nuno-faria opened a new pull request, #14026:
URL: https://github.com/apache/datafusion/pull/14026
Ensures selections can be pushed past window functions, similarly to what is
already done with aggregations, when possible.
Unlike aggregations, however, extra care must be taken when handling
multiple functions in the same Window operator.
## Which issue does this PR close?
<!--
We generally require a GitHub issue to be filed for all bug fixes and
enhancements and this helps us generate change logs for our releases. You can
link an issue to this PR using the GitHub syntax. For example `Closes #123`
indicates that this PR will close issue #123.
-->
N/A.
## Rationale for this change
<!--
Why are you proposing this change? If this is already explained clearly in
the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand your
changes and offer better suggestions for fixes.
-->
Pushing filters past window functions allows for a more efficient execution,
as data are filtered closer to the root. Optimizers such as the one used by
Postgres already support this optimization. Example:
```sql
CREATE TABLE t (k int, v int);
-- filter is pushed past the window function
EXPLAIN
SELECT *
FROM (
SELECT *, rank() OVER(PARTITION BY k)
FROM t
)
WHERE k = 1; -- filter column is used by the partition key
QUERY PLAN
---------------------------------------------------------
WindowAgg
-> Seq Scan on t
Filter: (k = 1)
-- filter is not pushed past the window function (not used in the
partitioning)
EXPLAIN
SELECT *
FROM (
SELECT *, rank() OVER(PARTITION BY k)
FROM t
)
WHERE v = 1;
QUERY PLAN
---------------------------------------------------------
Subquery Scan on unnamed_subquery
Filter: (unnamed_subquery.v = 1)
-> WindowAgg
-> Sort
Sort Key: t.k
-> Seq Scan on t
```
## What changes are included in this PR?
<!--
There is no need to duplicate the description in the issue here but it is
sometimes worth providing a summary of the individual changes in this PR.
-->
- Added a new match arm handling `LogicalPlan::Window` in
`optimizer/push_down_filters.rs`.
- Added new tests to `optimizer/push_down_filters.rs`.
- Added new tests to `sqllogictest/window.slt`.
## Are these changes tested?
<!--
We typically require tests for all PRs in order to:
1. Prevent the code from being accidentally broken by subsequent changes
2. Serve as another way to document the expected behavior of the code
If tests are not included in your PR, please explain why (for example, are
they covered by existing tests)?
-->
Yes.
## Are there any user-facing changes?
<!--
If there are user-facing changes then we may require documentation to be
updated before approving the PR.
-->
No.
<!--
If there are any breaking changes to public APIs, please add the `api
change` label.
-->
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org
For additional commands, e-mail: github-h...@datafusion.apache.org
