Re: [DOC] Document concurrent index builds waiting on each other - Mailing list pgsql-hackers

From David Johnston
Subject Re: [DOC] Document concurrent index builds waiting on each other
Date
Msg-id 159494240395.807.14927914276731995873.pgcf@coridan.postgresql.org
Whole thread Raw
In response to Re: [DOC] Document concurrent index builds waiting on each other  (James Coleman <jtc331@gmail.com>)
Responses Re: [DOC] Document concurrent index builds waiting on each other
List pgsql-hackers
The following review has been posted through the commitfest application:
make installcheck-world:  not tested
Implements feature:       not tested
Spec compliant:           not tested
Documentation:            tested, passed

James,

I'm on board with the point of pointing out explicitly the "concurrent index builds on multiple tables at the same time
willnot return on any one table until all have completed", with back-patching.  I do not believe the new paragraph is
necessarythough.  I'd suggest trying to weave it into the existing paragraph ending "Even then, however, the index may
notbe immediately usable for queries: in the worst case, it cannot be used as long as transactions exist that predate
thestart of the index build."  Adding "Notably, " in front of the existing sentence fragment above and tacking it onto
theend probably suffices.
 

I don't actually don't whether this is true behavior though.  Is it something our tests do, or could, demonstrate?

It is sorta weird to say "one will not return until all have completed, though, since usually people think return means
completed". That whole paragraph is a bit unclear for the inexperienced DBA, in particular marked ready to use but
isn'tusable.
 

That isn't really on this patch to fix though, and the clarity around concurrent CIC seems worthwhile to add, even if
imprecise- IMO it doesn't make that whole section any less clear and points out what seems to be a unique dynamic.  IOW
Iwould send the simple fix (inline, not a new paragraph) to a committer.  The bigger doc reworking or actual behavioral
improvementsshouldn't hold up such a simple improvement.
 

David J.

The new status of this patch is: Waiting on Author

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