<para>

Finally, all variable-length types must also be passed

by reference. All variable-length types must begin

with a length field of exactly 4 bytes, and all data to

with an opaque length field of exactly 4 bytes, which will be set

by SET_VARSIZE; never set this field directly! All data to

be stored within that type must be located in the memory

immediately following that length field. The

length field contains the total length of the structure,

]]>

</programlisting>

<literal>VARHDRSZ</> is the same as <literal>sizeof(int4)</>, but

<literal>VARHDRSZ</> is the same as <literal>sizeof(int32)</>, but

it's considered good style to use the macro <literal>VARHDRSZ</>

to refer to the size of the overhead for a variable-length type.

Also, the length field <emphasis>must</> be set using the