Synchronized Scan WIP patch
От | Jeff Davis |
---|---|
Тема | Synchronized Scan WIP patch |
Дата | |
Msg-id | 1173861778.23443.42.camel@jdavis обсуждение исходный текст |
Ответы |
Re: Synchronized Scan WIP patch
Re: Synchronized Scan WIP patch Re: Synchronized Scan WIP patch |
Список | pgsql-patches |
This is my latest revision of the Sync Scan patch, and it implements the observability as discussed with Simon. Changes: * ss_report_loc() called once per hundred pages rather than once per page * DEBUG messages are a little cleaner and easier to parse, for the sake of analysis after the fact. * DEBUG2 reports a sync scan starting, the relation size in pages, and the location at which the scan starts. * DEBUG2 reports the location of a scan every 50k pages, DEBUG3 every 5k pages (before it was 100k/10k at DEBUG3/DEBUG4, respectively). Numbers are aligned along 5k boundaries to make analysis easier. * GUCs: * sync_seqscan_threshold: fraction of NBuffers for the threshold * sync_seqscan_offset: fraction of NBuffers for the offset * trace_sync_seqscan: will be used in final version of patch to control DEBUG output Sync_scan_offset may be eliminated completely if it's not shown to be useful enough in conjunction with Simon's patch. Sync Scans are still a big win without sync_seqscan_offset. Sync_scan_threshold=<real> may be turned into sync_seqscan=<boolean> with a fixed activation threshold (NBuffers/2 per Simon's suggestion). The reason is that synchronized scans should activate at the same threshold as Simon's scan_recycle_buffers feature. Should we make a "#define BIG_SCAN_THRESHOLD NBuffers/2" to use for both sync_seqscan and for scan_recycle_buffers? Regards, Jeff Davis
Вложения
В списке pgsql-patches по дате отправления: