Tom Lane wrote:
> Attached is a patch against current CVS that fixes both of the known
> problems with sequences: failure to flush XLOG after a transaction
> that only does "SELECT nextval()", and failure to force a new WAL
> record to be written on the first nextval after a checkpoint.
> (The latter uses Vadim's idea of looking at the sequence page LSN.)
> I haven't tested it really extensively, but it seems to cure the
> reported problems.
I can confirm that the patch fixes the problem shown in my simple test:
test=> create table test (x serial, y varchar(255));
NOTICE: CREATE TABLE will create implicit sequence 'test_x_seq' for SERIAL column 'test.x'
NOTICE: CREATE TABLE / UNIQUE will create implicit index 'test_x_key' for table 'test'
CREATE
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16561 1
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16562 1
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16563 1
...
test=> select nextval('test_x_seq');nextval
--------- 22
(1 row)
test=> checkpoint;
CHECKPOINT
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16582 1
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16583 1
test=> insert into test (y) values ('lkjasdflkja sdfl;kj asdfl;kjasdf');
INSERT 16584 1
[ kill -9 to backend ]
#$ sql test
Welcome to psql, the PostgreSQL interactive terminal.
Type: \copyright for distribution terms \h for help with SQL commands \? for help on internal slash commands
\g or terminate with semicolon to execute query \q to quit
test=> select nextval('test_x_seq');nextval
--------- 56
(1 row)
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
