Add extensive tests for partition pruning.

Currently, partition pruning happens via constraint exclusion, but
there are pending places to replace that with a different and
hopefully faster mechanism.  To be sure that we don't change behavior
without realizing it, add extensive test coverage.

Note that not all of these behaviors are optimal; in some cases,
partitions are not pruned even though it would be safe to do so.
These tests therefore serve to memorialize the current state rather
than the ideal state.  Patches that improve things can update the test
results as appropriate.

Amit Langote, adjusted by me.  Review and testing of the larger patch
set of which this is a part by Ashutosh Bapat, David Rowley, Dilip
Kumar, Jesper Pedersen, Rajkumar Raghuwanshi, Beena Emerson, Amul Sul,
and Kyotaro Horiguchi.

Discussion: http://postgr.es/m/098b9c71-1915-1a2a-8d52-1a7a50ce79e8@lab.ntt.co.jp

src/test/regress/parallel_schedule

@@ -116,7 +116,7 @@ test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid c
 # ----------
 # Another group of parallel tests
 # ----------
-test: identity partition_join reloptions hash_part
+test: identity partition_join partition_prune reloptions hash_part
 
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger

src/test/regress/serial_schedule

@@ -180,6 +180,7 @@ test: with
 test: xml
 test: identity
 test: partition_join
+test: partition_prune
 test: reloptions
 test: hash_part
 test: event_trigger

src/test/regress/sql/partition_prune.sql

+--
+-- Test partitioning planner code
+--
+create table lp (a char) partition by list (a);
+create table lp_default partition of lp default;
+create table lp_ef partition of lp for values in ('e', 'f');
+create table lp_ad partition of lp for values in ('a', 'd');
+create table lp_bc partition of lp for values in ('b', 'c');
+create table lp_g partition of lp for values in ('g');
+create table lp_null partition of lp for values in (null);
+explain (costs off) select * from lp;
+explain (costs off) select * from lp where a > 'a' and a < 'd';
+explain (costs off) select * from lp where a > 'a' and a <= 'd';
+explain (costs off) select * from lp where a = 'a';
+explain (costs off) select * from lp where 'a' = a;	/* commuted */
+explain (costs off) select * from lp where a is not null;
+explain (costs off) select * from lp where a is null;
+explain (costs off) select * from lp where a = 'a' or a = 'c';
+explain (costs off) select * from lp where a is not null and (a = 'a' or a = 'c');
+explain (costs off) select * from lp where a <> 'g';
+explain (costs off) select * from lp where a <> 'a' and a <> 'd';
+explain (costs off) select * from lp where a not in ('a', 'd');
+
+-- collation matches the partitioning collation, pruning works
+create table coll_pruning (a text collate "C") partition by list (a);
+create table coll_pruning_a partition of coll_pruning for values in ('a');
+create table coll_pruning_b partition of coll_pruning for values in ('b');
+create table coll_pruning_def partition of coll_pruning default;
+explain (costs off) select * from coll_pruning where a collate "C" = 'a' collate "C";
+-- collation doesn't match the partitioning collation, no pruning occurs
+explain (costs off) select * from coll_pruning where a collate "POSIX" = 'a' collate "POSIX";
+
+create table rlp (a int, b varchar) partition by range (a);
+create table rlp_default partition of rlp default partition by list (a);
+create table rlp_default_default partition of rlp_default default;
+create table rlp_default_10 partition of rlp_default for values in (10);
+create table rlp_default_30 partition of rlp_default for values in (30);
+create table rlp_default_null partition of rlp_default for values in (null);
+create table rlp1 partition of rlp for values from (minvalue) to (1);
+create table rlp2 partition of rlp for values from (1) to (10);
+
+create table rlp3 (b varchar, a int) partition by list (b varchar_ops);
+create table rlp3_default partition of rlp3 default;
+create table rlp3abcd partition of rlp3 for values in ('ab', 'cd');
+create table rlp3efgh partition of rlp3 for values in ('ef', 'gh');
+create table rlp3nullxy partition of rlp3 for values in (null, 'xy');
+alter table rlp attach partition rlp3 for values from (15) to (20);
+
+create table rlp4 partition of rlp for values from (20) to (30) partition by range (a);
+create table rlp4_default partition of rlp4 default;
+create table rlp4_1 partition of rlp4 for values from (20) to (25);
+create table rlp4_2 partition of rlp4 for values from (25) to (29);
+
+create table rlp5 partition of rlp for values from (31) to (maxvalue) partition by range (a);
+create table rlp5_default partition of rlp5 default;
+create table rlp5_1 partition of rlp5 for values from (31) to (40);
+
+explain (costs off) select * from rlp where a < 1;
+explain (costs off) select * from rlp where 1 > a;	/* commuted */
+explain (costs off) select * from rlp where a <= 1;
+explain (costs off) select * from rlp where a = 1;
+explain (costs off) select * from rlp where a = 1::bigint;		/* same as above */
+explain (costs off) select * from rlp where a = 1::numeric;	/* no pruning */
+explain (costs off) select * from rlp where a <= 10;
+explain (costs off) select * from rlp where a > 10;
+explain (costs off) select * from rlp where a < 15;
+explain (costs off) select * from rlp where a <= 15;
+explain (costs off) select * from rlp where a > 15 and b = 'ab';
+explain (costs off) select * from rlp where a = 16;
+explain (costs off) select * from rlp where a = 16 and b in ('not', 'in', 'here');
+explain (costs off) select * from rlp where a = 16 and b < 'ab';
+explain (costs off) select * from rlp where a = 16 and b <= 'ab';
+explain (costs off) select * from rlp where a = 16 and b is null;
+explain (costs off) select * from rlp where a = 16 and b is not null;
+explain (costs off) select * from rlp where a is null;
+explain (costs off) select * from rlp where a is not null;
+explain (costs off) select * from rlp where a > 30;
+explain (costs off) select * from rlp where a = 30;	/* only default is scanned */
+explain (costs off) select * from rlp where a <= 31;
+explain (costs off) select * from rlp where a = 1 or a = 7;
+explain (costs off) select * from rlp where a = 1 or b = 'ab';
+
+explain (costs off) select * from rlp where a > 20 and a < 27;
+explain (costs off) select * from rlp where a = 29;
+explain (costs off) select * from rlp where a >= 29;
+
+-- redundant clauses are eliminated
+explain (costs off) select * from rlp where a > 1 and a = 10;	/* only default */
+explain (costs off) select * from rlp where a > 1 and a >=15;	/* rlp3 onwards, including default */
+explain (costs off) select * from rlp where a = 1 and a = 3;	/* empty */
+explain (costs off) select * from rlp where (a = 1 and a = 3) or (a > 1 and a = 15);
+
+-- multi-column keys
+create table mc3p (a int, b int, c int) partition by range (a, abs(b), c);
+create table mc3p_default partition of mc3p default;
+create table mc3p0 partition of mc3p for values from (minvalue, minvalue, minvalue) to (1, 1, 1);
+create table mc3p1 partition of mc3p for values from (1, 1, 1) to (10, 5, 10);
+create table mc3p2 partition of mc3p for values from (10, 5, 10) to (10, 10, 10);
+create table mc3p3 partition of mc3p for values from (10, 10, 10) to (10, 10, 20);
+create table mc3p4 partition of mc3p for values from (10, 10, 20) to (10, maxvalue, maxvalue);
+create table mc3p5 partition of mc3p for values from (11, 1, 1) to (20, 10, 10);
+create table mc3p6 partition of mc3p for values from (20, 10, 10) to (20, 20, 20);
+create table mc3p7 partition of mc3p for values from (20, 20, 20) to (maxvalue, maxvalue, maxvalue);
+
+explain (costs off) select * from mc3p where a = 1;
+explain (costs off) select * from mc3p where a = 1 and abs(b) < 1;
+explain (costs off) select * from mc3p where a = 1 and abs(b) = 1;
+explain (costs off) select * from mc3p where a = 1 and abs(b) = 1 and c < 8;
+explain (costs off) select * from mc3p where a = 10 and abs(b) between 5 and 35;
+explain (costs off) select * from mc3p where a > 10;
+explain (costs off) select * from mc3p where a >= 10;
+explain (costs off) select * from mc3p where a < 10;
+explain (costs off) select * from mc3p where a <= 10 and abs(b) < 10;
+explain (costs off) select * from mc3p where a = 11 and abs(b) = 0;
+explain (costs off) select * from mc3p where a = 20 and abs(b) = 10 and c = 100;
+explain (costs off) select * from mc3p where a > 20;
+explain (costs off) select * from mc3p where a >= 20;
+explain (costs off) select * from mc3p where (a = 1 and abs(b) = 1 and c = 1) or (a = 10 and abs(b) = 5 and c = 10) or (a > 11 and a < 20);
+explain (costs off) select * from mc3p where (a = 1 and abs(b) = 1 and c = 1) or (a = 10 and abs(b) = 5 and c = 10) or (a > 11 and a < 20) or a < 1;
+explain (costs off) select * from mc3p where (a = 1 and abs(b) = 1 and c = 1) or (a = 10 and abs(b) = 5 and c = 10) or (a > 11 and a < 20) or a < 1 or a = 1;
+explain (costs off) select * from mc3p where a = 1 or abs(b) = 1 or c = 1;
+explain (costs off) select * from mc3p where (a = 1 and abs(b) = 1) or (a = 10 and abs(b) = 10);
+explain (costs off) select * from mc3p where (a = 1 and abs(b) = 1) or (a = 10 and abs(b) = 9);
+
+-- a simpler multi-column keys case
+create table mc2p (a int, b int) partition by range (a, b);
+create table mc2p_default partition of mc2p default;
+create table mc2p0 partition of mc2p for values from (minvalue, minvalue) to (1, minvalue);
+create table mc2p1 partition of mc2p for values from (1, minvalue) to (1, 1);
+create table mc2p2 partition of mc2p for values from (1, 1) to (2, minvalue);
+create table mc2p3 partition of mc2p for values from (2, minvalue) to (2, 1);
+create table mc2p4 partition of mc2p for values from (2, 1) to (2, maxvalue);
+create table mc2p5 partition of mc2p for values from (2, maxvalue) to (maxvalue, maxvalue);
+
+explain (costs off) select * from mc2p where a < 2;
+explain (costs off) select * from mc2p where a = 2 and b < 1;
+explain (costs off) select * from mc2p where a > 1;
+explain (costs off) select * from mc2p where a = 1 and b > 1;
+
+-- boolean partitioning
+create table boolpart (a bool) partition by list (a);
+create table boolpart_default partition of boolpart default;
+create table boolpart_t partition of boolpart for values in ('true');
+create table boolpart_f partition of boolpart for values in ('false');
+
+explain (costs off) select * from boolpart where a in (true, false);
+explain (costs off) select * from boolpart where a = false;
+explain (costs off) select * from boolpart where not a = false;
+explain (costs off) select * from boolpart where a is true or a is not true;
+explain (costs off) select * from boolpart where a is not true;
+explain (costs off) select * from boolpart where a is not true and a is not false;
+explain (costs off) select * from boolpart where a is unknown;
+explain (costs off) select * from boolpart where a is not unknown;
+
+drop table lp, coll_pruning, rlp, mc3p, mc2p, boolpart;