Dandandan opened a new pull request #213:
URL: https://github.com/apache/arrow-datafusion/pull/213
# Which issue does this PR close?
Closes #206
# Rationale for this change
`LIMIT 0` can be used to test a certain query / get the schema from a query
or the value `0` can result from a constant folding. This rule replaces the
limit 0 by an empty plan, saving time in the physical planner (no need to read
metadata/statistics/partitions etc) and there is no need to produce a single
batch.
# What changes are included in this PR?
A new optimization pass to replace `LIMIT 0` in the `LogicalPlan` with an
`EmptyRelation`, with the same schema.
# Are there any user-facing changes?
No breaking changes, should only be faster in some cases.
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