Bruce Momjian wrote:
> > You don't need to scan the whole page like in the lossy bitmap mode,
> > just all the tuples in the HOT-chain.
> >
> > You need to somehow pass the information that multiple indexes have been
> > used in the bitmap scan to the bitmap heapscan node, so that it knows
> > when the extra checking is required.
>
> That might be confusing because you are going to have some tids that are
> chains, and some that aren't. The hard part is making sure you don't
> include the same tid twice.
>
> Another idea is to set pg_index xid to FrozenTransactionId once the
> VACUUM happens, and if it not frozen, do something special for bitmap
> scans.
Anyway, perhaps we can leave the bitmap scan part to someone more
familiar with that part of the code, like Tom.
HOT is a huge feature, so let's keep working on it. The patch doesn't
have to be 100% on April 1, but we certainly want to try to get as far
as we can by then.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
