Re: reduce null bitmap size - Mailing list pgsql-hackers

From Tom Lane
Subject Re: reduce null bitmap size
Date
Msg-id 15115.1320856755@sss.pgh.pa.us
Whole thread Raw
In response to reduce null bitmap size  (yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi))
Responses Re: reduce null bitmap size  (yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi))
List pgsql-hackers
yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi) writes:
> how about making heap_form_tuple and its variants use smaller natts for
> tuples whose trailing columns are NULL?

This idea has been proposed before, and rejected on the basis that it's
unlikely to save enough to be worth the cycles needed to check for the
case.  Keep in mind that you aren't going to save anything at all unless
the bitmap length decreases across a MAXALIGN boundary.
        regards, tom lane


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