Re: CREATE INDEX and HOT - revised design

On Wed, 2007-03-21 at 10:47 -0400, Bruce Momjian wrote:

> A different idea is to flag the _index_ as using HOT for the table or
> not, using a boolean in pg_index. The idea is that when a new index is
> created, it has its HOT boolean set to false and indexes all tuples and
> ignores HOT chains. Then doing lookups using that index, the new index
> does not follow HOT chains. We also add a boolean to pg_class to
> indicate no new HOT chains should be created and set that to false once
> the new index is created. Then, at some later time when all HOT chains
> are dead, we can enable HOT chain following for the new index and allow
> new HOT chains to be created.

"enable HOT chain following" would require us to hold an
AccessExclusiveLock on the index.

We know that solution exists, the question is: at what point would we
ever request that lock? Or would we just wait until that lock is next
taken before enabling it, giving the user no control over when its
taken? A separate DDL command would be effectively the same as what
Pavan has recently suggested.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com