On Wed, 7 Feb 2018 09:17:27 +0000 Hick Gunter <[email protected]> escribió:
> SQLite can only use a covering index whose prefix satifies the WHERE and/or > ORDER BY clause(es). > > WHERE x=1 > ORDER BY y > > The WHERE constraint can be handled by an index that starts off with x. > The ORDER BY can be handled by an index that starts off with y. > > SQLite *may* realise that an index on (x,y) satisfies both conditions (within > the fixed x values, y values are already ordered). In that case you would > require the _id field to make it a convering index (x,y,_id). > _id field is always appened at the end of all indexes, it's integer primary key. Your index internally will be (x, y, _id, _id) -- Eduardo <[email protected]> _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
