Ühel kenal päeval, E, 2007-12-17 kell 09:20, kirjutas Simon Riggs: > On Sat, 2007-12-15 at 13:32 +0100, Albert Cervera i Areny wrote: > > > Read-Only Tables > > > ---------------- > > > Postgres supports the concept of freezing tuples, so they can live > > > forever within the database without needing further writes. Currently > > > there is no command that will guarantee that a table has been completely > > > frozen. This makes it difficult to reliably write data files to WORM > > > media for longer term archiving. (WORM means Write-Once, Read-Many). > > > It's also a pain having to VACUUM a large table again just because a > > > small number of rows need to be frozen. > > > > > > > I'm not an expert at all, but I'd like to understand this, do you plan that > > READ-ONLY tables wouldn't even store transaction information? That should > > save quite a lot of space. Maybe when the table would be moved to the > > compressed tablespace, MVCC information could be dropped too? Of course > > that > > would avoid future insert & update possibilities though. > > It could, but its a lot of work for little gain. The tuple headers look > like they will compress fairly well, so why bother to remove them at > all?
One place for removing them would be if we do column-stores where there would be one header per column instead of one per tuple. -------------- Hannu ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
