Hi, I've encountered a performance regression that was introduced in 41c27bc0ff1d3135 (3.19.0 2017-04-18 11:20:19). Following the guidance in "How To Report Bugs Against SQLite" on the wiki, I'm reporting it here.
With these tables and indexes: CREATE TABLE t1 (a TEXT, b TEXT); CREATE TABLE t2 (a TEXT, b TEXT); CREATE INDEX t1_a ON t1 (a); CREATE INDEX t1_b ON t1 (b); CREATE INDEX t2_a ON t2 (a); CREATE INDEX t2_b ON t2 (b); this query now returns very slowly for large amounts of data: SELECT * FROM (SELECT * FROM t1 WHERE a = '123') s1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE a = '123') s2 ON s1.b = s2.b; This is the query plan after the regression: 0|0|0|SEARCH TABLE t1 USING INDEX t1_a (a=?) 0|1|1|SEARCH TABLE t2 USING INDEX t2_b (b=?) And this is the query plan before the regression: 1|0|0|SEARCH TABLE t2 USING INDEX t2_a (a=?) 0|0|0|SEARCH TABLE t1 USING INDEX t1_a (a=?) 0|1|1|SEARCH SUBQUERY 1 AS s2 USING AUTOMATIC COVERING INDEX (b=?) I have verified that the performance problem exists in the latest checkout. Is there any more information I could provide? Thanks for your work on a great tool! Peter. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
