Re: Relation extension scalability

On Mon, Mar 30, 2015 at 8:57 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>
>
> If we're able to extend based on page-level locks rather than the global
> relation locking that we're doing now, then I'm not sure we really need
> to adjust how big the extents are any more. The reason for making
> bigger extents is because of the locking problem we have now when lots
> of backends want to extend a relation, but, if I'm following correctly,
> that'd go away with Andres' approach.
>

The benefit of extending in bigger chunks in background is that backend
would need to perform such an operation at relatively lesser frequency
which in itself could be a win.

> We don't have full patches for either of these and so I don't mind
> saying that, basically, I'd prefer to see if we still have a big
> bottleneck here with lots of backends trying to extend the same relation
> before we work on adding this particular feature in as it might end up
> being unnecessary.

Agreed, I think it is better to first see the results of current
patch on which Andres is working and then if someone is interested
and can show any real benefit with the patch to extend relation
in bigger chunks, then that might be worth consideration.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com