Re: CREATE INDEX and HOT - revised design

"Bruce Momjian"  writes:

> 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.

Since we have all the index info in the relcache we could just skim through
all the indexes when we build the relcache and decide then whether we're
allowed to do HOT updates. That avoids problems if we crash while HOT updates
are disabled.

I think we need to think harder about exactly what test we would perform
against this xid to determine the two relevant tests, 

a) whether to prohibit HOT updates (because the index is "too new")

b) whether to ignore HOT update chains when we use the index (because it's  "too new" and any HOT update chains predate it).

I fear it may imply that we have to keep performing cold updates until the
first vacuum after the xid expires.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com