Re: Proposal for Null Bitmap Optimization(for TrailingNULLs) - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Proposal for Null Bitmap Optimization(for TrailingNULLs)
Date
Msg-id 5031.1198012525@sss.pgh.pa.us
Whole thread Raw
In response to Re: Proposal for Null Bitmap Optimization(for TrailingNULLs)  ("Gokulakannan Somasundaram" <gokul007@gmail.com>)
Responses Re: Proposal for Null Bitmap Optimization(for TrailingNULLs)  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-hackers
"Gokulakannan Somasundaram" <gokul007@gmail.com> writes:
>    I have currently completed the following
> a) If there are only trailing nulls in the heap, no null-bitmap gets stored
> b) If there are trailing nulls in addition to nulls inbetween values in the
> heap, then the trailing nulls are not added to the null-bitmap. I wouldn't
> have done it, but it came almost free of cost
> c) If there are only trailing nulls in the index, no null-bitmap gets stored

> The index part gave some issues and i hope i have fixed it.

I doubt you have fixed it; I doubt it's *possible* to fix it without
significant rejiggering of IndexTuple representation.  The problem is
that IndexTuple lacks a number-of-fields field, so there is no place
to indicate how many null bitmap bits you have actually stored.
I would suggest forgetting that part and submitting the part that
has some chance of getting accepted.
        regards, tom lane


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