We can also implement the same for index tuples.....
On Dec 17, 2007 1:10 PM, Gokulakannan Somasundaram <gokul007@gmail.com> wrote:
Hi, Currently we check for the existence of NULL values in the tuple and we set the has_null flag. If the has_null flag is present, the tuple will be storing a null bitmap. What i propose is
a) By modifying the functions, heap_form_tuple and heap_fill_tuple, we can check whether all the nulls are trailing nulls. If all the nulls are trailing nulls, then we will not set the has_null flag and we will not have the null bitmap with the tuple.
b) While selecting the tuple, we will check whether the tuple offset equals / exceeds the length of the tuple and then mark the remaining attributes of the tuple as null. To be exact, we need to modify the slot_deform_tuple in order to achieve the same.
This may not give huge performance benefits, but as you may know, it will help is reducing the disk footprint.
