Mark Kirkwood wrote: > Christopher Kings-Lynne wrote: > >>The point here is that if tuples require 50 bytes, and there are 20 > >>bytes free on a page, pgstattuple counts 20 free bytes while FSM > >>ignores the page. Recording that space in the FSM will not improve > >>matters, it'll just risk pushing out FSM records for pages that do > >>have useful amounts of free space. > > > >Maybe an overloaded pgstattuple function that allows you to request FSM > >behavior? > > That's a nice idea - could also do equivalently by adding an extra > column "usable_free_space" or some such, and calculating this using FSM > logic.
The current pgstattuple function scans the whole table, so I don't think this is a good idea. Re: the overloaded function, I think the behaviors are different enough to merit a separate function, with a different name. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
