Re: Sync Rep: First Thoughts on Code

On Wed, 2008-12-17 at 12:07 +0900, Fujii Masao wrote:

> OK. I will extend synchronous_replication, make walsender send XLOG
> with synchronization mode flag and make walreceiver perform according
> to the flag.

Sounds good.

> > My perspective is that synchronous_replication specifies how long to
> > wait. Current settings are "off" (don't wait) or "on" (meaning wait
> > until point #3). So I think we should change this to a list of options
> > to allow people to more carefully select how much waiting is required.
>
> In the latest patch, "off" keeps us waiting for replication in some
> cases, e.g. forceSyncCommit = true. This is analogous to the way
> synchronous_commit works. When "off" keeps us waiting for
> replication, which option (#1-#6) should we choose? Should it be
> user-configurable (though the parameter values are doubled)?
> hardcode #3? "off" always should not keep us waiting for
> replication?

I would hard code #4, i.e. make it fsync, so that DDL changes are
regarded as "high value transactions".

A parameter sounds like overkill. We'd need to explain what
forceSyncCommit does to users then, which is easier to avoid.

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Simon Riggs www.2ndQuadrant.com
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