On 3/13/2013 8:49 AM, James K. Lowden wrote:
I'm not sure about SQLite, but in principle the query optimizer can often use the base table's index for a derived value. ConsiderA join B on A.a = 1 + B.a or A join B on A.a < sqrt(B.a) An index on B.a is useful to finding the values meeting the criterion.
You seem to expect the optimizer to solve equations - to effectively rewrite the conditions as "B.a = A.a - 1" and "B.a >= 0 and B.a > (case when A.a < 0 then 0 else A.a * A.a end)". I'm pretty sure no major DBMS does that. Definitely SQLite doesn't.
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