On 18 Feb 2019, at 4:41pm, Charles Leifer <colei...@gmail.com> wrote:
> Simon, I appreciate that, but your comment seems to contradict the example I > provided, as well as the example Dr. Hipp provided. Am I misunderstanding? SQLite can compare two comparators. In Dr. Hipp's example the index says "extra IS NOT NULL" and the WHERE clause says "WHERE extra>?1" SQLite knows that for extra to be bigger than a number -- any number -- extra cannot be NULL. So it can deduce that it can use that partial index. That's what Dr. Hipp wrote. However, suppose you had a partial index that keyed on "extra > 4" and your SELECT had the clause "WHERE extra > ?1" The parameter might be set to 7. You and I know that this means SQLite could use the partial index. But SQLite will not compare the 7 and the 4 and decide it can use the partial index. It does not know that 7 is greater than 4, because it doesn't look at the parameter's value before doing its optimization. Simon. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
