Simon, On 3/13/07 2:37 AM, "Simon Riggs" <[EMAIL PROTECTED]> wrote:
>> We're planning a modification that I think you should consider: when there >> is a sequential scan of a table larger than the size of shared_buffers, we >> are allowing the scan to write through the shared_buffers cache. > > Write? For which operations? I'm actually just referring to the sequential scan "writing into" the shared buffers cache, sorry for the "write through" :-) > I was thinking to do this for bulk writes also, but it would require > changes to bgwriter's cleaning sequence. Are you saying to write say ~32 > buffers then fsync them, rather than letting bgwriter do that? Then > allow those buffers to be reused? Off topic, but we think we just found the reason(s) for the abysmal heap insert performance of pgsql and are working on a fix to that as well. It involves two main things: the ping-ponging seeks used to extend a relfile and the bgwriter not flushing aggressively enough. We're hoping to move the net heap insert rate from 12MB/s for a single stream to something more like 100 MB/s per stream, but it may take a week to get some early results and find out if we're on the right track. We've been wrong on this before ;-) - Luke ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
