the <structfield>relfrozenxid</> column of a table's

<structname>pg_class</> row contains the freeze cutoff XID that was used

by the last whole-table <command>VACUUM</> for that table. All rows

inserted by transactions with XIDsXIDsolder than this cutoff XID are

inserted by transactions with XIDs older than this cutoff XID are

guaranteed to have been frozen. Similarly,

the <structfield>datfrozenxid</> column of a database's

<structname>pg_database</> row is a lower bound on the unfrozen XIDs