Magnus Hagander wrote:
> But then consider the same table. Except rows are typically updated once or
> twice when they are new, and *then* go read only. And we also have a
> process that at some point deletes *some* old rows (but not all - in fact,
> only a small portion).
>
> In this case, the next INSERT once VACUUM has run is likely to stick a
> "new" row somewhere very "far back" in the table, since there is now free
> space there. This more or less completely ruins the BRIN index usability,
> as the "old" blocks will now contain a single row from a "new" series.
Yeah. When we initially discussed BRIN, there was a mention of allowing
a BRIN index to guide new tuple location -- something like
auto-clustering, if you will. We haven't discussed the exact details
but I think something along those lines is worth considering.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
