Home > mailing lists

Thread: How to detect txid visibility on standby server?

From

Sergey Burladyan

Date:

30 July 2014, 19:45:40

Hello!

Is it possible to detect what master transaction is visible on standby?

I try to use txid_current_snapshot() but it return wrong result on standby:

_master_:

create table tmp.txid_test(txid bigint, ss txid_snapshot)

begin;

insert into tmp.txid_test values (txid_current(), txid_current_snapshot());

select * from tmp.txid_test;

=> 9098493097 '9098489391:9098493097:9098489391,9098493002,9098493088'

_standby_:

select txid_visible_in_snapshot(9098493097, txid_current_snapshot());

=> t

select count(*) from tmp.txid_test;

=> 0

So, txid_visible_in_snapshot say what 9098493097 is visible, but realy it is not, it still not

commited on master and count on standby return 0 rows.

PS: And what does it exactly mean to get txid_current_snapshot() from standby?

Sergey Burladyan