# (NOT) NULL Indexes

**URL:** <https://forums.percona.com/t/not-null-indexes/858>\
**Category:** Other MySQL® Questions\
**Created:** [July 29, 2008, 5:34pm UTC](https://forums.percona.com/t/not-null-indexes/858 "2008-07-29T17:34:22Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mbor](https://avatars.discourse-cdn.com/v4/letter/m/e47c2d/32.png) [@mbor](https://forums.percona.com/u/mbor)\
**Post date:** [July 29, 2008, 5:34pm UTC](https://forums.percona.com/t/not-null-indexes/858/1 "2008-07-29T17:34:22Z")

</div>

Hi,

I have little question.  
What index should I set on varchar(800) NULL field, if I use it only (beside in SELECT) in WHERE statement with IS (NOT) NULL?  
thx