Is the covering index scan optimization enabled in the mentioned
amalgamation?
For large datasets it can speed up the queries a lot.
l.
On 09/10/12 20:19, Richard Hipp wrote:
SUMMARY:
If you have a complex application that uses SQLite, please test your
application with the SQLite amalgamation found at
http://www.sqlite.org/sqlite3-20121009.zip and report to me (via private
email) whether or not you encounter any problems.
DETAILS:
We have recently made a number of significant enhancements to the query
optimizer in SQLite. In particular, the latest code does a much better job
of recognizing when ORDER BY clauses can be satisfied by careful selection
of indices and scan orders and without having to do any sorting. This
optimization can result in significant performance improves for queries
with large result sets.
The current implementation has already been well tested:
(1) All legacy tests pass
(2) 100% branch test coverage
(3) The Fossil server that hosts the SQLite source code is using the latest
SQLite
(4) This email is being composed on an instance of Firefox Nightly that is
running the latest SQLite code
However, with such extensive changes to the query optimizer there is a
heightened risk of missing obscure corner cases in which SQLite omits
sorting for an ORDER BY clause when the sort is actually needed, resulting
in output appearing in the wrong order. You can help reduce this risk, and
help us to ensure that the forthcoming SQLite version 3.7.15 is
trouble-free, by compiling the SQLite amalgamation snapshot found at
http://www.sqlite.org/sqlite3-20121009.zip into your application and then
testing your application to verify that it is still working correctly. If
you find any problems, please let me know. If your application continues
to work normally (though perhaps a little faster) I would appreciate
hearing from you then too.
I are especially interested in hearing from people whose applications
contain large schemas, descending indices, and complex joins containing
ORDER BY clauses with multiple terms and a mixture of ASC and DESC.
Thank you for your help.
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