Re: CREATE INDEX and HOT (was Question: pg_classattributes and race conditions ?)

On 3/19/07, Pavan Deolasee  wrote:
> Yeah, I think CREATE INDEX CONCURRENTLY is much easier to solve. Though
> I am not completely convinced that we can do that without much changes
> to CREATE INDEX CONCURRENTLY logic. For example, I believe we still
> need to lock out HOT-updates before we start CREATE INDEX CONCURRENTLY.
> Otherwise we might end up creating two paths to the same tuple in
> the new index.
>
> Say, we have a table with two columns (int a, int b). We have an
> index on 'a' and building another index on 'b'. We got a tuple
> (10, 20) in the heap. In the first phase of CREATE INDEX CONCURRENTLY,
> this tuple would be indexed. If the tuple is HOT-updated to (10, 30)
> before the first phase ends, the updated tuple would again get
> indexed in the second phase. This would lead to two paths to the
> latest visible tuple from the new index.

just a thought...can you disable HOT on the fly?  why not disable hot
updates completely during these types of operations?.

merlin