Here's version 2 of the patch, mainly to silence compiler warnings
about missing "case" statements from a switch over SubLinkType enum.
Also expanded commit message a little and changed whitespace to be
more consistent with nearby code.
Regards,
Marti
From 9f987efacfe2cd2af82722775127605e690df976 Mon Sep 17 00:00:00 2001
From: Marti Raudsepp <ma...@juffo.org>
Date: Tue, 6 Sep 2011 21:17:54 +0300
Subject: [PATCH] Generate column names for subquery expressions instead of
"?column?"
Previously these select expressions didn't have column names:
select (SELECT colname FROM tab) => colname
select (SELECT 1 AS foo) => foo
select exists(SELECT 1) => exists
select array(SELECT 1) => array
This change makes the subquery column name take precedence over "weak"
column names. Previously these two would return "int4" and "case", now
they return "foo":
select (select 1 foo)::int
select case when true then 1 else (select 1 as foo) end
---
src/backend/parser/parse_target.c | 33 ++++++++++++++++++++++++++++++
src/test/regress/expected/aggregates.out | 6 ++--
src/test/regress/expected/subselect.out | 12 +++++-----
src/test/regress/expected/with.out | 4 +-
4 files changed, 44 insertions(+), 11 deletions(-)
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 9d4e580..685233c 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -1585,6 +1585,39 @@ FigureColnameInternal(Node *node, char **name)
return FigureColnameInternal(ind->arg, name);
}
break;
+ case T_SubLink:
+ switch (((SubLink *) node)->subLinkType)
+ {
+ case EXISTS_SUBLINK:
+ *name = "exists";
+ return 2;
+ case ARRAY_SUBLINK:
+ *name = "array";
+ return 2;
+ case EXPR_SUBLINK:
+ /* Get column name from the subquery's target list */
+ {
+ SubLink *sublink = (SubLink *) node;
+ Query *query = (Query *) sublink->subselect;
+ /* EXPR_SUBLINK always has a single target */
+ TargetEntry *te = (TargetEntry *) linitial(query->targetList);
+
+ /* Subqueries have already been transformed */
+ if(te->resname)
+ {
+ *name = te->resname;
+ return 2;
+ }
+ }
+ break;
+ /* As with other operator-like nodes, these don't really have names */
+ case ALL_SUBLINK:
+ case ANY_SUBLINK:
+ case ROWCOMPARE_SUBLINK:
+ case CTE_SUBLINK:
+ break;
+ }
+ break;
case T_FuncCall:
*name = strVal(llast(((FuncCall *) node)->funcname));
return 2;
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 4861006..69926f7 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -300,9 +300,9 @@ LINE 4: where sum(distinct a.four + b.four) = b.four)...
select
(select max((select i.unique2 from tenk1 i where i.unique1 = o.unique1)))
from tenk1 o;
- ?column?
-----------
- 9999
+ max
+------
+ 9999
(1 row)
--
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index e638f0a..4ea8211 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -490,20 +490,20 @@ select view_a from view_a;
(1 row)
select (select view_a) from view_a;
- ?column?
-----------
+ view_a
+--------
(42)
(1 row)
select (select (select view_a)) from view_a;
- ?column?
-----------
+ view_a
+--------
(42)
(1 row)
select (select (a.*)::text) from view_a a;
- ?column?
-----------
+ a
+------
(42)
(1 row)
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index a1b0899..c4b0456 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -1065,7 +1065,7 @@ with cte(foo) as ( select 42 ) select * from ((select foo from cte)) q;
select ( with cte(foo) as ( values(f1) )
select (select foo from cte) )
from int4_tbl;
- ?column?
+ foo
-------------
0
123456
@@ -1077,7 +1077,7 @@ from int4_tbl;
select ( with cte(foo) as ( values(f1) )
values((select foo from cte)) )
from int4_tbl;
- ?column?
+ column1
-------------
0
123456
--
1.7.6.1
--
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