Andrey Mashenkov created IGNITE-21948:
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Summary: Rethink distributed aggregates converter rules.
Key: IGNITE-21948
URL: https://issues.apache.org/jira/browse/IGNITE-21948
Project: Ignite
Issue Type: Improvement
Components: sql
Reporter: Andrey Mashenkov
Motivation.
We convert LogicalAggregate to map-reduce unconditionally (if possible), which
blows plan search space.
Some plans, which have reduce-phase followed by map-phase without Exchange,
make no sense and will be thrown away after applying cost model (if no - there
is a bug).
Suggestion.
What if we will emit only plans with colocated aggregates?
We can write rules to pushdown colocated aggregate through Exchange via
splitting into map-reduce phases if colocation can't be preserved.
If Exchange can preserve colocation, then aggregate is pushed gown without
splitting.
Let's investigate, if we can eliminate (or significantly decrease number of
plans)
# with Exchange-less Reduce->Map
# map-reduce aggregates on colocated data.
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