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base repository: postgresql-cfbot/postgresql
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  • 2 commits
  • 16 files changed
  • 2 contributors

Commits on May 30, 2025

  1. Employ EquivalenceClass to adjust ndistinct estimation. 

    Operations like grouping, incremental sort, hash join, memoize, etc., estimate
the number of groups in a source using the statistics of this column
or expression.
Equivalence clauses like 'x=y' obviously reduce the maximum number of distinct
values above the clause evaluation node to the fewest distincts in the 'x'
or 'y' source. Therefore, in estimating the groups number, the planner may
involve this data from the EC.
Identification of proper EC for arbitrary expression seems too expensive
operation. However, having a pathkey gives the planner immediate access to
the EC. Here, a routine to identify proper expression is provided. ndistinct
estimation is cached inside the EM.
    @danolivo
    danolivo authored and Commitfest Bot committed May 30, 2025
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  2. [CF 5754] v0 - Incremental Sort Cost Estimation Instability 

    This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5754

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/2a3c1c60-b38a-4a7f-83ec-940e4abbb6ac@gmail.com
Author(s): Andrei Lepikhov
    Commitfest Bot committed May 30, 2025
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