I have a table with about 18000 rows and i had no indices defined.

I have a query with about 10 joins of this table and other tables in
DB. It takes very long time. Now i have defined the indices by a
fields which are used in JOINs.

How do i force the DB to build the index for rows which are already in
DB? Because it doesnt look like the query is now using the new indices.

Sorry for my ignorance, i am new to this stuff.

Thanks.