ignoring NULLs in indexes

[Claude Schneegans]

Hi,

Access has a nice feature that allows creation of indexes WITH IGNORE NULL
which means that records with null values are ignored in the index, so the index will be
shorter and faster to search.

Is there any equivalent for this in MySQL?

Thanks.

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Thanks.

[steve]

> Hi,

Access has a nice feature that allows creation of indexes WITH IGNORE NULL which means that records with null values are ignored in the index, so the index will be shorter and faster to search.

Is there any equivalent for this in MySQL?

I don’t believe so, but others can comment.
http://dev.mysql.com/doc/mysql/en/CREATE_INDEX.html

I presume you could really use this feature if the index field is
sparse (e.g. 2 rows populated out of 1000), and you do not need to do
a query using "where field is null". Otherwise, little to be
gained.

Another thing that might work in a sparse index is limiting the number
of char’s indexed. See link above.

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