Phil Currier escribió: > Inspired by this thread [1], and in particular by the idea of storing > three numbers (permanent ID, on-disk storage position, display > position) for each column, I spent a little time messing around with a > prototype implementation of column storage positions to see what kind > of difference it would make. The results were encouraging: on a table > with 20 columns of alternating smallint and varchar(10) datatypes, > selecting the max() of one of the rightmost int columns across 1 > million rows ran around 3 times faster.
[snipped] I'd expect the system being able to reoder the columns to the most efficient order possible (performance-wise and padding-saving-wise), automatically. When you create a table, sort the columns to the most efficient order; ALTER TABLE ADD COLUMN just puts the new columns at the end of the tuple; and anything that requires a rewrite of the table (ALTER TABLE ... ALTER TYPE for example; would be cool to have CLUSTER do it as well; and do it on TRUNCATE also) again recomputes the most efficient order. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
