Does it revert back to slower speed after dropping the index? Can you compare the EXPLAIN output produced with and without the index?
There is no difference on my machine (Version 3.7.14); if yours behaves the same way then whatever changes speed is definitely not because SQLite is doing something differently. asql> create temp table t (x integer primary key asc, y,z); asql> .explain asql> explain select * from t where rowid=15; addr opcode p1 p2 p3 p4 p5 comment ---- ------------- ---- ---- ---- ------------- -- ------------- 0 Trace 0 0 0 00 NULL 1 Integer 15 1 0 00 NULL 2 Goto 0 12 0 00 NULL 3 OpenRead 0 2 1 3 00 t 4 MustBeInt 1 10 0 00 NULL 5 NotExists 0 10 1 00 pk 6 Rowid 0 3 0 00 NULL 7 Column 0 1 4 00 t.y 8 Column 0 2 5 00 t.z 9 ResultRow 3 3 0 00 NULL 10 Close 0 0 0 00 NULL 11 Halt 0 0 0 00 NULL 12 Transaction 1 0 0 00 NULL 13 VerifyCookie 1 1 0 00 NULL 14 TableLock 1 2 0 t 00 NULL 15 Goto 0 3 0 00 NULL asql> explain select * from t where x=15; addr opcode p1 p2 p3 p4 p5 comment ---- ------------- ---- ---- ---- ------------- -- ------------- 0 Trace 0 0 0 00 NULL 1 Integer 15 1 0 00 NULL 2 Goto 0 12 0 00 NULL 3 OpenRead 0 2 1 3 00 t 4 MustBeInt 1 10 0 00 NULL 5 NotExists 0 10 1 00 pk 6 Rowid 0 3 0 00 NULL 7 Column 0 1 4 00 t.y 8 Column 0 2 5 00 t.z 9 ResultRow 3 3 0 00 NULL 10 Close 0 0 0 00 NULL 11 Halt 0 0 0 00 NULL 12 Transaction 1 0 0 00 NULL 13 VerifyCookie 1 1 0 00 NULL 14 TableLock 1 2 0 t 00 NULL 15 Goto 0 3 0 00 NULL asql> create index t_x on t(x); asql> explain select * from t where x=15; addr opcode p1 p2 p3 p4 p5 comment ---- ------------- ---- ---- ---- ------------- -- ------------- 0 Trace 0 0 0 00 NULL 1 Integer 15 1 0 00 NULL 2 Goto 0 12 0 00 NULL 3 OpenRead 0 2 1 3 00 t 4 MustBeInt 1 10 0 00 NULL 5 NotExists 0 10 1 00 pk 6 Rowid 0 3 0 00 NULL 7 Column 0 1 4 00 t.y 8 Column 0 2 5 00 t.z 9 ResultRow 3 3 0 00 NULL 10 Close 0 0 0 00 NULL 11 Halt 0 0 0 00 NULL 12 Transaction 1 0 0 00 NULL 13 VerifyCookie 1 2 0 00 NULL 14 TableLock 1 2 0 t 00 NULL 15 Goto 0 3 0 00 NULL -----Urspr?ngliche Nachricht----- Von: sqlite-users-bounces at mailinglists.sqlite.org [mailto:sqlite-users-bounces at mailinglists.sqlite.org] Im Auftrag von ??? Gesendet: Montag, 14. Dezember 2015 14:06 An: SQLite mailing list Betreff: [sqlite] Is rowid the fastest? You said that "You are probably falling into the cache effect trap again. There is no point in indexing on the primary key, it only wastes space and CPU cycles ". I do not agree with you. let me tell you why. Before I retrieve by index which created for primary key. The speed of retrieve by rowid is very stable(for a long time). Once I retrieve by index , the stable will broken and the speed is faster than its before. I think you could try it. ___________________________________________ 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.
