On 04/08/2013 03:22 PM, Max Vlasov wrote:
On Sun, Apr 7, 2013 at 2:12 PM, Max Vlasov <max.vla...@gmail.com> wrote:
On Thu, Apr 4, 2013 at 4:02 PM, Richard Hipp <d...@sqlite.org> wrote:
We would like to encourage people to try out the new code and
report both success and failure.
Not particulary about this draft version, but about my experience with
memory mapped files on Windows If you don't mind .
...
I don't know whether such scenario is possible with sqlite.
Finally I did some tests and didn't not notice anything like that with
creating tables, probably because memory-mapping is not currently for
inserting and updating, so the problem I described seems like not actual.
As for general queries, I have mixed feeling. At least one of my queries
worked 9 seconds on 3.7.17 ddraft instead of 27 seconds with 3.7.16.1. So
the speed progress can be very noticeable in some cases. But as I see the
VFS stopped working transparently in this case. Shouldn't it be so that
xRead and probably xWrite still be in the chain of callings, just doing
memcpy from file-mapping regions instead of calling file routines?
Otherwise many existing vfs filtering solutions (encryption, compression)
won't longer work when memory-mapping is on.
Right. But a VFS is not obliged to support the new xFetch() and
xUnfetch() methods (used to read data from a memory mapped file).
And if it doesn't, SQLite will use xRead() exclusively.
It always uses xWrite() to write - whether mmap is enabled or not.
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