Re: Problem with streaming replication, backups, and recovery (9.0.x)

On Tue, Mar 29, 2011 at 11:13:07AM +0900, Fujii Masao wrote:
> Yes, it's intentional. In streaming replication, at first the master must stream
> a backup history file to the standby in order to let it know the recovery ending
> position. But streaming replication doesn't have ability to send a text file, so
> we changed the code so that the recovery ending position was also written as
> WAL record which can be streamed.

ok, this makes sense.

> BTW, in my system, I use another trick to take a base backup from the
> standby:
> 
> (All of these operations are expected to be performed on the standby)
> (1) Run CHECKPOINT
> (2) Copy pg_control to temporary area
> (3) Take a base backup of $PGDATA
> (4) Copy back pg_control from temporary area to the backup taken in (2).
> (5) Calculate the recovery ending position from current pg_control in
>      $PGDATA by using pg_controldata
> 
> When recovery starts from that backup, it doesn't automatically check
> whether it has reached the ending position or not. So the user needs to
> check that manually.
> Yeah, this trick is very fragile and complicated. I'd like to improve the way
> in 9.2.

I know about it, but I feel very worried about doing stuff like this -
i.e. meddling with internal files of pg.

Best regards,

depesz

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