Re: reduce null bitmap size

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: yamt(at)mwd(dot)biglobe(dot)ne(dot)jp (YAMAMOTO Takashi)
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: reduce null bitmap size
Date: 2011-11-09 16:39:15
Message-ID: 15115.1320856755@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

yamt(at)mwd(dot)biglobe(dot)ne(dot)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

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Andrew Dunstan 2011-11-09 16:46:28 Re: parallel make failure
Previous Message Tom Lane 2011-11-09 16:35:57 Re: parallel make failure