The scheduled release of SQLite version 3.7.6 is mid-April. We are still
two months away. However, version 3.7.6 will contain a lot of pent-up
changes and so your advance testing of this release will be appreciated.
The latest pre-3.7.6 code can be found here:
http://www.sqlite.org/draft/download.html
And sketchy information about the changes added (so far) can be seen here:
http://www.sqlite.org/draft/releaselog/3_7_6.html
Of particular concern in 3.7.6 are some tweaks we've done to the query
planner. The query planner is the part of SQLite that decides on the best
and fastest algorithm to use to satisfy your queries. SQLite uses a
cost-based query planner. In other words, it tries to estimate the CPU and
disk I/O load used by various alternative algorithms and it selects the
algorithm with the lowest estimated cost. The problem with this approach is
that the cost really is an estimate based on incomplete information, and so
it sometimes comes out wrong. The cost functions for 3.7.6 have been
enhanced to be more accurate (we believe) particularly if SQLite is compiled
using SQLITE_ENABLE_STAT2 and you run ANALYZE on your database files to
gather statistics. But there could be instances where the cost estimates
are not as good as before, resulting in performance regressions.
So, if you have the ability to download an early snapshot of SQLite 3.7.6
and compile it into your application for performance testing purposes, we
would really appreciate it if you would do so. And do so sooner rather than
later so that we can have plenty of time to fix an issues you discover prior
to the 3.7.6 release. If the query planner in 3.7.6 improves the
performance of your application, we'd also like to hear about that too.
I'll try to post snapshots of 3.7.6 on a regular basis so that you can
download and compile a fairly recent version at any time. Please pester me
if I forget.
Thanks for your help.
--
D. Richard Hipp
d...@sqlite.org
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