Try to stabilize EXPLAIN output in partition_check test.

Commit 7d8ac981 adjusted these
tests in the hope of preserving the plan shape, but I failed to
notice that the three partitions were, on my local machine, choosing
two different plan shapes.  This is probably related to the fact
that all three tables have exactly the same row count.  Try to
improve the situation by making pht1_e about half as large as
the other two.

Per Tom Lane and the buildfarm.

Discussion: http://postgr.es/m/25380.1519277713@sss.pgh.pa.us

src/test/regress/expected/partition_join.out

@@ -1285,13 +1285,13 @@ CREATE TABLE pht1_e (a int, b int, c text) PARTITION BY HASH(ltrim(c, 'A'));
 CREATE TABLE pht1_e_p1 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 0);
 CREATE TABLE pht1_e_p2 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 1);
 CREATE TABLE pht1_e_p3 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 2);
-INSERT INTO pht1_e SELECT i, i, 'A' || to_char(i/50, 'FM0000') FROM generate_series(0, 599, 2) i;
+INSERT INTO pht1_e SELECT i, i, 'A' || to_char(i/50, 'FM0000') FROM generate_series(0, 299, 2) i;
 ANALYZE pht1_e;
 -- test partition matching with N-way join
 EXPLAIN (COSTS OFF)
 SELECT avg(t1.a), avg(t2.b), avg(t3.a + t3.b), t1.c, t2.c, t3.c FROM pht1 t1, pht2 t2, pht1_e t3 WHERE t1.b = t2.b AND t1.c = t2.c AND ltrim(t3.c, 'A') = t1.c GROUP BY t1.c, t2.c, t3.c ORDER BY t1.c, t2.c, t3.c;
-                                         QUERY PLAN                                         
---------------------------------------------------------------------------------------------
+                                      QUERY PLAN                                      
+--------------------------------------------------------------------------------------
  GroupAggregate
    Group Key: t1.c, t2.c, t3.c
    ->  Sort
@@ -1308,41 +1308,35 @@ SELECT avg(t1.a), avg(t2.b), avg(t3.a + t3.b), t1.c, t2.c, t3.c FROM pht1 t1, ph
                            ->  Hash
                                  ->  Seq Scan on pht1_e_p1 t3
                      ->  Hash Join
-                           Hash Cond: (ltrim(t3_1.c, 'A'::text) = t1_1.c)
-                           ->  Seq Scan on pht1_e_p2 t3_1
+                           Hash Cond: (t1_1.c = ltrim(t3_1.c, 'A'::text))
+                           ->  Hash Join
+                                 Hash Cond: ((t1_1.b = t2_1.b) AND (t1_1.c = t2_1.c))
+                                 ->  Seq Scan on pht1_p2 t1_1
+                                 ->  Hash
+                                       ->  Seq Scan on pht2_p2 t2_1
                            ->  Hash
-                                 ->  Hash Join
-                                       Hash Cond: ((t1_1.b = t2_1.b) AND (t1_1.c = t2_1.c))
-                                       ->  Seq Scan on pht1_p2 t1_1
-                                       ->  Hash
-                                             ->  Seq Scan on pht2_p2 t2_1
+                                 ->  Seq Scan on pht1_e_p2 t3_1
                      ->  Hash Join
-                           Hash Cond: (ltrim(t3_2.c, 'A'::text) = t1_2.c)
-                           ->  Seq Scan on pht1_e_p3 t3_2
+                           Hash Cond: (t1_2.c = ltrim(t3_2.c, 'A'::text))
+                           ->  Hash Join
+                                 Hash Cond: ((t1_2.b = t2_2.b) AND (t1_2.c = t2_2.c))
+                                 ->  Seq Scan on pht1_p3 t1_2
+                                 ->  Hash
+                                       ->  Seq Scan on pht2_p3 t2_2
                            ->  Hash
-                                 ->  Hash Join
-                                       Hash Cond: ((t1_2.b = t2_2.b) AND (t1_2.c = t2_2.c))
-                                       ->  Seq Scan on pht1_p3 t1_2
-                                       ->  Hash
-                                             ->  Seq Scan on pht2_p3 t2_2
+                                 ->  Seq Scan on pht1_e_p3 t3_2
 (33 rows)
 
 SELECT avg(t1.a), avg(t2.b), avg(t3.a + t3.b), t1.c, t2.c, t3.c FROM pht1 t1, pht2 t2, pht1_e t3 WHERE t1.b = t2.b AND t1.c = t2.c AND ltrim(t3.c, 'A') = t1.c GROUP BY t1.c, t2.c, t3.c ORDER BY t1.c, t2.c, t3.c;
-         avg          |         avg          |          avg          |  c   |  c   |   c   
-----------------------+----------------------+-----------------------+------+------+-------
-  24.0000000000000000 |  24.0000000000000000 |   48.0000000000000000 | 0000 | 0000 | A0000
-  75.0000000000000000 |  75.0000000000000000 |  148.0000000000000000 | 0001 | 0001 | A0001
- 123.0000000000000000 | 123.0000000000000000 |  248.0000000000000000 | 0002 | 0002 | A0002
- 174.0000000000000000 | 174.0000000000000000 |  348.0000000000000000 | 0003 | 0003 | A0003
- 225.0000000000000000 | 225.0000000000000000 |  448.0000000000000000 | 0004 | 0004 | A0004
- 273.0000000000000000 | 273.0000000000000000 |  548.0000000000000000 | 0005 | 0005 | A0005
- 324.0000000000000000 | 324.0000000000000000 |  648.0000000000000000 | 0006 | 0006 | A0006
- 375.0000000000000000 | 375.0000000000000000 |  748.0000000000000000 | 0007 | 0007 | A0007
- 423.0000000000000000 | 423.0000000000000000 |  848.0000000000000000 | 0008 | 0008 | A0008
- 474.0000000000000000 | 474.0000000000000000 |  948.0000000000000000 | 0009 | 0009 | A0009
- 525.0000000000000000 | 525.0000000000000000 | 1048.0000000000000000 | 0010 | 0010 | A0010
- 573.0000000000000000 | 573.0000000000000000 | 1148.0000000000000000 | 0011 | 0011 | A0011
-(12 rows)
+         avg          |         avg          |         avg          |  c   |  c   |   c   
+----------------------+----------------------+----------------------+------+------+-------
+  24.0000000000000000 |  24.0000000000000000 |  48.0000000000000000 | 0000 | 0000 | A0000
+  75.0000000000000000 |  75.0000000000000000 | 148.0000000000000000 | 0001 | 0001 | A0001
+ 123.0000000000000000 | 123.0000000000000000 | 248.0000000000000000 | 0002 | 0002 | A0002
+ 174.0000000000000000 | 174.0000000000000000 | 348.0000000000000000 | 0003 | 0003 | A0003
+ 225.0000000000000000 | 225.0000000000000000 | 448.0000000000000000 | 0004 | 0004 | A0004
+ 273.0000000000000000 | 273.0000000000000000 | 548.0000000000000000 | 0005 | 0005 | A0005
+(6 rows)
 
 --
 -- multiple levels of partitioning

src/test/regress/sql/partition_join.sql

@@ -253,7 +253,7 @@ CREATE TABLE pht1_e (a int, b int, c text) PARTITION BY HASH(ltrim(c, 'A'));
 CREATE TABLE pht1_e_p1 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 0);
 CREATE TABLE pht1_e_p2 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 1);
 CREATE TABLE pht1_e_p3 PARTITION OF pht1_e FOR VALUES WITH (MODULUS 3, REMAINDER 2);
-INSERT INTO pht1_e SELECT i, i, 'A' || to_char(i/50, 'FM0000') FROM generate_series(0, 599, 2) i;
+INSERT INTO pht1_e SELECT i, i, 'A' || to_char(i/50, 'FM0000') FROM generate_series(0, 299, 2) i;
 ANALYZE pht1_e;
 
 -- test partition matching with N-way join