Does VARCHAR size limit matter?

php mysql database-design varchar
Jane Panda picture Jane Panda · Dec 1, 2010 · Viewed 23.7k times · Source

Possible Duplicate:
Importance of varchar length in MySQL table

When using VARCHAR (assuming this is the correct data type for a short string) does the size matter? If I set it to 20 characters, will that take up less space or be faster than 255 characters?

Answer

ajreal picture ajreal · Dec 1, 2010

Yes, is matter when you indexing multiple columns.

Prefixes can be up to 1000 bytes long (767 bytes for InnoDB tables). Note that prefix limits are measured in bytes, whereas the prefix length in CREATE TABLE statements is interpreted as number of characters. Be sure to take this into account when specifying a prefix length for a column that uses a multi-byte character set.

source : http://dev.mysql.com/doc/refman/5.0/en/column-indexes.html

In a latin1 collation, you can only specify up 3 columns of varchar(255).
While can specify up to 50 columns for varchar(20)

In-directly, without proper index, it will slow-down query speed

In terms of storage, it does not make difference,
as varchar stand for variable-length strings

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