postgres_fdw: Third attempt to stabilize regression tests.

Commit 1bc0100d27 added this test,
and commit 882ea509fe tried to
stabilize it.  There were still failures, so commit
958e20e42d tried again to stabilize
it.  That approach is still failing on jaguarundi, though, so
back it out and try something else.  Specifically, instead of
disabling remote estimates for the table in question, let's tell
autovacuum to leave it alone.

Etsuro Fujita

Discussion: http://postgr.es/m/5A82DCCE.3060107@lab.ntt.co.jp

contrib/postgres_fdw/expected/postgres_fdw.out

@@ -35,6 +35,9 @@ CREATE TABLE "S 1"."T 1" (
 	c8 user_enum,
 	CONSTRAINT t1_pkey PRIMARY KEY ("C 1")
 );
+-- "S 1"."T 1" will be heavily updated below, so disable autovacuum for
+-- the table to avoid unexpected effects of that
+ALTER TABLE "S 1"."T 1" SET (autovacuum_enabled = 'false');
 CREATE TABLE "S 1"."T 2" (
 	c1 int NOT NULL,
 	c2 text,
@@ -4244,10 +4247,6 @@ explain (verbose, costs off) select * from ft3 f, loct3 l
 -- ===================================================================
 -- test writable foreign table stuff
 -- ===================================================================
--- Autovacuum on the remote side might affect remote estimates,
--- so use local stats on ft2 as well
-ALTER FOREIGN TABLE ft2 OPTIONS (SET use_remote_estimate 'false');
-ANALYZE ft2;
 EXPLAIN (verbose, costs off)
 INSERT INTO ft2 (c1,c2,c3) SELECT c1+1000,c2+100, c3 || c3 FROM ft2 LIMIT 20;
                                                                                                                     QUERY PLAN                                                                                                                    
@@ -5524,32 +5523,32 @@ UPDATE ft2 SET c3 = 'baz'
   FROM ft4 INNER JOIN ft5 ON (ft4.c1 = ft5.c1)
   WHERE ft2.c1 > 2000 AND ft2.c2 === ft4.c1
   RETURNING ft2.*, ft4.*, ft5.*;                                                    -- can't be pushed down
-                                                                                                                                    QUERY PLAN                                                                                                                                     
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                          QUERY PLAN                                                                                                                                          
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Update on public.ft2
    Output: ft2.c1, ft2.c2, ft2.c3, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3
    Remote SQL: UPDATE "S 1"."T 1" SET c3 = $2 WHERE ctid = $1 RETURNING "C 1", c2, c3, c4, c5, c6, c7, c8
-   ->  Hash Join
+   ->  Nested Loop
          Output: ft2.c1, ft2.c2, NULL::integer, 'baz'::text, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft2.ctid, ft4.*, ft5.*, ft4.c1, ft4.c2, ft4.c3, ft5.c1, ft5.c2, ft5.c3
-         Hash Cond: (ft4.c1 = ft5.c1)
+         Join Filter: (ft2.c2 === ft4.c1)
+         ->  Foreign Scan on public.ft2
+               Output: ft2.c1, ft2.c2, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft2.ctid
+               Remote SQL: SELECT "C 1", c2, c4, c5, c6, c7, c8, ctid FROM "S 1"."T 1" WHERE (("C 1" > 2000)) FOR UPDATE
          ->  Foreign Scan
-               Output: ft2.c1, ft2.c2, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft2.ctid, ft4.*, ft4.c1, ft4.c2, ft4.c3
-               Filter: (ft2.c2 === ft4.c1)
-               Relations: (public.ft2) INNER JOIN (public.ft4)
-               Remote SQL: SELECT r1."C 1", r1.c2, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8, r1.ctid, CASE WHEN (r2.*)::text IS NOT NULL THEN ROW(r2.c1, r2.c2, r2.c3) END, r2.c1, r2.c2, r2.c3 FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 3" r2 ON (((r1."C 1" > 2000)))) FOR UPDATE OF r1
-               ->  Nested Loop
-                     Output: ft2.c1, ft2.c2, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft2.ctid, ft4.*, ft4.c1, ft4.c2, ft4.c3
-                     ->  Foreign Scan on public.ft2
-                           Output: ft2.c1, ft2.c2, ft2.c4, ft2.c5, ft2.c6, ft2.c7, ft2.c8, ft2.ctid
-                           Remote SQL: SELECT "C 1", c2, c4, c5, c6, c7, c8, ctid FROM "S 1"."T 1" WHERE (("C 1" > 2000)) FOR UPDATE
+               Output: ft4.*, ft4.c1, ft4.c2, ft4.c3, ft5.*, ft5.c1, ft5.c2, ft5.c3
+               Relations: (public.ft4) INNER JOIN (public.ft5)
+               Remote SQL: SELECT CASE WHEN (r2.*)::text IS NOT NULL THEN ROW(r2.c1, r2.c2, r2.c3) END, r2.c1, r2.c2, r2.c3, CASE WHEN (r3.*)::text IS NOT NULL THEN ROW(r3.c1, r3.c2, r3.c3) END, r3.c1, r3.c2, r3.c3 FROM ("S 1"."T 3" r2 INNER JOIN "S 1"."T 4" r3 ON (((r2.c1 = r3.c1))))
+               ->  Hash Join
+                     Output: ft4.*, ft4.c1, ft4.c2, ft4.c3, ft5.*, ft5.c1, ft5.c2, ft5.c3
+                     Hash Cond: (ft4.c1 = ft5.c1)
                      ->  Foreign Scan on public.ft4
                            Output: ft4.*, ft4.c1, ft4.c2, ft4.c3
                            Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 3"
-         ->  Hash
-               Output: ft5.*, ft5.c1, ft5.c2, ft5.c3
-               ->  Foreign Scan on public.ft5
-                     Output: ft5.*, ft5.c1, ft5.c2, ft5.c3
-                     Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 4"
+                     ->  Hash
+                           Output: ft5.*, ft5.c1, ft5.c2, ft5.c3
+                           ->  Foreign Scan on public.ft5
+                                 Output: ft5.*, ft5.c1, ft5.c2, ft5.c3
+                                 Remote SQL: SELECT c1, c2, c3 FROM "S 1"."T 4"
 (24 rows)
 
 UPDATE ft2 SET c3 = 'baz'
@@ -6003,9 +6002,7 @@ select c2, count(*) from "S 1"."T 1" where c2 < 500 group by 1 order by 1;
  407 |   100
 (13 rows)
 
--- Go back to use remote-estimate mode on ft2
 VACUUM ANALYZE "S 1"."T 1";
-ALTER FOREIGN TABLE ft2 OPTIONS (SET use_remote_estimate 'true');
 -- 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