22.03.2015 15:21, Thomas Steinmaurer wrote: > I'm confused. ;-) Sorry ;)
> With FB 2.5.2 SC 64-bit on Windows 7 Prof. > > While copying a 18GB database from folder A to B on the same spinning > physical disk at ~33MB/s read + ~33MB/s write, thus 66MB/s total, doing > a select count(*) on that database (8K page size) for a table with ~6Mio > records at a physical disk read rate (according to perfmon) of only > ~7,8MB/s. > > The system has been freshly rebooted, thus the database is not in the > file system cache nor in the FB connection page cache. > > A very naive test, but as I would expect a COUNT(*) with cold caches to > be purely I/O bound, with max. ~7,8MB/s we are far away from nearly > fully utilizing disk I/O. Biggest database in ODS11.x i have right now is just 3.2 GB. Select from largest table (just after OS reboot) shows following numbers: Execute time = 22s 480ms Memory buffers = 512 Reads from disk to cache = 134 023 Page size is 8KB, so it was read at near 46 MB/s. Whole database file (413113 pages) was copied by windows explorer in 65 sec, i.e. at near 49 MB/s read\write or 98 MB/s total. FB 2.5.4, SC Win32, Win7, IO is 2 Seagate HDD's installed in Intel RST RAID 1. Regards, Vlad ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
