Re: Timeline following for logical slots

Craig Ringer wrote:

> It removes the questionable cleanups, fixes the randAccess comment (IMO),

I pushed cleanup separately, including the addition of a few comments
that were documenting the original code. I actually made a mistake in
extracting those, so there's one comment that's actually bogus in that
commit (the candidate_restart_lsn one); it's fixed in the second commit.
Sorry about that. I also introduced XLogReaderInvalReadState here,
called XLogReaderInvalCache originally, since Andres objected to the
"cache" terminology (though you will note that the word "cache" was used
in the original code too.)

> changes the "open a new xlog segment" wording and explains why we don't
> need GetFlushRecPtr/GetXLogReplayRecPtr on replay of a historical timeline.
> I removed the change that did less than a whole page at the XLogRead call
> and instead added a comment explaining it. Fixed the brainfrart with
> candidate_restart_lsn, removed the outdated startptr comment and update and
> the unnecessary XLogReaderInvalCache call after it.
>
> Also renamed src/test/modules/decoding_failover to
> src/test/modules/test_slot_timelines . Best name I could come up with that
> wasn't 1000chars long.
>
> Passes main 'check', contrib/test_decoding check,
> src/test/modules/test_slot_timelines check and src/test/recovery check.
>
> Available attached or at
> https://github.com/2ndQuadrant/postgres/tree/dev/logical-decoding-timeline-following

And pushed this too.

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Álvaro Herrera http://www.2ndQuadrant.com/
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