Re: Fast insertion indexes: why no developments

On 2013-11-04 11:27:33 -0500, Robert Haas wrote:
> On Mon, Nov 4, 2013 at 11:24 AM, Claudio Freire <klaussfreire(at)gmail(dot)com> wrote:
> > Such a thing would help COPY, so maybe it's worth a look
>
> I have little doubt that a deferred insertion buffer of some kind
> could help performance on some workloads, though I suspect the buffer
> would have to be pretty big to make it worthwhile on a big COPY that
> generates mostly-random insertions.

Even for random data presorting the to-be-inserted data appropriately
could result in much better io patterns.

> I think the question is not so
> much whether it's worth doing but where anyone's going to find the
> time to do it.

Yea :(

I think doing this outside of s_b will make stuff rather hard for
physical replication and crash recovery since we either will need to
flush the whole buffer at checkpoints - which is hard since the
checkpointer doesn't work inside individual databases - or we need to
persist the in-memory buffer across restart which also sucks.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services