Kevin Grittner wrote: > David Rowley <david.row...@2ndquadrant.com> wrote:
> > 5. Dependant Aggregates > > > Item 5 makes items 1-4 a bit more complex as with this item > > there's opportunity for very good performance improvements by > > allowing aggregates like AVG(x) also perform all the required > > work to allow SUM(x) and COUNT(x) to be calculated for "free" in > > a query containing all 3 aggregates. > > Not only CPU is saved, but the optimizations for materialized views > would require the aggregate function's transition state to be saved > in each row, and the duplicate state information among these > functions would be a waste of space. Uh, this also requires serialization and deserialization of non- finalized transition state, no? -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
