Re: Covering Indexes

Aidan Van Dyk <aidan@highrise.ca>

From: Aidan Van Dyk <aidan@highrise.ca>

To: Alvaro Herrera <alvherre@commandprompt.com>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andrew Dunstan <andrew@dunslane.net>, Jeff Janes <jeff.janes@gmail.com>, "David E. Wheeler" <david@justatheory.com>, Pg Hackers <pgsql-hackers@postgresql.org>

Date: 2012-06-28T16:23:52Z

Lists: pgsql-hackers

On Thu, Jun 28, 2012 at 12:12 PM, Alvaro Herrera
<alvherre@commandprompt.com> wrote:

> The other question is whether such an index would prevent an update from
> being HOT when the non-indexed values are touched.  That could be a
> significant difference.

I don't see Index-Only-Scans being something that will be used in
"high churn" tables.

So as long as the value of these "covering/included" fields is tied to
index-only scans, maybe it isn't a problem?

Of course, we have have a hard time convincing people that the  "index
only" scans they want can't be "index only" because heap pages aren't
"all visible"...

a.

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