> Does it Mean that clustered indexes are guarrented to be used for index scan?
> one more thing does clustering means that all future data addition will happen
> in the ordered manner only i mean consecutively in terms of source_id?
No, but clustering a table allows an index scan to visit less pages, and
make less disk seeks. This in turn makes it a better choice for some
queries due to the current layout of tuples on the disk. However, there
are new borderline cases -- just in different places than before.
--
Rod Taylor
