Re: Some questions about mammoth replication

On Thu, 11 Oct 2007 21:58:45 +0300
Hannu Krosing <hannu(at)skype(dot)net> wrote:

> > We have hooks in executor calling our own collecting functions, so
> > we don't need the trigger machinery to launch replication.
>
> But where do you store the collected info - in your own
> replication_log table,

No, we have our own transaction log outside the database.

> or do reuse data in WAL you extract it on
> master befor replication to slave (or on slave after moving the WAL) ?
>

We currently make zero use of WAL except to verify that the replication
data can be written.

> > > Do you make use of snapshot data, to make sure, what parts of WAL
> > > log are worth migrating to slaves , or do you just apply
> > > everything in WAL in separate transactions and abort if you find
> > > out that original transaction aborted ?
> >
> > We check if a data transaction is recorded in WAL before sending
> > it to a slave. For an aborted transaction we just discard all data
> > collected from that transaction.
>
> Do you duplicate postgresql's MVCC code for that, or will this happen
> automatically via using MVCC itself for collected data ?
>

Gonna have to wait for Alexey for the rest.

Joshua D. Drake

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