1) Does not work becasue MAX() is a grouping function
2) Does work, but gives the same output as in Post #3, eg. Table Scan :(

interesting as mysql.com said using force index makes it so it uses indexes only and requires no table scan>_>

maybe substitute FORCE INDEX with USE INDEX ;)

[sql]select * from post where postid = (select max(postid) from post)[/sql]But i think this will only work for MySQL 4.1 and up.

Otherwise create 2 queries: 1 to get max postid, and 1 to retrieve the row.

Ohh my example is for post table, but should be the same for thread.

Also please notice that you should check with a fully loaded table, since the optimizer might decide that if there are only a few rows, it is more efficient to use a full table scan then to use the index.

If I were you I would check/rebuild your indexes, you should get this ;

[sql]EXPLAIN SELECT * FROM thread ORDER BY threadid DESC LIMIT 1 [/sql]

since there is no condition (WHERE and/or GROUP BY) - this query will be a full index scan

But still could use the index for ordering.