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

Commits on Mar 9, 2025

  1. Teach Append to consider tuple_fraction when accumulating subpaths. 

    This change is dedicated to more active usage of IndexScan and parameterized
NestLoop paths in partitioned cases under an Append node, as it already works
with plain tables.  As newly added regression tests demonstrate, it should
provide more smartness to the partitionwise technique.

With an indication of how many tuples are needed, it may be more meaningful
to use the 'fractional branch' subpaths of the Append path list, which are
more optimal for this specific number of tuples.  Planning on a higher level,
if the optimizer needs all the tuples, it will choose non-fractional paths.
In the case when, during execution, Append needs to return fewer tuples than
declared by tuple_fraction, it would not be harmful to use the 'intermediate'
variant of paths.  However, it will earn a considerable profit if a sensible
set of tuples is selected.

The change of the existing regression test demonstrates the positive outcome
of this feature: instead of scanning the whole table, the optimizer prefers
to use a parameterized scan, being aware of the only single tuple the join
has to produce to perform the query.

Discussion: https://www.postgresql.org/message-id/flat/CAN-LCVPxnWB39CUBTgOQ9O7Dd8DrA_tpT1EY3LNVnUuvAX1NjA%40mail.gmail.com
Author: Nikita Malakhov <[email protected]>
Author: Andrei Lepikhov <[email protected]>
Reviewed-by: Andy Fan <[email protected]>
Reviewed-by: Alexander Korotkov <[email protected]>
    @danolivo
    danolivo authored and Commitfest Bot committed Mar 9, 2025
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  2. [CF 5361] v3 - Let an Append to consider a tuple fraction when choosi… 

    …ng fractional subpaths

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

https://commitfest.postgresql.org/patch/5361

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/CAPpHfdt2oOoarXM71TNL+Ud71DLG506ScpomfNu0LYciedT3ig@mail.gmail.com
Author(s): Andrei Lepikhov, Nikita Malakhov
    Commitfest Bot committed Mar 9, 2025
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