19.07.2019 14:28, liviuslivius wrote: > > what does it mean if below i have twice -> Filter -> Filter?
A bit unusual, but nothing bad. Optimizer for some reason could not combine different booleans together and decided to check them separately. I'd suppose the inner boolean is likely a re-check of the indexed condition, while the outer one is some other non-indexed condition (perhaps the one involving both tables). > Select Expression > -> Filter > -> Nested Loop Join (outer) > -> Filter > -> Table "RDB$DATABASE" as "X RDB$DATABASE" Full Scan > -> Filter > -> Filter > -> Table "RDB$RELATION_FIELDS" as "RF" Access By ID > -> Bitmap > -> Index "RDB$INDEX_4" Range Scan (full match) > Select Expression > -> Filter > -> Nested Loop Join (outer) > -> Filter > -> Table "RDB$RELATIONS" as "R" Full Scan > -> Filter > -> Table "RDB$DATABASE" as "Y RDB$DATABASE" Full Scan Dmitry
