rewrite approx_median to approx_percentile_cont while planning phase #2262
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@realno @yahoNanJing fyi since you have both worked on this code. I plan to merge this soon if there are no objections. |
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Which issue does this PR close?
Closes #2221 .
Rationale for this change
At this moment optimization rule for "approx_median -> approx_percentile_cont" replacement slightly breaks logical plan (expressions inside of aggregate step don't match its output schema) and it works fine in case of one optimizer pass, but while second optimizer pass projection_push_down rule cleans up approximate_percentile_cont.
What changes are included in this PR?
Suggestion is to move function replacement to planning phase - it seems to be more appropriate (we don't actually need the whole execution plan for this, because it's just rewriting of single expression), and there is no need to adjust all aliases / projections / schemas while optimization phase after replacement.
Are there any user-facing changes?
Fixed execution of queries with approx_median aggregate expression / window function / having filter.