Implement ALTER TABLE ... SPLIT PARTITION ... command

This new DDL command splits a single partition into several parititions.
Just like ALTER TABLE ... MERGE PARTITIONS ... command, new patitions are
created using createPartitionTable() function with parent partition as the
template.

This commit comprises quite naive implementation which works in single process
and holds the ACCESS EXCLUSIVE LOCK on the parent table during all the
operations including the tuple routing.  This is why this new DDL command
can't be recommended for large partitioned tables under a high load.  However,
this implementation come in handy in certain cases even as is.
Also, it could be used as a foundation for future implementations with lesser
locking and possibly parallel.

Discussion: https://postgr.es/m/c73a1746-0cd0-6bdd-6b23-3ae0b7c0c582%40postgrespro.ru
Author: Dmitry Koval
Reviewed-by: Matthias van de Meent, Laurenz Albe, Zhihong Yu, Justin Pryzby
Reviewed-by: Alvaro Herrera, Robert Haas, Stephane Tachoires

3 files changed, 245 insertions, 0 deletions

diff --git a/src/test/isolation/expected/partition-split.out b/src/test/isolation/expected/partition-split.out
new file mode 100644
index 00000000000..5d9e8b0925f
--- /dev/null
+++ b/src/test/isolation/expected/partition-split.out
@@ -0,0 +1,190 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1b s1splt s2b s2i s1c s2c s2s
+step s1b: BEGIN;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2b: BEGIN;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1b s1splt s2brr s2i s1c s2c s2s
+step s1b: BEGIN;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1b s1splt s2bs s2i s1c s2c s2s
+step s1b: BEGIN;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1brr s1splt s2b s2i s1c s2c s2s
+step s1brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2b: BEGIN;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1brr s1splt s2brr s2i s1c s2c s2s
+step s1brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1brr s1splt s2bs s2i s1c s2c s2s
+step s1brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1bs s1splt s2b s2i s1c s2c s2s
+step s1bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2b: BEGIN;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1bs s1splt s2brr s2i s1c s2c s2s
+step s1bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2brr: BEGIN ISOLATION LEVEL REPEATABLE READ;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
+
+starting permutation: s1bs s1splt s2bs s2i s1c s2c s2s
+step s1bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s1splt: ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20));
+step s2bs: BEGIN ISOLATION LEVEL SERIALIZABLE;
+step s2i: INSERT INTO tpart VALUES (1, 'text01'); <waiting ...>
+step s1c: COMMIT;
+step s2i: <... completed>
+step s2c: COMMIT;
+step s2s: SELECT * FROM tpart;
+ i|t     
+--+------
+ 5|text05
+ 1|text01
+15|text15
+25|text25
+35|text35
+(5 rows)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index 8bcaa8a6254..0342eb39e40 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -104,6 +104,7 @@ test: partition-key-update-2
 test: partition-key-update-3
 test: partition-key-update-4
 test: partition-merge
+test: partition-split
 test: plpgsql-toast
 test: cluster-conflict
 test: cluster-conflict-partition
diff --git a/src/test/isolation/specs/partition-split.spec b/src/test/isolation/specs/partition-split.spec
new file mode 100644
index 00000000000..087239a4a19
--- /dev/null
+++ b/src/test/isolation/specs/partition-split.spec
@@ -0,0 +1,54 @@
+# Verify that SPLIT operation locks DML operations with partitioned table
+
+setup
+{
+  DROP TABLE IF EXISTS tpart;
+  CREATE TABLE tpart(i int, t text) partition by range(i);
+  CREATE TABLE tpart_00_10 PARTITION OF tpart FOR VALUES FROM (0) TO (10);
+  CREATE TABLE tpart_10_20 PARTITION OF tpart FOR VALUES FROM (10) TO (20);
+  CREATE TABLE tpart_20_30 PARTITION OF tpart FOR VALUES FROM (20) TO (30);
+  CREATE TABLE tpart_default PARTITION OF tpart DEFAULT;
+  INSERT INTO tpart VALUES (5, 'text05');
+  INSERT INTO tpart VALUES (15, 'text15');
+  INSERT INTO tpart VALUES (25, 'text25');
+  INSERT INTO tpart VALUES (35, 'text35');
+}
+
+teardown
+{
+  DROP TABLE tpart;
+}
+
+session s1
+step s1b	{ BEGIN; }
+step s1brr	{ BEGIN ISOLATION LEVEL REPEATABLE READ; }
+step s1bs	{ BEGIN ISOLATION LEVEL SERIALIZABLE; }
+step s1splt	{ ALTER TABLE tpart SPLIT PARTITION tpart_10_20 INTO
+			   (PARTITION tpart_10_15 FOR VALUES FROM (10) TO (15),
+			    PARTITION tpart_15_20 FOR VALUES FROM (15) TO (20)); }
+step s1c	{ COMMIT; }
+
+
+session s2
+step s2b	{ BEGIN; }
+step s2brr	{ BEGIN ISOLATION LEVEL REPEATABLE READ; }
+step s2bs	{ BEGIN ISOLATION LEVEL SERIALIZABLE; }
+step s2i	{ INSERT INTO tpart VALUES (1, 'text01'); }
+step s2c	{ COMMIT; }
+step s2s	{ SELECT * FROM tpart; }
+
+
+# s1 starts SPLIT PARTITION then s2 trying to insert row and
+# waits until s1 finished SPLIT operation.
+
+permutation s1b s1splt s2b s2i s1c s2c s2s
+permutation s1b s1splt s2brr s2i s1c s2c s2s
+permutation s1b s1splt s2bs s2i s1c s2c s2s
+
+permutation s1brr s1splt s2b s2i s1c s2c s2s
+permutation s1brr s1splt s2brr s2i s1c s2c s2s
+permutation s1brr s1splt s2bs s2i s1c s2c s2s
+
+permutation s1bs s1splt s2b s2i s1c s2c s2s
+permutation s1bs s1splt s2brr s2i s1c s2c s2s
+permutation s1bs s1splt s2bs s2i s1c s2c s2s