Re: Use merge-based matching for MCVs in eqjoinsel

On 08.09.2025 12:45, Ilia Evdokimov wrote:
>
> I realized I mistakenly copied the wrong results for the hash-map
> version in my previous draft. Sorry about that. Here are the correct
> benchmark results:
>
> Merge
>
> default_statistics_target | Planner Speedup (×) | Planner Before (ms) |
> Planner After (ms)
> --------------------------------------------------------------------------------
> 100                       | 1.00                | 1892.627            |
> 1898.622
> 1000                      | 1.12                | 2286.922            |
> 2033.553
> 2500                      | 1.92                | 4647.167            |
> 2423.552
> 5000                      | 5.94                | 17964.779           |
> 3025.739
> 7500                      | 10.48               | 38622.443           |
> 3684.262
> 10000                     | 16.72               | 69538.085           |
> 4159.418
>
>
> Hash-Map
>
> default_statistics_target | Planner Speedup (×) | Planner Before (ms) |
> Planner After (ms)
> --------------------------------------------------------------------------------
> 100                       | 1.00                | 1892.627            |
> 1886.969
> 1000                      | 1.09                | 2286.922            |
> 2100.099
> 2500                      | 1.94                | 4647.167            |
> 2400.711
> 5000                      | 6.15                | 17964.779           |
> 2919.914
> 7500                      | 10.58               | 38622.443           |
> 3650.375
> 10000                     | 16.33               | 69538.085           |
> 4257.864
>

It still seems to me like something is fishy with the numbers or
something in the benchmark adds a lot over overhead so that small
differences in eqjoinsel_inner() don't show here.

The delta between "hash" and "merge" for default_statistics_target=10000
should be the biggest but it's actually slower.

--
David Geier