varchar(8) but want to group by only first 4

I have database table with varchar(8) column that is not key. It has
value for example axF12b!h, axF17F!h, axF12893, etc...

axF1 is always the same and I want to goup by this so I can count. How
to do this?

I have more than 3 million record. This is not index key. Will this be
too slow and mysql timeout?

moleskyca1@yahoo.com wrote:
> I have database table with varchar(8) column that is not key. It has
> value for example axF12b!h, axF17F!h, axF12893, etc...
>
> axF1 is always the same and I want to goup by this so I can count. How
> to do this?
>
> I have more than 3 million record. This is not index key. Will this be
> too slow and mysql timeout?

SELECT substr(
column_name
FROM 1
FOR 4
) AS alias_name
FROM table_name
GROUP BY alias_name

on 3 million records it can be slow - can't you add some other
limitations to reduce number of rows to group?? or split it to parts??

moleskyca1@yahoo.com wrote:
> I have database table with varchar(8) column that is not key. It has
> value for example axF12b!h, axF17F!h, axF12893, etc...
>
> axF1 is always the same and I want to goup by this so I can count. How
> to do this?
>
> I have more than 3 million record. This is not index key. Will this be
> too slow and mysql timeout?
>

Yes, it will be slow.

The fact you don't have an index on this column means MySQL will need to
do a table scan. And the fact you're doing a string vs. integer
comparison means it will be even slower.

Adding an index for the column should help.
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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> Adding an index for the column should help.

And you can give a string length with the index, so is you want to group
on the first 4 characters, you can try to add an index with length 4. If
this does not speed up the query, you might try the FORCE clause to
force MySQL using that index, or else the HANDLER statement.

Good luck.