Re: Pre-alloc ListCell's optimization

* Stephen Frost (sfrost(at)snowman(dot)net) wrote:
> So, when it comes to palloc() reduction, this patch would eliminate 99%
> of palloc's due to lists. For the regression tests, we're talking about
> reducing 893,206 palloc calls to only 1.

Apologies, that wasn't quite right- it'd reduce it to 1 palloc call for
each of the 893,206 lists. In terms of actual comparison of palloc
calls, we have to look at how many are done today for those lists:

palloc calls for:

1-node lists: 1143794
2-node lists: 673071
3-node lists: 205364
4-node lists: 133650
5-node lists: 60552
6-node lists: 28896
7-node lists: 13248
8-node lists: 27045

Total: 2,285,620

Instead, we'd have 1 palloc call for each list, or 893,206, so we'd be
removing ~1.4M calls across the regression suite.

I'll work on cleaning up the patch to be committable early in the 9.3
dev cycle, so it can get a lot of testing prior to the next release.

Thanks,

Stephen