There's a number of major features all coming together over the next
weeks, so I wanted to raise some awareness of possible areas of
interaction. My concern is more than just "will multiple patches apply
together?", but extends into whether the features interact with each
other with synergy, ignore each other or have negative impact.

The projects that concern me are the following internals projects

Plan Invalidation
Autovacuum changes
Bitmap indexes
GIT indexes
Dead Space Map (DSM)
HOT Updating
Updateable cursors
Restartable VACUUM

The potential interactions as I understand them are these: I'm not
saying this list is either complete or accurate; checking whether it is
or not is exactly the reason for this post.

Anyway, just trying to raise awareness to look for potential issues.

        Syntax changes only, no impact on other projects mentioned.

        Used to be some conflicts at patch level, now gone?
        Positive impact on GIT performance
        heap_check_hotupdate() test can performed in planner, so
        will no longer be a heap function
        HOT updates need not be logged, since they will be cleared
        by retail VACUUMs
        Potential issue with chilling tuples during CREATE INDEX
        HOT will change how UPDATEs are reported to pg_stat, by
        adding additional fields.
        Should tidscan follow chain to correct tuple? That seems to
        change current behaviour even if it might be useful.
Plan Invalidation
        No known changes, other than the integrations already mentioned

Autovacuum changes
        Is implementing new forms of VACUUM: VACUUM and VACUUM ALL.
        Does reporting of row stats change? 

Bitmap indexes
        Do we need both? I think yes, but need to see some info on
        when crossover occurs between two index methods.

Restartable VACUUM
        Interactions with DSM?
        Must use full cycles only

  Simon Riggs             

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