Date: Tue, 9 Mar 2021 18:48:43 -0500
From: Bruce Momjian <bruce@momjian.us>
To: "Bossart, Nathan" <bossartn@amazon.com>
Cc: Andres Freund <andres@anarazel.de>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
	"McAlister, Grant" <grant@amazon.com>,
	"Mlodgenski, Jim" <mlodj@amazon.com>,
	"Nasby, Jim" <nasbyj@amazon.com>, "Hsu, John" <hsuchen@amazon.com>
Subject: Re: partial heap only tuples
Message-ID: <20210309234843.GA16791@momjian.us>
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On Tue, Mar  9, 2021 at 09:33:31PM +0000, Bossart, Nathan wrote:
> I'm cautiously optimistic that index creation and deletion will not
> require too much extra work.  For example, if a new index needs to
> point to a partial heap only tuple, it can do so (unlike HOT, which
> would require that the new index point to the root of the chain).  The
> modified-columns bitmaps could include the entire set of modified
> columns (not just the indexed ones), so no additional changes would
> need to be made there.  Furthermore, I'm anticipating that the
> modified-columns bitmaps will end up only being used with the
> redirected LPs to help reduce heap bloat after single-page vacuuming.
> In that case, new indexes would probably avoid the existing bitmaps
> anyway.

Yes, that would probably work, sure.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee