Re: TOAST code ignores freespace (was Tweak TOAST code)

On Mon, 2010-05-03 at 23:36 -0400, Jan Wieck wrote:

> Suppose we had something similar to the NULL value bitmap, specifying
> plain or compressed values (not TOAST references), that are moved to a
> shadow tuple inside the toast table. Suppose further we had some
> statistics about how often attributes appear in a qualification (i.e.
> end up in a scan key or scan filter or other parts of the qual
> expression list). Not sure, maybe we even want to know how often or
> seldom an attribute is heap_getattr()'d at all. Those don't need to be
> accurate counts. Small random samples will probably do. ANALYZE could
> evaluate those statistics and adjust the "shadow" storage settings per
> attribute accordingly.
>
> I can imagine many applications, where this would shrink the main
> tuples to almost nothing at all.

Automatic vertical partitioning. Like it.

TODO item for further detailed research.

--
Simon Riggs www.2ndQuadrant.com