On Wed, Nov 27, 2013 at 9:35 AM, Clemens Ladisch <clem...@ladisch.de> wrote:
> veeresh kumar wrote: > > I see that in release history for 3.8.1 below item. > > "Estimate the sizes of table and index rows and use the smallest > applicable B-Tree for full scans and "count(*)" operations." > > > > Does it mean that performance of count(*) has been improved in 3.8.1 > > Yes. > > > and if yes by how much? > > That depends on how much the rows of your smallest index are smaller > than the rows of the table. > What about vtables? How does SQLite estimate the size of table and index rows for vtables? Sometimes vtables are based on native containers which know their size, thus it's an O(1) op, but the vtable has no way to communicate that size to the engine to bypass an O(N) full scan? Any chance the vtable API would allow such shortcuts? Thanks, --DD _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
