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postgres_fdw: When sending ORDER BY, always include NULLS FIRST/LAST.

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Previously, we included NULLS FIRST when appropriate but relied on the
default behavior to be NULLS LAST.  This is, however, not true for a
sort in descending order and seems like a fragile assumption anyway.

Report by Rajkumar Raghuwanshi.  Patch by Ashutosh Bapat.  Review
comments from Michael Paquier and Tom Lane.
pull/11/head
Robert Haas 10 years ago
parent 52fe6f4e02
commit 3bea3f88d5
3 changed files with 125 additions and 31 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 2
      contrib/postgres_fdw/deparse.c
  2. 142
      contrib/postgres_fdw/expected/postgres_fdw.out
  3. 12
      contrib/postgres_fdw/sql/postgres_fdw.sql

2
contrib/postgres_fdw/deparse.c
Unescape View File

@ -2308,6 +2308,8 @@ appendOrderByClause(List *pathkeys, deparse_expr_cxt *context)
if (pathkey->pk_nulls_first)
appendStringInfoString(buf, " NULLS FIRST");
else
appendStringInfoString(buf, " NULLS LAST");
delim = ", ";
}

142
contrib/postgres_fdw/expected/postgres_fdw.out
Unescape View File

@ -245,13 +245,13 @@ SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1, t1.tableoid OFFSET 100 LIMIT 10;
-- whole-row reference
EXPLAIN (VERBOSE, COSTS false) SELECT t1 FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------------------------------------
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------
Limit
Output: t1.*, c3, c1
-> Foreign Scan on public.ft1 t1
Output: t1.*, c3, c1
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY c3 ASC, "C 1" ASC
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY c3 ASC NULLS LAST, "C 1" ASC NULLS LAST
(5 rows)
SELECT t1 FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
@ -382,8 +382,8 @@ SET enable_nestloop TO false;
-- inner join; expressions in the clauses appear in the equivalence class list
EXPLAIN (VERBOSE, COSTS false)
SELECT t1.c1, t2."C 1" FROM ft2 t1 JOIN "S 1"."T 1" t2 ON (t1.c1 = t2."C 1") OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2."C 1"
-> Merge Join
@ -391,7 +391,7 @@ EXPLAIN (VERBOSE, COSTS false)
Merge Cond: (t1.c1 = t2."C 1")
-> Foreign Scan on public.ft2 t1
Output: t1.c1
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
-> Index Only Scan using t1_pkey on "S 1"."T 1" t2
Output: t2."C 1"
(10 rows)
@ -415,8 +415,8 @@ SELECT t1.c1, t2."C 1" FROM ft2 t1 JOIN "S 1"."T 1" t2 ON (t1.c1 = t2."C 1") OFF
-- list but no output change as compared to the previous query
EXPLAIN (VERBOSE, COSTS false)
SELECT t1.c1, t2."C 1" FROM ft2 t1 LEFT JOIN "S 1"."T 1" t2 ON (t1.c1 = t2."C 1") OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2."C 1"
-> Merge Left Join
@ -424,7 +424,7 @@ EXPLAIN (VERBOSE, COSTS false)
Merge Cond: (t1.c1 = t2."C 1")
-> Foreign Scan on public.ft2 t1
Output: t1.c1
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
-> Index Only Scan using t1_pkey on "S 1"."T 1" t2
Output: t2."C 1"
(10 rows)
@ -1341,8 +1341,8 @@ SELECT t1.ctid, t1, t2, t1.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER B
-- SEMI JOIN, not pushed down
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1 FROM ft1 t1 WHERE EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c1) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------------
Limit
Output: t1.c1
-> Merge Semi Join
@ -1350,12 +1350,12 @@ SELECT t1.c1 FROM ft1 t1 WHERE EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c1)
Merge Cond: (t1.c1 = t2.c1)
-> Foreign Scan on public.ft1 t1
Output: t1.c1
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
-> Materialize
Output: t2.c1
-> Foreign Scan on public.ft2 t2
Output: t2.c1
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
(13 rows)
SELECT t1.c1 FROM ft1 t1 WHERE EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c1) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
@ -1376,8 +1376,8 @@ SELECT t1.c1 FROM ft1 t1 WHERE EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c1)
-- ANTI JOIN, not pushed down
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c2) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
Output: t1.c1
-> Merge Anti Join
@ -1385,12 +1385,12 @@ SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2
Merge Cond: (t1.c1 = t2.c2)
-> Foreign Scan on public.ft1 t1
Output: t1.c1
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC
Remote SQL: SELECT "C 1" FROM "S 1"."T 1" ORDER BY "C 1" ASC NULLS LAST
-> Materialize
Output: t2.c2
-> Foreign Scan on public.ft2 t2
Output: t2.c2
Remote SQL: SELECT c2 FROM "S 1"."T 1" ORDER BY c2 ASC
Remote SQL: SELECT c2 FROM "S 1"."T 1" ORDER BY c2 ASC NULLS LAST
(13 rows)
SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 = t2.c2) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
@ -1448,8 +1448,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET 1
-- different server, not pushed down. No result expected.
EXPLAIN (COSTS false, VERBOSE)
SELECT t1.c1, t2.c1 FROM ft5 t1 JOIN ft6 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 100 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
Output: t1.c1, t2.c1
-> Merge Join
@ -1457,12 +1457,12 @@ SELECT t1.c1, t2.c1 FROM ft5 t1 JOIN ft6 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t
Merge Cond: (t2.c1 = t1.c1)
-> Foreign Scan on public.ft6 t2
Output: t2.c1, t2.c2, t2.c3
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC NULLS LAST
-> Materialize
Output: t1.c1, t1.c2, t1.c3
-> Foreign Scan on public.ft5 t1
Output: t1.c1, t1.c2, t1.c3
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC NULLS LAST
(13 rows)
SELECT t1.c1, t2.c1 FROM ft5 t1 JOIN ft6 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 100 LIMIT 10;
@ -1746,8 +1746,8 @@ EXECUTE join_stmt;
-- different user mappings
CREATE USER MAPPING FOR view_owner SERVER loopback;
EXPLAIN (COSTS false, VERBOSE) EXECUTE join_stmt;
QUERY PLAN
----------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------
Limit
Output: t1.c1, ft5.c1
-> Merge Join
@ -1755,12 +1755,12 @@ EXPLAIN (COSTS false, VERBOSE) EXECUTE join_stmt;
Merge Cond: (t1.c1 = ft5.c1)
-> Foreign Scan on public.ft5 t1
Output: t1.c1, t1.c2, t1.c3
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC NULLS LAST
-> Materialize
Output: ft5.c1, ft5.c2, ft5.c3
-> Foreign Scan on public.ft5
Output: ft5.c1, ft5.c2, ft5.c3
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC
Remote SQL: SELECT c1 FROM "S 1"."T 4" ORDER BY c1 ASC NULLS LAST
(13 rows)
EXECUTE join_stmt;
@ -3813,6 +3813,86 @@ select c2, count(*) from "S 1"."T 1" where c2 < 500 group by 1 order by 1;
407 | 100
(13 rows)
-- Above DMLs add data with c6 as NULL in ft1, so test ORDER BY NULLS LAST and NULLs
-- FIRST behavior here.
-- ORDER BY DESC NULLS LAST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 DESC NULLS LAST, c1 OFFSET 795 LIMIT 10;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------
Limit
Output: c1, c2, c3, c4, c5, c6, c7, c8
-> Foreign Scan on public.ft1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY c6 DESC NULLS LAST, "C 1" ASC NULLS LAST
(5 rows)
SELECT * FROM ft1 ORDER BY c6 DESC NULLS LAST, c1 OFFSET 795 LIMIT 10;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
------+-----+--------------------+------------------------------+--------------------------+------+------------+-----
960 | 42 | 00960_trig_update | Mon Mar 02 00:00:00 1970 PST | Mon Mar 02 00:00:00 1970 | 0 | 0 | foo
970 | 42 | 00970_trig_update | Thu Mar 12 00:00:00 1970 PST | Thu Mar 12 00:00:00 1970 | 0 | 0 | foo
980 | 42 | 00980_trig_update | Sun Mar 22 00:00:00 1970 PST | Sun Mar 22 00:00:00 1970 | 0 | 0 | foo
990 | 42 | 00990_trig_update | Wed Apr 01 00:00:00 1970 PST | Wed Apr 01 00:00:00 1970 | 0 | 0 | foo
1000 | 42 | 01000_trig_update | Thu Jan 01 00:00:00 1970 PST | Thu Jan 01 00:00:00 1970 | 0 | 0 | foo
1218 | 818 | ggg_trig_update | | | (--; | ft2 |
1001 | 101 | 0000100001 | | | | ft2 |
1003 | 403 | 0000300003_update3 | | | | ft2 |
1004 | 104 | 0000400004 | | | | ft2 |
1006 | 106 | 0000600006 | | | | ft2 |
(10 rows)
-- ORDER BY DESC NULLS FIRST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 DESC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------
Limit
Output: c1, c2, c3, c4, c5, c6, c7, c8
-> Foreign Scan on public.ft1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY c6 DESC NULLS FIRST, "C 1" ASC NULLS LAST
(5 rows)
SELECT * FROM ft1 ORDER BY c6 DESC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
------+-----+-----------------+------------------------------+--------------------------+----+------------+-----
1020 | 100 | 0002000020 | | | | ft2 |
1101 | 201 | aaa | | | | ft2 |
1103 | 503 | ccc_update3 | | | | ft2 |
1104 | 204 | ddd | | | | ft2 |
1208 | 818 | fff_trig_update | | | | ft2 |
9 | 509 | 00009_update9 | Sat Jan 10 00:00:00 1970 PST | Sat Jan 10 00:00:00 1970 | 9 | ft2 | foo
19 | 509 | 00019_update9 | Tue Jan 20 00:00:00 1970 PST | Tue Jan 20 00:00:00 1970 | 9 | ft2 | foo
29 | 509 | 00029_update9 | Fri Jan 30 00:00:00 1970 PST | Fri Jan 30 00:00:00 1970 | 9 | ft2 | foo
39 | 509 | 00039_update9 | Mon Feb 09 00:00:00 1970 PST | Mon Feb 09 00:00:00 1970 | 9 | ft2 | foo
49 | 509 | 00049_update9 | Thu Feb 19 00:00:00 1970 PST | Thu Feb 19 00:00:00 1970 | 9 | ft2 | foo
(10 rows)
-- ORDER BY ASC NULLS FIRST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 ASC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------
Limit
Output: c1, c2, c3, c4, c5, c6, c7, c8
-> Foreign Scan on public.ft1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" ORDER BY c6 ASC NULLS FIRST, "C 1" ASC NULLS LAST
(5 rows)
SELECT * FROM ft1 ORDER BY c6 ASC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
------+-----+-------------------+------------------------------+--------------------------+------+------------+-----
1020 | 100 | 0002000020 | | | | ft2 |
1101 | 201 | aaa | | | | ft2 |
1103 | 503 | ccc_update3 | | | | ft2 |
1104 | 204 | ddd | | | | ft2 |
1208 | 818 | fff_trig_update | | | | ft2 |
1218 | 818 | ggg_trig_update | | | (--; | ft2 |
10 | 42 | 00010_trig_update | Sun Jan 11 00:00:00 1970 PST | Sun Jan 11 00:00:00 1970 | 0 | 0 | foo
20 | 42 | 00020_trig_update | Wed Jan 21 00:00:00 1970 PST | Wed Jan 21 00:00:00 1970 | 0 | 0 | foo
30 | 42 | 00030_trig_update | Sat Jan 31 00:00:00 1970 PST | Sat Jan 31 00:00:00 1970 | 0 | 0 | foo
40 | 42 | 00040_trig_update | Tue Feb 10 00:00:00 1970 PST | Tue Feb 10 00:00:00 1970 | 0 | 0 | foo
(10 rows)
-- ===================================================================
-- test check constraints
-- ===================================================================
@ -4630,8 +4710,8 @@ analyze loct1;
-- inner join; expressions in the clauses appear in the equivalence class list
explain (verbose, costs off)
select foo.f1, loct1.f1 from foo join loct1 on (foo.f1 = loct1.f1) order by foo.f2 offset 10 limit 10;
QUERY PLAN
---------------------------------------------------------------------------------------
QUERY PLAN
--------------------------------------------------------------------------------------------------
Limit
Output: foo.f1, loct1.f1, foo.f2
-> Sort
@ -4646,7 +4726,7 @@ explain (verbose, costs off)
Output: foo.f1, foo.f2
-> Foreign Scan on public.foo2
Output: foo2.f1, foo2.f2
Remote SQL: SELECT f1, f2 FROM public.loct1 ORDER BY f1 ASC
Remote SQL: SELECT f1, f2 FROM public.loct1 ORDER BY f1 ASC NULLS LAST
-> Index Only Scan using i_loct1_f1 on public.loct1
Output: loct1.f1
(17 rows)
@ -4670,8 +4750,8 @@ select foo.f1, loct1.f1 from foo join loct1 on (foo.f1 = loct1.f1) order by foo.
-- list but no output change as compared to the previous query
explain (verbose, costs off)
select foo.f1, loct1.f1 from foo left join loct1 on (foo.f1 = loct1.f1) order by foo.f2 offset 10 limit 10;
QUERY PLAN
---------------------------------------------------------------------------------------
QUERY PLAN
--------------------------------------------------------------------------------------------------
Limit
Output: foo.f1, loct1.f1, foo.f2
-> Sort
@ -4686,7 +4766,7 @@ explain (verbose, costs off)
Output: foo.f1, foo.f2
-> Foreign Scan on public.foo2
Output: foo2.f1, foo2.f2
Remote SQL: SELECT f1, f2 FROM public.loct1 ORDER BY f1 ASC
Remote SQL: SELECT f1, f2 FROM public.loct1 ORDER BY f1 ASC NULLS LAST
-> Index Only Scan using i_loct1_f1 on public.loct1
Output: loct1.f1
(17 rows)

12
contrib/postgres_fdw/sql/postgres_fdw.sql
Unescape View File

@ -677,6 +677,18 @@ commit;
select c2, count(*) from ft2 where c2 < 500 group by 1 order by 1;
select c2, count(*) from "S 1"."T 1" where c2 < 500 group by 1 order by 1;
-- Above DMLs add data with c6 as NULL in ft1, so test ORDER BY NULLS LAST and NULLs
-- FIRST behavior here.
-- ORDER BY DESC NULLS LAST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 DESC NULLS LAST, c1 OFFSET 795 LIMIT 10;
SELECT * FROM ft1 ORDER BY c6 DESC NULLS LAST, c1 OFFSET 795 LIMIT 10;
-- ORDER BY DESC NULLS FIRST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 DESC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
SELECT * FROM ft1 ORDER BY c6 DESC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
-- ORDER BY ASC NULLS FIRST options
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 ORDER BY c6 ASC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
SELECT * FROM ft1 ORDER BY c6 ASC NULLS FIRST, c1 OFFSET 15 LIMIT 10;
-- ===================================================================
-- test check constraints
-- ===================================================================

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