On Wed, Nov 30, 2011 at 8:02 AM, Greg Smith <greg@2ndquadrant.com> wrote:
>>>> Except in the sections talking about locking
>>>> internals we don't talk about "shared locks on virtual transactions
>>>> identifiers" we just talk about waiting for a transaction to complete.
> What I cannot agree with is that idea that the implementation details I
> suggested documenting should not be.
What I'm suggesting is translating things like "shared locks on
virtual transaction identifiers" into what that means for users.
Namely saying something like "waiting for a transaction to complete".
Given your confusion it's clear that we have to explain that it will
wait one by one for each transaction that was started before the index
was created to finish. I don't think we need to explain how that's
implemented. If we do it should be set aside in some way, something
like "(see virtual transaction id locks in <href...>)".
I just want to keep in mind that the reader here is trying to
understand how to use create index concurrently, not understand how
Postgres's locking infrastructure works in general.
--
greg