Re: [HACKERS] Sync Scan update

2007-02-02 Thread Bruce Momjian
Thread added to TODO for item: * Allow sequential scans to take advantage of other concurrent sequential scans, also called Synchronised Scanning --- Jeff Davis wrote: I have updated my Synchronized Scan patch and have

Re: [HACKERS] Sync Scan update

2007-01-02 Thread Jeff Davis
On Sat, 2006-12-30 at 13:35 -0600, Jim C. Nasby wrote: My current implementation relies on the scans to stay close together once they start close together. If one falls seriously behind, it will fall outside of the main cache trail and cause the performance to degrade due to disk seeking

Re: [HACKERS] Sync Scan update

2007-01-02 Thread Jim C. Nasby
On Tue, Jan 02, 2007 at 09:48:22AM -0800, Jeff Davis wrote: On Sat, 2006-12-30 at 13:35 -0600, Jim C. Nasby wrote: My current implementation relies on the scans to stay close together once they start close together. If one falls seriously behind, it will fall outside of the main cache

Re: [HACKERS] Sync Scan update

2006-12-30 Thread Jim C. Nasby
On Tue, Dec 19, 2006 at 10:37:21AM -0800, Jeff Davis wrote: leader is doing a nested loop and the follower which is just doing a straight sequential scan is being held back? The follower will never be held back in my current implementation. My current implementation relies on the

Re: [HACKERS] Sync Scan update

2006-12-19 Thread Simon Riggs
On Tue, 2006-12-19 at 09:07 -0800, Jeff Davis wrote: I have updated my Synchronized Scan patch and have had more time for testing. Go to http://j-davis.com/postgresql/syncscan-results10.html where you can download the patch, and see the benchmarks that I've run. The results are very

Re: [HACKERS] Sync Scan update

2006-12-19 Thread Jeff Davis
On Tue, 2006-12-19 at 17:43 +, Simon Riggs wrote: On Tue, 2006-12-19 at 09:07 -0800, Jeff Davis wrote: I have updated my Synchronized Scan patch and have had more time for testing. Go to http://j-davis.com/postgresql/syncscan-results10.html where you can download the patch, and see

Re: [HACKERS] Sync Scan update

2006-12-19 Thread Gregory Stark
Simon Riggs [EMAIL PROTECTED] writes: Like to see some tests with 2 parallel threads, since that is the most common case. I'd also like to see some tests with varying queries, rather than all use select count(*). My worry is that these tests all progress along their scans at exactly the same

Re: [HACKERS] Sync Scan update

2006-12-19 Thread Jeff Davis
On Tue, 2006-12-19 at 18:05 +, Gregory Stark wrote: Simon Riggs [EMAIL PROTECTED] writes: Like to see some tests with 2 parallel threads, since that is the most common case. I'd also like to see some tests with varying queries, rather than all use select count(*). My worry is that