Your xFilter method is blindly assuming that there is always an argv[0] without checking argc first.
You are incurring an extra "prepare" in your xConnect method, an extra "step" and "column" in your xFilter/xNext methods and an extra "result" in your xColumn function. Doing twice as much work taking twice as long seems quite reasonable. -----Ursprüngliche Nachricht----- Von: sqlite-users [mailto:sqlite-users-boun...@mailinglists.sqlite.org] Im Auftrag von Dimitris Bil Gesendet: Samstag, 22. Oktober 2016 15:31 An: sqlite-users@mailinglists.sqlite.org Betreff: [sqlite] Virtual table acting as wrapper of a regular table Hello, I am trying to create a simple virtual table that acts as wrapper for a normal database table for a specific query. For example, consider that I have tables A and B in my database and the query: select count(A.id) from A CROSS JOIN B where A.id=B.id Now I am using a virtual table acting as wrapper for table B, so I can execute the query select count(A.id) from A CROSS JOIN w where A.id=w.id, where w is the virtual table instance, and get the same result. My problem is that the second query is about 2 times slower. I would normally expect some overhead, but this seems quite slow, so I was wondering if there is something wrong with my code. I am using a prepared statement in connect method for query "select id from B where id=?1" and reset/bind/step in filter method and (if there are more results) step in next method. Here's my code (I am just setting id=0 to denote eof) http://pastebin.com/ce8b4aLL Do you think there's something wrong or it's an unavoidable overhead that comes with the virtual table usage? Are there any chances to improve performance? thanks, Dimitris _______________________________________________ sqlite-users mailing list sqlite-users@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: h...@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. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
