Seems the correct code is already generated... asql> explain select rowid from x where 1=?; addr opcode p1 p2 p3 p4 p5 comment ---- ------------- ---- ---- ---- ------------- -- ------------- 0 Trace 0 0 0 00 NULL 1 Integer 1 2 0 00 NULL 2 Variable 1 3 0 00 NULL 3 Eq 3 1 2 72 NULL 4 IfNot 1 12 1 00 NULL 5 Goto 0 14 0 00 NULL 6 OpenRead 0 2 1 0 00 x 7 Rewind 0 12 0 00 NULL 8 IfNot 1 11 1 00 NULL 9 Rowid 0 4 0 00 NULL 10 ResultRow 4 1 0 00 NULL 11 Next 0 8 0 01 NULL 12 Close 0 0 0 00 NULL 13 Halt 0 0 0 00 NULL 14 Transaction 1 0 0 00 NULL 15 VerifyCookie 1 1 1 00 NULL 16 TableLock 1 2 0 x 00 NULL 17 Goto 0 6 0 00 NULL
-----Urspr?ngliche Nachricht----- Von: Mark Lawrence [mailto:nomad at null.net] Gesendet: Freitag, 12. Juni 2015 11:37 An: sqlite-users at mailinglists.sqlite.org Betreff: [sqlite] Contstant WHERE terms still require table scan? I'm wondering if it would be possible to optimize the query planner for situations where one of the WHERE clauses is a constant that evaluates to false? CREATE TABLE x( id INTEGER PRIMARY KEY ); EXPLAIN QUERY PLAN SELECT x.id FROM x WHERE 1=0 ; -- selectid order from detail -- ---------- ---------- ---------- ------------ -- 0 0 0 SCAN TABLE x This would potentially allow me to shortcut some largish UNION statements. Mark. -- Mark Lawrence Home: +41 44 520 12 59 Mobile: +41 76 796 65 68 _______________________________________________ sqlite-users mailing list sqlite-users at mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___________________________________________ Gunter Hick Software Engineer Scientific Games International GmbH FN 157284 a, HG Wien Klitschgasse 2-4, A-1130 Vienna, Austria Tel: +43 1 80100 0 E-Mail: hick at scigames.at This communication (including any attachments) is intended for the use of the intended recipient(s) only and may contain information that is confidential, privileged or legally protected. Any unauthorized use or dissemination of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by return e-mail message and delete all copies of the original communication. Thank you for your cooperation.
