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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