Re: Does VARCHAR2 size matter?

> Also depending on the maximum
> length of the varchar2 variable Oracle requires two length bytes
> instead of one for the column so you would be wasting one byte in
> overhead for every varchar2 over the cut-off length X the number of
> varchar2 variables over this length in the row X the number of rows in
> the table so this can add up to be a signifcant number of bytes.

Actually - after the cut-off point the length of a column is specified by 3bytes - not
2 bytes :-)
If the length byte is FF -> the column contains a NULL

"Mark D Powell" <mark.powell_at_eds.com> wrote in message news:178d2795.0202060536.572afbaa_at_posting.google.com...
> Morten <morten_at_kikobu.com> wrote in message
news:<3C6112F7.1070205_at_kikobu.com>...
> > Hi. What consequences are there when using VARCHAR2(4000) rather
> > than eg. VARCHAR2(500) columns? I'm wondering as VARCHAR2 is variable
> > length, if there are any major performance reasons to keep the
> > fields as small as possible, or if those reasons are more likely to
> > be from a constraining/modelling perspective.
> >
> > Morten
>
> To me, it just seems that if a data item is four characters in length
> then the table column to hold that data item should be defined as four
> characters in length and no more. Also depending on the maximum
> length of the varchar2 variable Oracle requires two length bytes
> instead of one for the column so you would be wasting one byte in
> overhead for every varchar2 over the cut-off length X the number of
> varchar2 variables over this length in the row X the number of rows in
> the table so this can add up to be a signifcant number of bytes.
>
> The documentation used to say the cut-off point was 127 bytes (maximum
> positive integer that can be stored in 1 signed byte).
>
> just IMHO. -- Mark D Powell --
Received on Wed Feb 06 2002 - 07:58:22 CST