| From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
|---|---|
| To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Florian Pflug <fgp(at)phlo(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: ANALYZE sampling is too good |
| Date: | 2013-12-12 19:20:50 |
| Message-ID: | CAGTBQpaRYAedJS=zJHnitiJj8pCFzoDR-FipuAwEoGEw1Ez=vw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 12, 2013 at 4:13 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>> Well, why not take a supersample containing all visible tuples from N
>> selected blocks, and do bootstrapping over it, with subsamples of M
>> independent rows each?
>
>
> Bootstrapping methods generally do not work well when ties are significant
> events, i.e. when two values being identical is meaningfully different from
> them being very close but not identical.
Yes, that's why I meant to say (but I see now that I didn't) that it
wouldn't do much for n_distinct, just the histogram.
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