Re: [External] Slot issues

[bhargav kamineni <bhargavpostgres@xxxxxxxxx>]

postgres=# select * from pg_replication_slots ;

            slot_name             | plugin | slot_type | datoid | database | active | active_pid | xmin | catalog_xmin |  restart_lsn

----------------------------------+--------+-----------+--------+----------+--------+------------+------+--------------+---------------

 replication_slot |        | physical  |        |          | t      |      23185 |      |              | 7642/B07AC830

(1 row)

On Mon, 15 Oct 2018 at 01:34, Vijaykumar Jain <vjain@xxxxxxxxxxxxx> wrote:

from your master, can you give us the output of 

select * from pg_replication_slots;

maybe some stray slot exists that you may not be aware of ?

Regards,

Vijay

On Mon, Oct 15, 2018 at 1:08 AM Vijaykumar Jain <vjain@xxxxxxxxxxxxx> wrote:

ok my bad.

i just set one of the 9.6.9 versions to have max_replication_slots =2 and still i had to slots active.

ostgres=# table pg_replication_slots;

        slot_name        | plugin | slot_type | datoid | database | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_flush_lsn

-------------------------+--------+-----------+--------+----------+--------+------------+------+--------------+-------------+---------------------

 a02 |        | physical  |        |          | t      |      13719 |      |              | 2/D30000D0  |

a03 |        | physical  |        |          | t      |      13720 |      |              | 2/D30000D0  |

(2 rows)

postgres=# show max_replication_slots;

 max_replication_slots

-----------------------

 2

(1 row)

yep it should work with 2.

Regards,

Vijay

On Mon, Oct 15, 2018 at 1:02 AM Vijaykumar Jain <vjain@xxxxxxxxxxxxx> wrote:

I guess max_replication_slots has to be greater than active replication slots.

maybe you need to increase max_replication_slots to 3 to have 2 active slots.

Regards,

Vijay

On Mon, Oct 15, 2018 at 12:54 AM bhargav kamineni <bhargavpostgres@xxxxxxxxx> wrote:

 for 9.x. Default was 0.  we have set max_replication_slot =2 , one is already being used , postgres should use  second slot for another server but dono why its throwing error 

On Mon, 15 Oct 2018 at 00:32, Vijaykumar Jain <vjain@xxxxxxxxxxxxx> wrote:

I guess max_replication_slots has to >  current total slots in use. (and not >= ) 

https://www.postgresql.org/docs/10/static/runtime-config-replication.html

https://github.com/postgres/postgres/blob/d6e98ebe375e115c29028f9bd090f0f7e07e2527/src/backend/replication/slot.c#L1506

from the doc, it says defaults are 10, any reason why you have set it to 2. You need to set it at a value higher than number of slots active. 

also, i guess changing this parameter would require a server restart.

Regards,

Vijay

On Mon, Oct 15, 2018 at 12:16 AM bhargav kamineni <bhargavpostgres@xxxxxxxxx> wrote:

Hi Team,

I am getting this ERROR while starting my second slave server 

 

PANIC:  too many replication slots active before shutdown

HINT:  Increase max_replication_slots and try again.

max_replication_slots on my master is 2 and one of them is already active for another slave,

do i need to increase this parameter for the need of working of another slave ? if so whats the reason ?

Thanks

Bhargav K