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base repository: postgres/postgres
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head repository: postgrespro/postgres
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compare: clauselist-estimation
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  • 3 commits
  • 10 files changed
  • 2 contributors

Commits on May 22, 2024

  1. Introduce clauselist_selectivity_hook

    @danolivo
    danolivo committed May 22, 2024
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  2. Estimate joins using extended statistics 

    Use extended statistics (MCV) to improve join estimates. In general this
is similar to how we use regular statistics - we search for extended
statistics (with MCV) covering all join clauses, and if we find such MCV
on both sides of the join, we combine those two MCVs.

Extended statistics allow a couple additional improvements - e.g. if
there are baserel conditions, we can use them to restrict the part of
the MCVs combined. This means we're building conditional probability
distribution and calculating conditional probability

    P(join clauses | baserel conditions)

instead of just P(join clauses).

The patch also allows combining regular and extended MCV - we don't need
extended MCVs on both sides. This helps when one of the tables does not
have extended statistics (e.g. because there are no correlations).
    @tvondra @danolivo
    tvondra authored and danolivo committed May 22, 2024
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  3. My Draft

    @danolivo
    danolivo committed May 22, 2024
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