Proposal for Null Bitmap Optimization(for Trailing NULLs)

Hi,<br />    Currently we check for the existence of NULL values in the tuple and we set the has_null flag. If the
has_nullflag is present, the tuple will be storing a null bitmap. What i propose is<br /><br />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
aretrailing nulls, then we will not set the has_null flag and we will not have the null bitmap with the tuple. <br
/><br/>b) While selecting the tuple, we will check whether the tuple offset equals / exceeds the length of the tuple
andthen mark the remaining attributes of the tuple as null. To be exact, we need to modify the slot_deform_tuple in
orderto achieve the same. <br /><br />This may not give huge performance benefits, but as you may know, it will help is
reducingthe disk footprint.<br /><br /><br />Expecting your comments..<br clear="all" /><br />-- <br />Thanks,<br
/>Gokul.<br/>CertoSQL Project,<br /> Allied Solution Group.<br />(<a
href="http://www.alliedgroups.com">www.alliedgroups.com</a>)