Question

I realize that the exact question has been asked before on stack overflow with only a vaguely conclusive answer: link

So here it is again.

Table A: Has an integer column which is nullable, along with an index.
Query:

SELECT * 
FROM table 
WHERE column IS NULL 
LIMIT 10;

Will an index be used, or will mysql do a full table scan until it has found 10 entries?

Answer 1

i think this should be helpful:

http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html

A search using col_name IS NULL employs indexes if col_name is
indexed.