Creates a unique HG index on each Identity/Autoincrement column if the column is not already a primary key.
ON, OFF
Can only be set temporary (for a connection), for a user, or for the PUBLIC group. Takes effect immediately.
OFF
When option is set ON, HG indexes are created on future identity columns. The index can only be deleted if the deleting user is the only one using the table and the table is not a local temporary table.
