Re: Macro customizable hashtable / bitmapscan & aggregation perf

Hi,

On 2016-10-11 02:38:26 +0200, Tomas Vondra wrote:
> Yes, I've done a bunch of TPC-H and TPC-DS tests on the patch, but it took
> quite a bit of time. These tests were done on a fairly small machine (the
> usual i5-2500k with 8GB of RAM), with only 1GB data sets for both
> benchmarks, to keep it completely in memory as I presume once we start
> hitting I/O, it becomes the dominant part.

Thanks!


> TPC-DS (tpcds.ods)
> ------------------
> 
> In this case, I'd say the results are less convincing. There are quite a few
> queries that got slower by ~10%, which is well above - for example queries
> 22 and 67. There are of course queries that got ~10% faster, and in total
> the patched version executed more queries (so overall the result is slightly
> positive, but not significantly).

That's interesting. I wonder whether that's plan changes just due to the
changing memory estimates, or what's causing that. I'll look into it.

Greetings,

Andres Freund