
+
+drop view rule_v1;
+create view rule_v1(x) as select * from (values(1,2)) v(q,w);
+\d+ rule_v1
+                View "public.rule_v1"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ x      | integer |           | plain   | 
+ w      | integer |           | plain   | 
+View definition:
+ SELECT v.q AS x, v.w
+   FROM ( VALUES (1,2)) v(q, w);
+
+drop view rule_v1;
diff --git a/src/test/regress/sql/rules.sql b/src/test/regress/sql/rules.sql
@@ -942,3 +942,21 @@ update t1 set a = 4 where a = 5;
 select * from only t1;
 select * from only t1_1;
 select * from only t1_2;
+
+reset constraint_exclusion;
+
+--
+-- check display of VALUES in view definitions
+--
+create view rule_v1 as values(1,2);
+\d+ rule_v1
+drop view rule_v1;
+create view rule_v1(x) as values(1,2);
+\d+ rule_v1
+drop view rule_v1;
+create view rule_v1(x) as select * from (values(1,2)) v;
+\d+ rule_v1
+drop view rule_v1;
+create view rule_v1(x) as select * from (values(1,2)) v(q,w);
+\d+ rule_v1
+drop view rule_v1;
