On Fri, Sep 25, 2009 at 8:53 AM, Scott Carey <sc...@richrelevance.com> wrote: > That won't work well anyway because the postgres shared_buffers dos not cache > things that are sequentially scanned (it uses a ring buffer for each scan). > So, for > any data that is only accessed by sequential scan, you're relying on the OS > and > the disks. If you access a table via index scan though, all its pages will > go through > shared_buffers.
Does it doe this even if the block was already in shared_buffers? That seems like a serious no-no to me to read the same block into different buffers. I thought that the sequential scan would have to break stride when it encountered a block already in buffer. But I haven't looked at the code, maybe I am over analogizing to other software I'm familiar with. Jeff -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
