Re: libpq changes for synchronous replication

On 17/09/10 12:22, Fujii Masao wrote:
> On Fri, Sep 17, 2010 at 5:09 PM, Heikki Linnakangas
> <heikki.linnakangas@enterprisedb.com>  wrote:
>> That said, there's a few small things that can be progressed regardless of
>> the details of synchronous replication. There's the changes to trigger
>> failover with a signal, and it seems that we'll need some libpq changes to
>> allow acknowledgments to be sent back to the master regardless of the rest
>> of the design. We can discuss those in separate threads in parallel.
>
> Agreed. The attached patch introduces new function which is used
> to send ACK back from walreceiver. The function sends a message
> to XLOG stream by calling PQputCopyData. Also I allowed PQputCopyData
> to be called even during COPY OUT.

Oh, that's simple.

It doesn't feel right to always accept PQputCopyData in COPY OUT mode, 
though. IMHO there should be a new COPY IN+OUT mode.

It should be pretty safe to add a CopyInOutResponse message to the 
protocol without a protocol version bump. Thoughts on that?

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com