Re: logical changeset generation v3

Hi,

On 2012-11-19 09:50:30 +0100, Andres Freund wrote:
> On 2012-11-19 16:28:55 +0900, Michael Paquier wrote:
> > After launching some SQLs, the logical receiver is stuck just after sending
> > INIT_LOGICAL_REPLICATION, please see bt of process waiting:
>
> Its waiting till it sees initial an initial xl_running_xacts record. The
> easiest way to do that is manually issue a checkpoint. Sorry, should
> have included that in the description.
> Otherwise you can wait till the next routine checkpoint comes arround...
>
> I plan to cause more xl_running_xacts record to be logged in the
> future. I think the timing of those currently is non-optimal, you have
> the same problem as here in normal streaming replication as well :(

This is "fixed" now with the changes I pushed a second ago. Unless some
longrunning transactions are arround we now immediately jump to a ready
state.
This is achieved by
1. regularly logging xl_running_xacts (in background writer)
2. logging xl_runnign_xacts at the beginning of INIT_LOGICAL_REPLICATION

This also has the advantage that the xmin horizon can be increased much
more frequently.

Greetings,

Andres Freund

--Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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