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.