Re: How large space will be occupied by mysql for a varchar utf8 column?

[feng guo]

Rick James Wrote:
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> "use a varchar utf8 column other than char utf8
> column" -- I don't under stand what you are
> saying.
>
> 'a' occupies 1 byte in any utf8 VARCHAR or 3 bytes
> in any utf8 CHAR column.
> 'á' occupies 2 bytes in any utf8 VARCHAR or 3
> bytes in any utf8 CHAR column.
> Each Japanese character occupies 3 bytes in any
> utf8 VARCHAR or 3 bytes in any utf8 CHAR column.
>
> 'a' and 'á' can be represented in a CHARACTER SET
> latin1 column, but no Japanese characters can.
> Each takes 1 byte, whether CHAR or VARCHAR.
>
> Chinese has an extra wrinkle, since some
> characters need 4 bytes. To allow for this, you
> need MySQL's utf8mb4.
>
> Back to the question... How much space does text
> take when using VARCHAR with CHARACTER SET
> ut8f?...
>
> * 1 or 2 bytes for a length field
> * 1-3 bytes per character
>
> 'aá' in VARCHAR(10) CHARACTER SET utf8 will take
> the sum of:
> 1 for length
> 1 for 'a'
> 2 for 'á'
> for a total of 4 bytes. That's a lot less than a
> fixed 30 for CHAR(10).
>
> If that fails to explain it adequately, ask your
> question a different way.

I got it,thx!