Thread: [Autovacuum] Issue to understand some logs
Hi everybody,
I have trouble understanding some logs of postgreSQL.
Here you can find a log from the auto-vacuum process :
2012-12-17 16:38:58 CET LOG: automatic vacuum of table "flows.public.agg_t344_outgoing_a41_src_net_and_dst_net_f5":
indexscans: 0
pages: 0 removed, 59820 remain
tuples: 0 removed, 5801752 remain
system usage: CPU 0.93s/0.95u sec elapsed 423.07 sec
I am right to conclude that there is 5801752 available tuples in the previous table ?
If true, I am very confused because our table can not exceed 2592000 tuples (We delete old ones).
To be sure I tried to run the following query to count availables tuples :
select count(*) from agg_t344_outgoing_a41_src_net_and_dst_net_f5;
count
---------
2584398
(1 row)
Can someone give me a clue ?
Best regards,
Baptiste.
---
Baptiste LHOSTE
blhoste@alaloop.com
ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart
Téléphone : +33 (0) 5 59 41 51 10
www.alaloop.com
On Mon, 2012-12-17 at 16:57 +0100, Baptiste LHOSTE wrote: > Hi everybody, > > I have trouble understanding some logs of postgreSQL. > > Here you can find a log from the auto-vacuum process : > > 2012-12-17 16:38:58 CET LOG: automatic vacuum of table "flows.public.agg_t344_outgoing_a41_src_net_and_dst_net_f5": indexscans: 0 > pages: 0 removed, 59820 remain > tuples: 0 removed, 5801752 remain > system usage: CPU 0.93s/0.95u sec elapsed 423.07 sec > > I am right to conclude that there is 5801752 available tuples in the previous table ? > > If true, I am very confused because our table can not exceed 2592000 tuples (We delete old ones). > > To be sure I tried to run the following query to count availables tuples : > > select count(*) from agg_t344_outgoing_a41_src_net_and_dst_net_f5; > count > --------- > 2584398 > (1 row) > > Can someone give me a clue ? > It could be dead rows, still visible for other transactions. -- Guillaume http://blog.guillaume.lelarge.info http://www.dalibo.com
> It could be dead rows, still visible for other transactions. Ok but in this case, why the automatic vacuum task of the autovacuum process does not delete theses dead rows ? Best regards, Baptiste --- Baptiste LHOSTE blhoste@alaloop.com ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart Téléphone : +33 (0) 5 59 41 51 10 www.alaloop.com
On Mon, 2012-12-17 at 17:10 +0100, Baptiste LHOSTE wrote: > > It could be dead rows, still visible for other transactions. > > Ok but in this case, why the automatic vacuum task of the autovacuum process does not delete theses dead rows ? > As I said, because they are still visible to other transactions. Try to see if you have long-lasting transactions. -- Guillaume http://blog.guillaume.lelarge.info http://www.dalibo.com
>As I said, because they are still visible to other transactions. Try to >see if you have long-lasting transactions. How can I do that ? I check running query in pg_stat_activity, but there is no query on that table. Best regards, Baptiste. --- Baptiste LHOSTE blhoste@alaloop.com ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart Téléphone : +33 (0) 5 59 41 51 10 www.alaloop.com
I run a select on the pg_stat_all_tables and it returns that there is 0 n_dead_tup. I am really confused. Best regards, Baptiste. --- Baptiste LHOSTE blhoste@alaloop.com ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart Téléphone : +33 (0) 5 59 41 51 10 www.alaloop.com
Baptiste LHOSTE <blhoste@alaloop.com> writes:
>> As I said, because they are still visible to other transactions. Try to
>> see if you have long-lasting transactions.
> How can I do that ? I check running query in pg_stat_activity, but there is no query on that table.
Does "select * from pg_prepared_xacts" find anything?
regards, tom lane
> Does "select * from pg_prepared_xacts" find anything? Yes indeed, so I rollback our old prepared transactions. I will check tomorrow, and I will let you know. Best regards, Baptiste. --- Baptiste LHOSTE blhoste@alaloop.com ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart Téléphone : +33 (0) 5 59 41 51 10 www.alaloop.com
Thanks both of you for your help. The autovacuum process did the work yesterday. Best regards, Baptiste --- Baptiste LHOSTE blhoste@alaloop.com ALALOOP S.A.S. - Technopole Izarbel - 64210 Bidart Téléphone : +33 (0) 5 59 41 51 10 www.alaloop.com