On Mon, Feb 22, 2010 at 7:59 PM, Andreas Kretschmer <akretsch...@spamfence.net> wrote: > Daniele Varrazzo <daniele.varra...@gmail.com> wrote: > >> Hello, >> >> at Prato PgDay in 2007 I remember hearing in a speech about a (then >> yet to come) "seqscan piggyback" feature, allowing concurrent >> sequential scans to use the same disk reads. I've now googled for info >> about this feature, but I found nothing conclusive (e.g. [1], [2] - >> which I don't know where is linked).
> I think, you means this: > > Concurrent large sequential scans can now share disk reads (Jeff Davis) > > This is accomplished by starting the new sequential scan in the middle > of the table (where another sequential scan is already in-progress) and > wrapping around to the beginning to finish. This can affect the order of > returned rows in a query that does not specify ORDER BY. The > synchronize_seqscans configuration parameter can be used to disable this > if necessary > > Source: > http://www.postgresql.org/docs/current/interactive/release-8-3.html Thank you very much (and thanks to Bruce too). This is the feature and I'm checking it works "out of the box" on PG 8.3 -- Daniele -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
