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* Vacuum freeze help
@ 2016-08-30 12:09 Ben Kammer <b_a_kammer@yahoo.co.uk>
2016-08-30 12:30 ` Re: Vacuum freeze help Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 2+ messages in thread
From: Ben Kammer @ 2016-08-30 12:09 UTC (permalink / raw)
To: pgsql-admin
Hello,
I have a postgresql 9.5.4 cluster and was testing with vacuum freeze. I expected the value of xmin to be set to '2' when I vacuum a particular table with the VACUUM FREEZE command. But for some reason this doesn't happen. Here is my small test:
test=# create table t1 (col1 int, col2 int);CREATE TABLEtest=# insert into t1 values (1,2), (3,4);INSERT 0 2test=# select xmin, xmax, * from t1; xmin | xmax | col1 | col2 ------+------+------+------ 1845 | 0 | 1 | 2 1845 | 0 | 3 | 4(2 rows)
test=# vacuum freeze t1;VACUUMtest=# select xmin, xmax, * from t1; xmin | xmax | col1 | col2 ------+------+------+------ 1845 | 0 | 1 | 2 1845 | 0 | 3 | 4(2 rows) As you can see from the results of the last select statement the value of xmin is 1845 instead of 2 which I expected it to be. On my 9.0 cluster this works fine. Has this behavior of postgresql been changed since 9.0? Can anyone explain this?
Ben.
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Vacuum freeze help
2016-08-30 12:09 Vacuum freeze help Ben Kammer <b_a_kammer@yahoo.co.uk>
@ 2016-08-30 12:30 ` Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2016-08-30 12:30 UTC (permalink / raw)
To: Ben Kammer <b_a_kammer@yahoo.co.uk>; +Cc: pgsql-admin
Ben Kammer <b_a_kammer@yahoo.co.uk> writes:
> I have a postgresql 9.5.4 cluster and was testing with vacuum freeze. I
> expected the value of xmin to be set to '2' when I vacuum a particular
> table with the VACUUM FREEZE command.
That doesn't happen anymore; freezing just sets an info bit that indicates
that the xmin should be treated as old.
regards, tom lane
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2016-08-30 12:09 Vacuum freeze help Ben Kammer <b_a_kammer@yahoo.co.uk>
2016-08-30 12:30 ` Tom Lane <tgl@sss.pgh.pa.us>
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