On 31 Oct 2019, at 9:51am, Thomas Kurz <sqlite.2...@t-net.ruhr> wrote:
> I'm using a database with 5 hierarchically strcutured tables using foreign > keys. The largest table contains about 230'000 entries. My problem is that > deleting in this database is extremely slow: Keith found the answer: you don't have the indexes required to make your FOREIGN KEYs run quickly. But I have a question: If you DELETE FROM the child tables first, do you get fast or slow times ? Thee way you're doing it involves a lot of steps as SQlite works its way through the parent table, deletes one row from that, and cascades through the other tables, looking for and deleting related rows from those. SQLite has an optimization for DELETE FROM without a WHERE clause. But I don't know if it's smart enough to realise that if you do that to a parent table, you can also do it to all child tables. Or perhaps its not true and there might be child rows with no parent row, and SQLite is making sure it preserves them. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
