Hello All,

In FB.1.5.xx

DELETE FROM TICKETITEMS WHERE TICKET_UNIQUENUM
NOT IN (SELECT TICKET_UNIQUENUM FROM TICKETS);

executes in a fraction of a second, since it uses

PLAN (TICKETS INDEX (RDB$PRIMARY15))
PLAN (TICKETITEMS NATURAL)

or

DELETE FROM TICKETITEMS ti WHERE ti.TICKET_UNIQUENUM
NOT IN (SELECT t.TICKET_UNIQUENUM FROM TICKETS t);

executes in the same fraction of a second and uses

PLAN (T INDEX (RDB$PRIMARY15))
PLAN (TI NATURAL)

===================================================

However in FB.2.0.0.0 the same delete SQL

DELETE FROM TICKETITEMS WHERE TICKET_UNIQUENUM
NOT IN (SELECT TICKET_UNIQUENUM FROM TICKETS);

execution takes forever, since it selects

PLAN (TICKETS NATURAL)
PLAN (TICKETITEMS NATURAL)

or

DELETE FROM TICKETITEMS ti WHERE ti.TICKET_UNIQUENUM
NOT IN (SELECT t.TICKET_UNIQUENUM FROM TICKETS t);

uses

PLAN (T NATURAL)
PLAN (TI NATURAL)

===================================================

Best Regards
Hans