Re: Proposal for Null Bitmap Optimization(for Trailing NULLs)

We can also implement the same for index tuples.....

On Dec 17, 2007 1:10 PM, Gokulakannan Somasundaram <gokul007(at)gmail(dot)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.
>
>
> Expecting your comments..
>
> --
> Thanks,
> Gokul.
> CertoSQL Project,
> Allied Solution Group.
> (www.alliedgroups.com)

--
Thanks,
Gokul.
CertoSQL Project,
Allied Solution Group.
(www.alliedgroups.com)