On Fri, 2005-09-30 at 09:42 -0400, Robert Treat wrote:
> I like how you separated the two concepts here, but didn't like how
> titled Lance... how about:
Well, I think Josh or Lance should step in here. You're right, I only
meant to separate the two concepts.
> > ! Bitmap Scan: indexes can be dynamically converted to
> > bitmaps in memory, giving up to 20x faster index performance on
> > ! complex queries against against very large tables. Bitmap Scan
> > ! also greatly reduces the need for multi-column indexes.
>
> I think we need to be a little more explicit about why this is a good
> thing.
> Bitmap Scan: indexes can be dynamically converted to
> bitmaps in memory, giving up to 20x faster index performance on
> complex queries against against very large tables. This helps simplify
> database management by greatly reducing the need for multi-column
> indexes.
...This can also simplify database management by greatly reducing
the number of multi-column indexes required for an application.
> > ! Table Partitioning: in version 8.1, the query planner is now
> > ! able to avoid scanning whole sections of a large table without
> > ! needing to utilise indexes using a technique known as
> > ! Constraint Exclusion.
> >
I'll think of a short para.
Best Regards, Simon Riggs