Number of heap blocks scanned. Because the

<link linkend="storage-vm">visibility map</> is used to optimize scans,

some blocks will be skipped without inspection; skipped blocks are

included this total, so that this number will eventually become

includedinthis total, so that this number will eventually become

equal to <structfield>heap_blks_total</> when the vacuum is complete.

This counter only advances when the phase is <literal>scanning heap</>.

</entry>