ASA Database Administration Guide
  Database Options
    Alphabetical list of options

READ_PAST_DELETED option [database]

Function 

Controls server behavior on uncommitted deletes at isolation levels 1 and 2

Allowed values 

ON, OFF

Default 

ON

Description 

If READ_PAST_DELETED is ON (the default), sequential scans at isolation 1 and 2 will skip uncommitted deleted rows. If OFF, sequential scans will block on uncommitted deleted rows at isolation levels 1 and 2 (until the deleting transaction commits or rolls back). This option changes server behaviour at isolation levels 1 and 2.

For most purposes, this option should be left ON. If set to OFF, the blocking behaviour depends on the plan chosen by the optimizer (if there is an index that could possibly be used).