wForget opened a new pull request, #57073:
URL: https://github.com/apache/spark/pull/57073
<!--
Thanks for sending a pull request! Here are some tips for you:
1. If this is your first time, please read our contributor guidelines:
https://spark.apache.org/contributing.html
2. Ensure you have added or run the appropriate tests for your PR:
https://spark.apache.org/developer-tools.html
3. If the PR is unfinished, add '[WIP]' in your PR title, e.g.,
'[WIP][SPARK-XXXX] Your PR title ...'.
4. Be sure to keep the PR description updated to reflect all changes.
5. Please write your PR title to summarize what this PR proposes.
6. If possible, provide a concise example to reproduce the issue for a
faster review.
7. If you want to add a new configuration, please read the guideline first
for naming configurations in
'core/src/main/scala/org/apache/spark/internal/config/ConfigEntry.scala'.
8. If you want to add or modify an error type or message, please read the
guideline first in
'common/utils/src/main/resources/error/README.md'.
-->
### What changes were proposed in this pull request?
This PR adds support for a new `REBALANCE_BY_SIZE` SQL hint.
The new hint works like `REBALANCE`, but accepts an optional advisory
partition size in bytes as its first parameter, followed by optional partition
columns. For example:
```sql
SELECT /*+ REBALANCE_BY_SIZE(134217728) */ * FROM t;
SELECT /*+ REBALANCE_BY_SIZE(134217728, c) */ * FROM t;
```
The implementation resolves `REBALANCE_BY_SIZE` to `RebalancePartitions`
with `optAdvisoryPartitionSize`, so AQE can use the hint-specific advisory
partition size for the rebalance shuffle.
### Why are the changes needed?
A common use case of `REBALANCE` is small file control before writing query
results. Users may want to insert a rebalance before the write and set a larger
advisory partition size for the final output stage, so each output
partition/file has a reasonable target size.
Today this requires changing the session-level
`spark.sql.adaptive.advisoryPartitionSizeInBytes` configuration. That is too
coarse-grained because it may also affect preceding AQE stages, including
shuffle coalescing and read/computation parallelism before the final write
stage.
`REBALANCE_BY_SIZE` provides a query-level way to apply a target partition
size only to the rebalance shuffle, which is useful for output file size
control without changing the advisory size used by earlier stages.
### Does this PR introduce _any_ user-facing change?
Yes, a new `REBALANCE_BY_SIZE` hint.
### How was this patch tested?
Added unit tests
### Was this patch authored or co-authored using generative AI tooling?
Docs and tests generated-by: Codex (GPT-5)
--
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: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
