andygrove opened a new issue, #809:
URL: https://github.com/apache/datafusion-comet/issues/809
### What is the problem the feature request solves?
Microbenchmarks show that broadcast hash joins are currently not performing
well in Comet.
Benchmark query (note that this does not read any decimal columns).
```sql
select ss_sold_date_sk, ss_sold_time_sk, ss_quantity, d_year, d_moy, d_dom
from date_dim join store_sales on d_date_sk = ss_sold_date_sk
where d_year = 2000;
```
Benchmark results (running against sf=100 dataset):
```
AMD Ryzen 9 7950X3D 16-Core Processor
TPCDS Micro Benchmarks: Best Time(ms) Avg Time(ms)
Stdev(ms) Rate(M/s) Per Row(ns) Relative
------------------------------------------------------------------------------------------------------------------------
join_inner 515 527
10 559.0 1.8 1.0X
join_inner: Comet (Scan) 751 770
17 383.4 2.6 0.7X
join_inner: Comet (Scan, Exec) 1089 1099
14 264.6 3.8 0.5X
```
Native plan with metrics from one of the tasks:
```
ProjectionExec: expr=[col_0@4 as col_0, col_1@5 as col_1, col_2@6 as col_2,
col_1@1 as col_3, col_2@2 as col_4, col_3@3 as col_5],
metrics=[output_rows=403302, elapsed_compute=133.629µs]
HashJoinExec: mode=Partitioned, join_type=Inner, on=[(col_0@0, col_0@0)],
metrics=[output_rows=403302, output_batches=256, build_input_batches=1,
input_batches=256, input_rows=2003266, build_input_rows=366,
build_mem_used=15032, build_time=51.757µs, join_time=12.999015ms]
CopyExec, metrics=[output_rows=366, elapsed_compute=10.26µs]
ScanExec: source=[BroadcastExchange (unknown)], schema=[col_0: Int32,
col_1: Int32, col_2: Int32, col_3: Int32], metrics=[output_rows=366,
elapsed_compute=711ns]
CopyExec, metrics=[output_rows=2003266, elapsed_compute=2.142776ms]
FilterExec: col_0@0 IS NOT NULL, metrics=[output_rows=2003266,
elapsed_compute=17.330129ms]
ScanExec: source=[CometScan parquet
spark_catalog.default.store_sales (unknown)], schema=[col_0: Int32, col_1:
Int32, col_2: Int32], metrics=[output_rows=2097152, elapsed_compute=10.135894ms]
```
### Describe the potential solution
_No response_
### Additional context
_No response_
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