Speedup DFSchema::merge using HashSet indices

[simonvandel]

Which issue does this PR close?

Relates to #5637

Rationale for this change

Planning time of Datafusion is slow.

What changes are included in this PR?

Profiling shows that a large part of planning is spent in DFSchema::merge.
Before this PR, merging was complexity O(N * M), where N and M are number of fields in the two schemas.
With this PR, merging is complexity O(N + M) using a HashSet as an index.

Speeds up benchmarks in sql_planner.rs by 18-75%. However, physical planning benchmarks seem to regress by 1.8%. I wonder if that is an acceptable trade?

CC @matthewmturner who seems interested in planning performance

Benchmark results

Gnuplot not found, using plotters backend
Benchmarking logical_select_one_from_700: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 6.8s, enable flat sampling, or reduce sample count to 60.
logical_select_one_from_700
                        time:   [1.3324 ms 1.3359 ms 1.3396 ms]
                        change: [-54.725% -54.348% -53.914%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  6 (6.00%) low mild
  3 (3.00%) high mild
  5 (5.00%) high severe

physical_select_one_from_700
                        time:   [4.6236 ms 4.6485 ms 4.6795 ms]
                        change: [-75.159% -74.941% -74.735%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  3 (3.00%) high mild
  5 (5.00%) high severe

Benchmarking logical_trivial_join_low_numbered_columns: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 6.8s, enable flat sampling, or reduce sample count to 60.
logical_trivial_join_low_numbered_columns
                        time:   [1.3504 ms 1.3546 ms 1.3592 ms]
                        change: [-22.854% -22.042% -21.199%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
  1 (1.00%) low mild
  4 (4.00%) high mild
  6 (6.00%) high severe

Benchmarking logical_trivial_join_high_numbered_columns: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 7.1s, enable flat sampling, or reduce sample count to 50.
logical_trivial_join_high_numbered_columns
                        time:   [1.3961 ms 1.4003 ms 1.4051 ms]
                        change: [-21.654% -21.238% -20.848%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 12 outliers among 100 measurements (12.00%)
  2 (2.00%) low mild
  8 (8.00%) high mild
  2 (2.00%) high severe

Benchmarking logical_aggregate_with_join: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 9.3s, enable flat sampling, or reduce sample count to 50.
logical_aggregate_with_join
                        time:   [1.8286 ms 1.8331 ms 1.8381 ms]
                        change: [-18.973% -18.543% -18.126%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 8 outliers among 100 measurements (8.00%)
  1 (1.00%) low mild
  6 (6.00%) high mild
  1 (1.00%) high severe

physical_plan_tpch      time:   [5.6537 ms 5.6803 ms 5.7095 ms]
                        change: [+1.1125% +1.7618% +2.3821%] (p = 0.00 < 0.05)
                        Performance has regressed.
Found 9 outliers among 100 measurements (9.00%)
  6 (6.00%) high mild
  3 (3.00%) high severe

Are these changes tested?

Should be in existing tests.

Are there any user-facing changes?

Faster planning.

[matthewmturner]

Nice 😀

Trade off seems worth it.

I'm curious what's going on in that TPCH benchmark though as the other physical select benchmark showed solid improvement so not sure it's all physical planning.

[comphead]

lgtm thanks @simonvandel

[alamb]

Speeds up benchmarks in sql_planner.rs by 18-75%. However, physical planning benchmarks seem to regress by 1.8%. I wonder if that is an acceptable trade?

I think this is an acceptable trade

[alamb]

Thank you very much @simonvandel 🙏

[simonvandel]

Anything I need to do before we can merge this?

[alamb]

Thanks again @simonvandel and @matthewmturner and @comphead