Re: Faster data type for one-length values

=?ISO-8859-1?Q?Andr=E9_Volpato?= <andre.volpato@ecomtecnologia.com.br> writes:
> I need to store one-length values like '1', '2', '3' or '4' .

> Today, this field is indexed with btree and is of type smallint (int2).
> How much performance will be improved if I change it to "char" (1 byte
> length) ?

The improvement will be zero.  Because of alignment restrictions, you
don't save any space from making an index entry smaller than 4 bytes.

If you have several such fields adjacent in a table row, making them all
narrower can save space, but it doesn't help for standalone index
entries.

            regards, tom lane