Re: estimating # of distinct values

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Tomas Vondra" <tv(at)fuzzy(dot)cz>,"Robert Haas" <robertmhaas(at)gmail(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: estimating # of distinct values
Date: 2010-12-27 22:49:51
Message-ID: 4D18C3AF0200002500038BEF@gw.wicourts.gov
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> With respect to (b), I think I'd need to see a much more detailed
> design for how you intend to make this work. Off the top of my
> head there seems to be some pretty serious feasibility problems.

I had one random thought on that -- it seemed like a large concern
was that there would need to be at least an occasional scan of the
entire table to rebuild the distinct value information. Don't we
already require an occasional scan of the entire table for freezing
transaction IDs? Could this be part of any vacuum of the entire
table?

-Kevin

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2010-12-27 22:55:12 Re: estimating # of distinct values
Previous Message Kevin Grittner 2010-12-27 22:36:42 Re: SSI memory mitigation & false positive degradation