<symbol>TOAST_TUPLE_THRESHOLD</symbol> bytes (normally 2 kB).

The <acronym>TOAST</acronym> code will compress and/or move

field values out-of-line until the row value is shorter than

<symbol>TOAST_TUPLE_TARGET</symbol> bytes (also normally 2 kB)

<symbol>TOAST_TUPLE_TARGET</symbol> bytes (also normally 2 kB, adjustable)

or no more gains can be had. During an UPDATE

operation, values of unchanged fields are normally preserved as-is; so an

UPDATE of a row with out-of-line values incurs no <acronym>TOAST</acronym> costs if

with <link linkend="sql-altertable"><command>ALTER TABLE ... SET STORAGE</command></link>.

</para>

<para>

<symbol>TOAST_TUPLE_TARGET</symbol> can be adjusted for each table using

<link linkend="sql-altertable"><command>ALTER TABLE ... SET (toast_tuple_target = N)</command></link>

</para>

<para>

This scheme has a number of advantages compared to a more straightforward

approach such as allowing row values to span pages. Assuming that queries are