Combine cmin and cmax fields of HeapTupleHeaders into a single field, by

keeping private state in each backend that has inserted and deleted the same
tuple during its current top-level transaction.  This is sufficient since
there is no need to be able to determine the cmin/cmax from any other
transaction.  This gets us back down to 23-byte headers, removing a penalty
paid in 8.0 to support subtransactions.  Patch by Heikki Linnakangas, with
minor revisions by moi, following a design hashed out awhile back on the
pghackers list.

6 files changed, 347 insertions, 9 deletions

diff --git a/src/test/regress/expected/combocid.out b/src/test/regress/expected/combocid.out
new file mode 100644
index 00000000000..14e45fe4893
--- /dev/null
+++ b/src/test/regress/expected/combocid.out
@@ -0,0 +1,242 @@
+--
+-- Tests for some likely failure cases with combo cmin/cmax mechanism
+--
+CREATE TEMP TABLE combocidtest (foobar int);
+BEGIN;
+-- a few dummy ops to push up the CommandId counter
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+INSERT INTO combocidtest VALUES (1);
+INSERT INTO combocidtest VALUES (2);
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |   10 |      1
+ (0,2) |   11 |      2
+(2 rows)
+
+SAVEPOINT s1;
+UPDATE combocidtest SET foobar = foobar + 10;
+-- here we should see only updated tuples
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,3) |   13 |     11
+ (0,4) |   13 |     12
+(2 rows)
+
+ROLLBACK TO s1;
+-- now we should see old tuples, but with combo CIDs starting at 0
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    0 |      1
+ (0,2) |    1 |      2
+(2 rows)
+
+COMMIT;
+-- combo data is not there anymore, but should still see tuples
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    0 |      1
+ (0,2) |    1 |      2
+(2 rows)
+
+-- Test combo cids with portals
+BEGIN;
+INSERT INTO combocidtest VALUES (333);
+DECLARE c CURSOR FOR SELECT ctid,cmin,* FROM combocidtest;
+DELETE FROM combocidtest;
+FETCH ALL FROM c;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    2 |      1
+ (0,2) |    2 |      2
+ (0,5) |    0 |    333
+(3 rows)
+
+ROLLBACK;
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    2 |      1
+ (0,2) |    2 |      2
+(2 rows)
+
+-- check behavior with locked tuples
+BEGIN;
+-- a few dummy ops to push up the CommandId counter
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+SELECT 1;
+ ?column? 
+----------
+        1
+(1 row)
+
+INSERT INTO combocidtest VALUES (444);
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    2 |      1
+ (0,2) |    2 |      2
+ (0,6) |   10 |    444
+(3 rows)
+
+SAVEPOINT s1;
+-- this doesn't affect cmin
+SELECT ctid,cmin,* FROM combocidtest FOR UPDATE;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    2 |      1
+ (0,2) |    2 |      2
+ (0,6) |   10 |    444
+(3 rows)
+
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |    2 |      1
+ (0,2) |    2 |      2
+ (0,6) |   10 |    444
+(3 rows)
+
+-- but this does
+UPDATE combocidtest SET foobar = foobar + 10;
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,7) |   14 |     11
+ (0,8) |   14 |     12
+ (0,9) |   14 |    454
+(3 rows)
+
+ROLLBACK TO s1;
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |   14 |      1
+ (0,2) |   14 |      2
+ (0,6) |    0 |    444
+(3 rows)
+
+COMMIT;
+SELECT ctid,cmin,* FROM combocidtest;
+ ctid  | cmin | foobar 
+-------+------+--------
+ (0,1) |   14 |      1
+ (0,2) |   14 |      2
+ (0,6) |    0 |    444
+(3 rows)
+
diff --git a/src/test/regress/expected/without_oid.out b/src/test/regress/expected/without_oid.out
index c32daf815d6..cb2c0c01371 100644
--- a/src/test/regress/expected/without_oid.out
+++ b/src/test/regress/expected/without_oid.out
@@ -5,14 +5,15 @@
 -- This test tries to verify that WITHOUT OIDS actually saves space.
 -- On machines where MAXALIGN is 8, WITHOUT OIDS may or may not save any
 -- space, depending on the size of the tuple header + null bitmap.
--- As of 8.0 we need a 9-bit null bitmap to force the difference to appear.
+-- As of 8.3 we need a null bitmap of 8 or less bits for the difference
+-- to appear.
 --
 CREATE TABLE wi (i INT,
                  n1 int, n2 int, n3 int, n4 int,
-                 n5 int, n6 int, n7 int, n8 int) WITH OIDS;
+                 n5 int, n6 int, n7 int) WITH OIDS;
 CREATE TABLE wo (i INT,
                  n1 int, n2 int, n3 int, n4 int,
-                 n5 int, n6 int, n7 int, n8 int) WITHOUT OIDS;
+                 n5 int, n6 int, n7 int) WITHOUT OIDS;
 INSERT INTO wi VALUES (1);  -- 1
 INSERT INTO wo SELECT i FROM wi;  -- 1
 INSERT INTO wo SELECT i+1 FROM wi;  -- 1+1=2
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index efc1f1fef6e..096d2c1c7a7 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -1,6 +1,6 @@
 # ----------
 # The first group of parallel test
-# $PostgreSQL: pgsql/src/test/regress/parallel_schedule,v 1.38 2007/01/28 16:16:54 neilc Exp $
+# $PostgreSQL: pgsql/src/test/regress/parallel_schedule,v 1.39 2007/02/09 03:35:35 tgl Exp $
 # ----------
 test: boolean char name varchar text int2 int4 int8 oid float4 float8 bit numeric uuid
 
@@ -69,7 +69,7 @@ test: misc
 # ----------
 # The fifth group of parallel test
 # ----------
-test: select_views portals_p2 rules foreign_key cluster dependency guc
+test: select_views portals_p2 rules foreign_key cluster dependency guc combocid
 
 # ----------
 # The sixth group of parallel test
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 75e8b83138b..d109dabdc25 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -1,4 +1,4 @@
-# $PostgreSQL: pgsql/src/test/regress/serial_schedule,v 1.36 2007/01/28 16:16:54 neilc Exp $
+# $PostgreSQL: pgsql/src/test/regress/serial_schedule,v 1.37 2007/02/09 03:35:35 tgl Exp $
 # This should probably be in an order similar to parallel_schedule.
 test: boolean
 test: char
@@ -88,6 +88,7 @@ test: foreign_key
 test: cluster
 test: dependency
 test: guc
+test: combocid
 test: limit
 test: plpgsql
 test: copy2
diff --git a/src/test/regress/sql/combocid.sql b/src/test/regress/sql/combocid.sql
new file mode 100644
index 00000000000..3f30839b1f6
--- /dev/null
+++ b/src/test/regress/sql/combocid.sql
@@ -0,0 +1,93 @@
+--
+-- Tests for some likely failure cases with combo cmin/cmax mechanism
+--
+CREATE TEMP TABLE combocidtest (foobar int);
+
+BEGIN;
+
+-- a few dummy ops to push up the CommandId counter
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+
+INSERT INTO combocidtest VALUES (1);
+INSERT INTO combocidtest VALUES (2);
+
+SELECT ctid,cmin,* FROM combocidtest;
+
+SAVEPOINT s1;
+
+UPDATE combocidtest SET foobar = foobar + 10;
+
+-- here we should see only updated tuples
+SELECT ctid,cmin,* FROM combocidtest;
+
+ROLLBACK TO s1;
+
+-- now we should see old tuples, but with combo CIDs starting at 0
+SELECT ctid,cmin,* FROM combocidtest;
+
+COMMIT;
+
+-- combo data is not there anymore, but should still see tuples
+SELECT ctid,cmin,* FROM combocidtest;
+
+-- Test combo cids with portals
+BEGIN;
+
+INSERT INTO combocidtest VALUES (333);
+
+DECLARE c CURSOR FOR SELECT ctid,cmin,* FROM combocidtest;
+
+DELETE FROM combocidtest;
+
+FETCH ALL FROM c;
+
+ROLLBACK;
+
+SELECT ctid,cmin,* FROM combocidtest;
+
+-- check behavior with locked tuples
+BEGIN;
+
+-- a few dummy ops to push up the CommandId counter
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+SELECT 1;
+
+INSERT INTO combocidtest VALUES (444);
+
+SELECT ctid,cmin,* FROM combocidtest;
+
+SAVEPOINT s1;
+
+-- this doesn't affect cmin
+SELECT ctid,cmin,* FROM combocidtest FOR UPDATE;
+SELECT ctid,cmin,* FROM combocidtest;
+
+-- but this does
+UPDATE combocidtest SET foobar = foobar + 10;
+
+SELECT ctid,cmin,* FROM combocidtest;
+
+ROLLBACK TO s1;
+
+SELECT ctid,cmin,* FROM combocidtest;
+
+COMMIT;
+
+SELECT ctid,cmin,* FROM combocidtest;
diff --git a/src/test/regress/sql/without_oid.sql b/src/test/regress/sql/without_oid.sql
index 1a10a8533df..9fbb454d4dc 100644
--- a/src/test/regress/sql/without_oid.sql
+++ b/src/test/regress/sql/without_oid.sql
@@ -6,14 +6,15 @@
 -- This test tries to verify that WITHOUT OIDS actually saves space.
 -- On machines where MAXALIGN is 8, WITHOUT OIDS may or may not save any
 -- space, depending on the size of the tuple header + null bitmap.
--- As of 8.0 we need a 9-bit null bitmap to force the difference to appear.
+-- As of 8.3 we need a null bitmap of 8 or less bits for the difference
+-- to appear.
 --
 CREATE TABLE wi (i INT,
                  n1 int, n2 int, n3 int, n4 int,
-                 n5 int, n6 int, n7 int, n8 int) WITH OIDS;
+                 n5 int, n6 int, n7 int) WITH OIDS;
 CREATE TABLE wo (i INT,
                  n1 int, n2 int, n3 int, n4 int,
-                 n5 int, n6 int, n7 int, n8 int) WITHOUT OIDS;
+                 n5 int, n6 int, n7 int) WITHOUT OIDS;
 
 INSERT INTO wi VALUES (1);  -- 1
 INSERT INTO wo SELECT i FROM wi;  -- 1