Re: Problem Observed in behavior of Create Index Concurrently and Hot Update

On 2012-11-27 14:08:13 -0500, Tom Lane wrote:
> BTW, I was thinking that the DROP INDEX CONCURRENTLY logic needed to be:
>
> 1. Unset indisvalid, commit, wait out all reading transactions.
>
> 2. Unset indisready, commit, wait out all writing transactions.
>
> 3. Unset indislive, commit (with parent table relcache flush),
> wait out all reading-or-writing transactions.
>
> 4. Drop the index.
>
> However, I wonder whether we couldn't combine steps 2 and 3, ie once
> there are no readers of the index go directly to the "dead" state.
> I don't see a need for a period where the index isn't being inserted
> into but is still used for HOT-safety decisions.

I think you're right, that state isn't interesting for anyone.

Greetings,

Andres Freund

--Andres Freund	                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services