From ad3e61b2809e5fc0133ca5bc6dde7450f85a00c1 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 12 Jun 2019 19:42:39 -0400
Subject: [PATCH] Fix incorrect printing of queries with duplicated join names.
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Given a query in which multiple JOIN nodes used the same alias
(which'd necessarily be in different sub-SELECTs), ruleutils.c
would assign the JOIN nodes distinct aliases for clarity ...
but then it forgot to print the modified aliases when dumping
the JOIN nodes themselves. This results in a dump/reload hazard
for views, because the emitted query is flat-out incorrect:
Vars will be printed with table names that have no referent.
This has been wrong for a long time, so back-patch to all supported
branches.
Philip Dubé
Discussion: https://postgr.es/m/CY4PR2101MB080246F2955FF58A6ED1FEAC98140@CY4PR2101MB0802.namprd21.prod.outlook.com
---
src/backend/utils/adt/ruleutils.c | 10 ++++++-
src/test/regress/expected/create_view.out | 35 +++++++++++++++++++++++
src/test/regress/sql/create_view.sql | 9 ++++++
3 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index c968213b8f9..f6f2b7c529d 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9501,8 +9501,16 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
/* Yes, it's correct to put alias after the right paren ... */
if (j->alias != NULL)
{
+ /*
+ * Note that it's correct to emit an alias clause if and only if
+ * there was one originally. Otherwise we'd be converting a named
+ * join to unnamed or vice versa, which creates semantic
+ * subtleties we don't want. However, we might print a different
+ * alias name than was there originally.
+ */
appendStringInfo(buf, " %s",
- quote_identifier(j->alias->aliasname));
+ quote_identifier(get_rtable_name(j->rtindex,
+ context)));
get_column_alias_list(colinfo, context);
}
}
diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out
index 1434c2f85aa..63299043caf 100644
--- a/src/test/regress/expected/create_view.out
+++ b/src/test/regress/expected/create_view.out
@@ -743,6 +743,41 @@ View definition:
FROM temp_view_test.tx1 tx1_1
WHERE tx1.y1 = tx1_1.f1));
+-- Test aliasing of joins
+create view view_of_joins as
+select * from
+ (select * from (tbl1 cross join tbl2) same) ss,
+ (tbl3 cross join tbl4) same;
+\d+ view_of_joins
+ View "testviewschm2.view_of_joins"
+ Column | Type | Modifiers | Storage | Description
+--------+---------+-----------+---------+-------------
+ a | integer | | plain |
+ b | integer | | plain |
+ c | integer | | plain |
+ d | integer | | plain |
+ e | integer | | plain |
+ f | integer | | plain |
+ g | integer | | plain |
+ h | integer | | plain |
+View definition:
+ SELECT ss.a,
+ ss.b,
+ ss.c,
+ ss.d,
+ same.e,
+ same.f,
+ same.g,
+ same.h
+ FROM ( SELECT same_1.a,
+ same_1.b,
+ same_1.c,
+ same_1.d
+ FROM (tbl1
+ CROSS JOIN tbl2) same_1) ss,
+ (tbl3
+ CROSS JOIN tbl4) same;
+
-- Test view decompilation in the face of column addition/deletion/renaming
create table tt2 (a int, b int, c int);
create table tt3 (ax int8, b int2, c numeric);
diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql
index 11f539fcd36..840c43b577e 100644
--- a/src/test/regress/sql/create_view.sql
+++ b/src/test/regress/sql/create_view.sql
@@ -311,6 +311,15 @@ ALTER TABLE tmp1 RENAME TO tx1;
\d+ aliased_view_3
\d+ aliased_view_4
+-- Test aliasing of joins
+
+create view view_of_joins as
+select * from
+ (select * from (tbl1 cross join tbl2) same) ss,
+ (tbl3 cross join tbl4) same;
+
+\d+ view_of_joins
+
-- Test view decompilation in the face of column addition/deletion/renaming
create table tt2 (a int, b int, c int);
--
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