I posted some fairly detailed benchmark results for my Synchronized Scan patch and it's interactions with Simon Riggs' Recycle Buffers patch here:
http://j-davis.com/postgresql/patch15-results.html The results are in the form of log files that contain lots of useful debugging info: * log_executor_stats is on (meaning it shows cache hit rate) * the pid, timestamp, and pagenumber being retrieved (for every 5k pages read) * the duration of each scan The results are very positive and quite conclusive. However, the "sync_seqscan_offset" aspect of my patch, which attempts to use pages that were cached before the scan began, did not show a lot of promise. That aspect of my patch may end up being cut. The primary aspect of my patch, the Synchronized Scanning, performed great though. Even the CFQ scheduler, that does not appear to properly read ahead, performed substantially better than plain 8.2.3. And even better, Simon's patch didn't seem to hurt Synchronized Scans at all. Out of the 36 runs I did, a couple appear anomalous. I will retest those soon. Note: I posted the versions of the patches that I used for the tests on the page above. The version of Simon's patch that I used did not apply cleanly to 8.2.3, but the only problem appeared to be in copy.c, so I went ahead with the tests. If this somehow compromised the patch, then let me know. Regards, Jeff Davis ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
