Erik Jones wrote: > > On Nov 14, 2007, at 10:44 AM, Mike Charnoky wrote: > >> In this usage scenario, doesn't the new HOT (heap only tuples) feature >> of PG8.3 help, in terms of the DB requiring less VACUUM maintenance? >> >> I am similarly performing a huge number of inserts, followed by a huge >> number of updates to fill in a few null fields. The data is indexed by >> insert time. My problem is, selects using that index degrade over time >> as updates are performed, presumably because data is no longer ordered >> sequentially across pages after updates are performed. I was hoping >> that HOT would help here and am actually installing PG8.3 now in order >> to perform some testing... > > Some, what HOT does is keeps index rows from being updated when updates are > made to column values that aren't indexed. The same insert/delete still > happens in the table data. But another thing HOT does is make it possible to vacuum the *page* that the update is taking place on. So if there are dead tuples that nobody needs, they can be removed and the new tuple can be placed there. -- Alvaro Herrera http://www.advogato.org/person/alvherre "Use it up, wear it out, make it do, or do without" ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
