mustafasrepo opened a new pull request, #7671:
URL: https://github.com/apache/arrow-datafusion/pull/7671
## Which issue does this PR close?
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Closes #.
## Rationale for this change
Current EnforceDistribution rule produces optimal plans, when physical plan
at its input is single partitioned plan (E.g physical plan doesn't contain any
distribution changing operator). This assumption is valid for datafusion
physical optimizer.
However, others may want to use this rule with their existing plans, that is
already distributed.
In these cases, `EnforceDistribution` used to produce valid plans, generated
plans sometimes were not optimal.
In this PR we extend capabilities of the `EnforceDistribution` rule, so that
even if existing plan is already multi-partitioned, physical plan produced by
`EnforceDistribution` is still optimal.
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## What changes are included in this PR?
The approach to accomplish this as follows.
- Analyze input physical plan to determine requirements at the output of the
query (Such has it has single distribution requirement, or it expects output to
have `a ASC` ordering etc.).
- Add an ancillary operator(`GlobalRequiringExec`) so that requirement of
the query is not lost across rules.
- In the `EnforceDistribution` rule, ignore-remove any distribution changing
operator at its input.
- Then satisfy distribution requirements of the operators using existing
algortihm.
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## Are these changes tested?
Yes, new tests are added. To show that intentionally bad, multi-partitioned
physical plans can be fixed by `EnforceDistribution` rule.
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## Are there any user-facing changes?
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