I'm using this query but it is really really slow

```
   INSERT INTO a (b,c,d,e,f,g,h,i) SELECT b,c,d,e,f,g,h,i FROM z WHERE b NOT IN (SELECT b FROM a)

```

What is does is find all records where b is not in table "a" from table z and importing it into table a.

Its really really slow and keeps timing. Is there away to make it quicker?

Thank-you
BigThings

P.s.