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stats,opt: performance improvements for histograms #39178

Merged
merged 2 commits into from
Aug 1, 2019
Merged

stats,opt: performance improvements for histograms #39178

merged 2 commits into from
Aug 1, 2019

Commits on Aug 1, 2019

  1. stats,opt: move histogram bucket distinct count estimation code 

    This commit moves the code to estimate the number of distinct values
per histogram bucket out of the optimizer and into the stats package.
The purpose of doing this is to remove the overhead of calculating the
number of distinct values per bucket from the critical path of query
planning, and instead perform the calculation offline when initially
generating the histogram.

Release note: None
    @rytaft
    rytaft committed Aug 1, 2019
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  2. opt: performance improvements for histograms 

    This commit improves the performance of histograms in the optimizer
by avoiding allocating and copying the full histogram unless strictly
necessary. Additionally, it changes the code for filtering histograms
to use binary search instead of performing a linear scan.

Release note: None
    @rytaft
    rytaft committed Aug 1, 2019
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    3243046 View commit details
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