mayankshriv opened a new pull request #5798:
URL: https://github.com/apache/incubator-pinot/pull/5798
…sketches and unions.
* In a case with large number of predicates in the
post-aggregation-expression (with OR's), we tend
to end up with a lot of empty sketches (and unions) when not every row
matches each predicate.
This causes an overhead of creating sketches and union'ing them, leading
to potentially huge performance hit.
* In this PR, we improve this behavior by:
- Filtering out empty unions/sketchs when extracting aggregation results.
- Careful merging of results in `merge()` with mininmal unions (only when
necessary).
* We could also perform lazy creation of unions (to ensure that they are not
empty), but that would mean
a hash-map lookup per row. This will penalize the general case when
there's less number of emtpy unions.
So this approach was not taken.
* We saw an overall improvement in latency of about 50%, for cases with:
- Large number of predicates, and
- Large number of segments, and
- Small number of matches per predicate per segment.
## Description
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## Upgrade Notes
Does this PR prevent a zero down-time upgrade? (Assume upgrade order:
Controller, Broker, Server, Minion)
* [ ] Yes (Please label as **<code>backward-incompat</code>**, and complete
the section below on Release Notes)
Does this PR fix a zero-downtime upgrade introduced earlier?
* [ ] Yes (Please label this as **<code>backward-incompat</code>**, and
complete the section below on Release Notes)
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consider:
- New configuration options
- Deprecation of configurations
- Signature changes to public methods/interfaces
- New plugins added or old plugins removed
* [ ] Yes (Please label this PR as **<code>release-notes</code>** and
complete the section on Release Notes)
## Release Notes
If you have tagged this as either backward-incompat or release-notes,
you MUST add text here that you would like to see appear in release notes of
the
next release.
If you have a series of commits adding or enabling a feature, then
add this section only in final commit that marks the feature completed.
Refer to earlier release notes to see examples of text
## Documentation
If you have introduced a new feature or configuration, please add it to the
documentation as well.
See
https://docs.pinot.apache.org/developers/developers-and-contributors/update-document
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