Re: [HACKERS] make async slave to wait for lsn to be replayed

Hello,

I've changed the BEGIN WAIT FOR LSN statement to core functions 
pg_waitlsn, pg_waitlsn_infinite and pg_waitlsn_no_wait.
Currently the functions work inside repeatable read transactions, but 
waitlsn creates a snapshot if called first in a transaction block, which 
can possibly lead the transaction to working incorrectly, so the 
function gives a warning.

Usage examples
==========
select pg_waitlsn(‘LSN’, timeout);
select pg_waitlsn_infinite(‘LSN’);
select pg_waitlsn_no_wait(‘LSN’);