</tgroup>

</table>

<note>

<para>

The <literal>table_len</literal> will always be greater than the sum

of the <literal>tuple_len</literal>, <literal>dead_tuple_len</literal>

and <literal>free_space</literal>. The difference is accounted for by

fixed page overhead, the per-page table of pointers to tuples, and

padding to ensure that tuples are correctly aligned.

</para>

</note>

<para>

<function>pgstattuple</function> acquires only a read lock on the

relation. So the results do not reflect an instantaneous snapshot;