Push the limits past window functions #17347
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datafusion/physical-optimizer/src/limit_pushdown_past_window.rs
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datafusion/physical-optimizer/src/limit_pushdown_past_window.rs
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| if let Some(window) = node.as_any().downcast_ref::<BoundedWindowAggExec>() { | ||
| for expr in window.window_expr().iter() { | ||
| let frame = expr.get_window_frame(); | ||
| if frame.units != WindowFrameUnits::Rows { |
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As far as I can see, we update latest_max only for WindowFrameUnits::Rows cases. If I am not mistaken, it is also valid to update latest_max for WindowFrameUnits::Range and WindowFrameUnits::Groups as longs as end_bound is WindowFrameBound::Preceding(_). I think, we can extend checks to include this use case also.
This should change the plan for following kind of queries
SELECT
c9,
SUM(c9) OVER(ORDER BY c9 ASC RANGE BETWEEN 5 PRECEDING AND 1 PRECEDING) as sum1
FROM aggregate_test_100
LIMIT 5However, we can do this change in subsequent PRs. I think in current form, this PR is correct and we can merge as is. Thanks @avantgardnerio for this PR.
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Good point! I will file a subsequent PR 😄
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Which issue does this PR close?
Rationale for this change
We would like plans with window functions to go faster.
What changes are included in this PR?
A proof-of-concept level optimizer rule push limits past some window functions.
Are these changes tested?
So far only by the existing sqllogictest suite.
Are there any user-facing changes?
Queries with window functions may go faster, particularly if the
TableProvidersupports TopK pushdown.