Re: SSI patch version 14

On 09.02.2011 17:58, Kevin Grittner wrote:
> Dan Ports<drkp(at)csail(dot)mit(dot)edu> wrote:
>
>> I think for SerializableXidHash we should probably just initially
>> allocate it at its maximum size. Then it'll match the PredXact
>> list which is allocated in full upfront, and there's no risk of
>> being able to allocate a transaction but not register its xid. In
>> fact, I believe there would be no way for starting a new
>> serializable transaction to fail.
>
> To be more precise, it would prevent an out of shared memory error
> during an attempt to register an xid for an active serializable
> transaction. That seems like a good thing. Patch to remove the
> hint and initially allocate that HTAB at full size attached.

Committed.

Curiously, coypu has gone green again. It's now choosing 40 connections
and 8 MB of shared_buffers, while it used to choose 30 connections and
24 MB of shared_buffers before the SSI patch. Looks like fixing the size
estimation bugs helped that, but I'm not entirely sure how. Maybe it
just failed with higher max_connections settings because of the
misestimate. But why does it now choose a *higher* max_connections
setting than before?

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