Re: transaction id wraparound

Hi sriram,

datfrozenxid column of pg_database row is updated at the completion of any
database wide vacuum operation. The value store here is the cuttoff xid used
by the vacuum operation all xid's older then this cutoffxid are replaced by
theis xid so i think the behaviour being shown by your database is quite
normal.

Regards
Talha Khan

The datfrozenxid column of a database's pg_database row is updated at the
completion of any database-wide VACUUM operation (i.e., VACUUM that does not
name a specific table). The value stored in this field is the freeze cutoff
XID that was used by that VACUUM command. All normal XIDs older than this
cutoff XID are guaranteed to have been replaced by FrozenXID within that
database

On 9/28/06, Sriram Dandapani <sdandapani(at)counterpane(dot)com> wrote:
>
> When I run this query
>
>
>
> fwdb01=# select current_timestamp,datname,age(datfrozenxid) from
> pg_database;
>
> now | datname | age
>
> -------------------------------+-----------+------------
>
> 2006-09-28 18:04:24.489935+00 | postgres | 1087834006
>
> 2006-09-28 18:04:24.489935+00 | fwdb01 | 2039254861
>
> 2006-09-28 18:04:24.489935+00 | template1 | 2039253122
>
> 2006-09-28 18:04:24.489935+00 | template0 | 1542808250
>
> (4 rows)
>
>
>
> fwdb01=# select current_timestamp,datname,age(datfrozenxid) from
> pg_database;
>
> now | datname | age
>
> ------------------------------+-----------+------------
>
> 2006-09-28 18:10:45.64452+00 | postgres | 1088357075
>
> 2006-09-28 18:10:45.64452+00 | fwdb01 | 2039777930
>
> 2006-09-28 18:10:45.64452+00 | template1 | 2039776191
>
> 2006-09-28 18:10:45.64452+00 | template0 | 1543331319
>
>
>
>
>
> In approximately 6 minutes, the fwdb01 count has gone up by about 500K. I
> am generating about 250K rows for every 6 . I am also running vacuumdb.
>
>
>
> Does vacuumdb generate a lot of transactions that affects this counter.
>