Hello Richard, How much do you map at a time? I've virtually abandoned memory mapped files in Win32 because of address space limitations. There's a 2 GB address space limit in Win32 (most of the time) so, if the combination of allocated RAM and memory mapped file size bump into the limit, the memory map will fail. Win64 doesn't have this limit. It'll fail if it can't get a contiguous block of address space too.
C Thursday, April 4, 2013, 8:02:34 AM, you wrote: RH> By making use of memory-mapped I/O, the current trunk of SQLite (which will RH> eventually become version 3.7.17 after much more refinement and testing) RH> can be as much as twice as fast, on some platforms and under some RH> workloads. We would like to encourage people to try out the new code and RH> report both success and failure. Snapshots of the amalgamation can be RH> found at RH> http://www.sqlite.org/draft/download.html RH> Links to the relevant documentation can bee seen at RH> http://www.sqlite.org/draft/releaselog/3_7_17.html RH> The memory-mapped I/O is only enabled for windows, linux, mac OS-X, and RH> solaris. We have found that it does not work on OpenBSD, for reasons we RH> have not yet been able to uncove; but as a precaution, memory mapped I/O is RH> disabled by default on all of the *BSDs until we understand the problem. RH> The biggest performance gains occur on windows, mac, and solaris. The new RH> code is also faster on linux, but not by as big a factor. The speed RH> improvement is also heavily dependent upon workload. Some operations can RH> be almost twice as faster. For others, there is no measurable speed RH> improvement. RH> Your feedback on whether or not the new code is faster for you, and whether RH> or not it even works for you, is very important to us. Thanks for giving RH> the new code a try. -- Best regards, Teg mailto:t...@djii.com _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
