Hello All

Let's say I have two tables:

TABLE_A
ID_A - primary key
FIELD_A - some field

TABLE_B
ID_B - primary key
ID_A - reference to TABLE_A - indexed
FIELD_B - some field - also indexed

then I'd like to update TABLE_A:

UPDATE TABLE_A
SET FIELD_A = some_value
WHERE ID_A IN (SELECT ID_A FROM TABLE_B FIELD_B = some_condition)

When I prepare the statement, Firebird 2.5.1.26166 returns NATURAL plan
for TABLE_A and proper index usage for TABLE_B
Is it correct or am I missing something?
Is there a way to avoid iterating records in some EXECUTE BLOCK statement?

TIA
Marcin