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base repository: postgresql-cfbot/postgresql
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head repository: postgresql-cfbot/postgresql
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compare: cf/6118
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  • 2 commits
  • 4 files changed
  • 2 contributors

Commits on Oct 14, 2025

  1. Preserve index stats during ALTER TABLE ... TYPE ... 

    During ALTER TABLE ... TYPE ... on an indexed column, a new index is created and
the old one is dropped. Currently this causes the statistics such as idx_scan,
last_idx_scan, and related counters to be lost.

We can not use pgstat_copy_relation_stats() because the old index is dropped
before the new one is created, so this commit saves the old PgStat_StatTabEntry
and restores it in the new index. This is done by adding a pointer to a hash table
in AlteredTableInfo where the hash key is the partition table Oid. This hash table
stores a list of all the information needed to restore the stats in the right
index.

The stats are saved in ATPostAlterTypeParse() (before the old index is dropped)
and restored in ATExecAddIndex() once the new index is created.

Note that pending statistics (if any) are not preserved, only the
accumulated stats from previous transactions. This is acceptable since the
accumulated stats represent the historical usage patterns we want to maintain.
    @bdrouvotAWS
    bdrouvotAWS authored and Commitfest Bot committed Oct 14, 2025
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  2. [CF 6118] v2 - Preserve index stats during ALTER TABLE ... TYPE ... 

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

https://commitfest.postgresql.org/patch/6118

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/[email protected]
Author(s): Bertrand Drouvot
    Commitfest Bot committed Oct 14, 2025
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