Re: One byte integer support

On Thu, 6 Jan 2005, Keith Hankin wrote:

> Is there any way to support one byte integers? I am
> using JDBC and would like to use setByte() method to
> populate values of a single-byte integer valued
> column. I tried defining the column as character(1),
> but I get the error message:
>
> Exception in thread "main"
> org.postgresql.util.PSQLException: ERROR: value too
> long for type character(1)
>
> I don't see how a byte is too long for character(1).

Character is a textual data type, byte is a numeric value so when you set
a byte value of say 145 to a text type you get the string '145' which is
three characters.

Note that character(1) does not take up one byte of space on disk.  It is
a one character field, not one byte.  Multibyte character sets may need
more than one byte to store a single character, so this is variable byte
length field that takes up at least 5 bytes of space.  4 bytes of length
data and then the actual data bytes.

> Is there any data type like MySQL's tinyint?
>

Possibly the system type "char" (needs the quotes), but I have no idea how
that will work with the JDBC driver.  Going with smallint may be the best
thing to do.  Before assuming that a tinyint would actually save you space
you need to make sure you take into account padding and alignment.

Kris Jurka