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Redo postgres_fdw's planner code so it can handle parameterized paths.

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I wasn't going to ship this without having at least some example of how
to do that.  This version isn't terribly bright; in particular it won't
consider any combinations of multiple join clauses.  Given the cost of
executing a remote EXPLAIN, I'm not sure we want to be very aggressive
about doing that, anyway.

In support of this, refactor generate_implied_equalities_for_indexcol
so that it can be used to extract equivalence clauses that aren't
necessarily tied to an index.
This commit is contained in:
Tom Lane
2013-03-21 19:43:59 -04:00
parent 08af1a0a2a
commit 9cbc4b80dd
8 changed files with 943 additions and 577 deletions
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23
contrib/postgres_fdw/expected/postgres_fdw.out
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@ -446,6 +446,27 @@ EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c8 = 'foo'; -- can't
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
(4 rows)
-- parameterized remote path
EXPLAIN (VERBOSE, COSTS false)
SELECT * FROM ft2 a, ft2 b WHERE a.c1 = 47 AND b.c1 = a.c2;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------
Nested Loop
Output: a.c1, a.c2, a.c3, a.c4, a.c5, a.c6, a.c7, a.c8, b.c1, b.c2, b.c3, b.c4, b.c5, b.c6, b.c7, b.c8
-> Foreign Scan on public.ft2 a
Output: a.c1, a.c2, a.c3, a.c4, a.c5, a.c6, a.c7, a.c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" = 47))
-> Foreign Scan on public.ft2 b
Output: b.c1, b.c2, b.c3, b.c4, b.c5, b.c6, b.c7, b.c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (($1::integer = "C 1"))
(8 rows)
SELECT * FROM ft2 a, ft2 b WHERE a.c1 = 47 AND b.c1 = a.c2;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8 | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----+----+----+-------+------------------------------+--------------------------+----+------------+-----
47 | 7 | 00047 | Tue Feb 17 00:00:00 1970 PST | Tue Feb 17 00:00:00 1970 | 7 | 7 | foo | 7 | 7 | 00007 | Thu Jan 08 00:00:00 1970 PST | Thu Jan 08 00:00:00 1970 | 7 | 7 | foo
(1 row)
-- ===================================================================
-- parameterized queries
-- ===================================================================
@ -646,7 +667,7 @@ EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = $1)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" = $2::integer))
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" = $1::integer))
(4 rows)
EXECUTE st5('foo', 1);