Simon Slavin <slav...@bigfraud.org> wrote: > On 8 Apr 2011, at 2:34pm, Vadim Smirnov wrote: > >> Tbl1(id1 INTEGER, id2 INTEGER, str TEXT) 2 records >> Tbl2(id INTEGER, Tbl1_id INTEGER, str TEXT) ~5000 records >> And SQL-query: SELECT Tbl2.id, MY_FUNC(Tbl1.str, Tbl2.str) FROM Tbl2 JOIN >> Tbl1 ON Tbl1.id1=Tbl2.Tbl1_id WHERE Tbl2.id>1000 AND >> Tbl1.id2=1 LIMIT 50 We expected that MY_FUNC would be evaluated 50 times at >> most, but it appeared 10000! >> Why so? > > Your SELECT consists of a JOIN which tells SQLite to try every combination of > one record from each table. For each combination > it checks to see that all the conditions you gave are true.
But the custom function is not involved in the WHERE clause. There doesn't seem to be any reason to call it for rows that aren't going to be returned. -- Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
