acking-you commented on PR #15694:
URL: https://github.com/apache/datafusion/pull/15694#issuecomment-2800087698
The relevant bug fixes have been completed, and corresponding performance
tests have been conducted. The results show that pre-selection has achieved
significant gains! @Dandandan @alamb
Compare the current optimization with the main branch using `cargo bench
--bench binary_op`. The results are as follows, where fluctuations within ±5%
are considered as no changes.
## Performance Comparison of the AND Logic Group
| Test Case | main | short-and-optimize | Ratio |
Change |
| --------------------- | --------- | ------------------ | ----------- |
---------- |
| all_false | 62.623 ns | 65.923 ns | 0.95x | no
changes |
| one_true_first | 448.69 µs | 195.60 µs | **2.29x** | ↑ ✅
|
| one_true_last | 452.00 µs | 171.91 µs | **2.63x** | ↑ ✅
|
| one_true_middle | 453.12 µs | 173.94 µs | **2.60x** | ↑ ✅
|
| one_true_middle_left | 453.06 µs | 165.70 µs | **2.73x** | ↑ ✅
|
| one_true_middle_right | 459.61 µs | 171.53 µs | **2.68x** | ↑ ✅
|
| all_true_in_and | 450.03 µs | 445.76 µs | 1.01x | no
changes |
## Performance Comparison of the OR Logic Group
| Test Case | main | short-and-optimize | Ratio | Change
|
| ---------------------- | --------- | ------------------ | ----- |
---------- |
| all_true | 61.162 ns | 64.430 ns | 0.95x | no
changes |
| one_false_first | 448.51 µs | 439.92 µs | 1.02x | no
changes |
| one_false_last | 447.38 µs | 453.64 µs | 0.99x | no
changes |
| one_false_middle | 457.79 µs | 447.15 µs | 1.02x | no
changes |
| one_false_middle_left | 452.78 µs | 447.75 µs | 1.01x | no
changes |
| one_false_middle_right | 451.21 µs | 444.23 µs | 1.02x | no
changes |
| all_false_in_or | 449.90 µs | 442.36 µs | 1.02x | no
changes |
## Possible next step(extend to nulls)
### Short-circuit optimization cannot be extended to nulls
The current short-circuit optimization is only applicable to cases without
null values. However, based on the calculation principles of "and" and "or", if
the left-hand side (lhs) evaluates to null, then the final result can only be
determined by continuing to calculate the right-hand side (rhs). Therefore,
optimization for this scenario is not feasible. Below is an example of a
calculation where lhs is null:
```sql
❯ select null and true;
+------------------------+
| NULL AND Boolean(true) |
+------------------------+
| |
+------------------------+
1 row in set. Query took 0.000 seconds.
❯ select null and false;
+-------------------------+
| NULL AND Boolean(false) |
+-------------------------+
| false |
+-------------------------+
1 row in set. Query took 0.000 seconds.
❯ select null or false;
+------------------------+
| NULL OR Boolean(false) |
+------------------------+
| |
+------------------------+
1 row in set. Query took 0.000 seconds.
❯ select null or true;
+-----------------------+
| NULL OR Boolean(true) |
+-----------------------+
| true |
+-----------------------+
1 row in set. Query took 0.000 seconds.
```
### Pre-selection can be extended to include nulls
As I explained earlier:
https://github.com/apache/datafusion/pull/15694#issuecomment-2799010340,
pre-selection can actually be extended to cover cases involving null values.
However, one point needs to be confirmed:
[filter_record_batch](https://docs.rs/arrow-select/54.2.1/src/arrow_select/filter.rs.html#202-205)
will retain rows that are null.
> 4. Combine the left-hand and right-hand boolean arrays to produce the
correct boolean array (modify the positions in the left-hand array marked as
true based on the values from the right-hand array).
Afterward, we only need to modify the fourth step of the pre-selection
process mentioned earlier to complete the extension that supports nulls.
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