Comments on: Hotsos 2009

By: Usage Stats « Oracle Scratchpad

Usage Stats « Oracle Scratchpad — Thu, 24 Jan 2013 19:00:58 +0000

[...] instability – especially since Oracle will take automatic sample sizes. With 11g and the “approximate NDV” the instability and workload is likely to be reduced – provided you’re not collecting [...]

By: I Wish « Oracle Scratchpad

I Wish « Oracle Scratchpad — Mon, 19 Dec 2011 11:56:14 +0000

[...] ? In view of the room for error, it might be sensible to implement the counts only as part of the approximate NDV mechanism that only runs if you choose the auto sample size option, and always seems to do a full [...]

By: Doug's Oracle Blog

Doug's Oracle Blog — Thu, 15 Dec 2011 03:18:38 +0000

Thanks Jonathan ……

… and Amit, of course!I mentioned during my SPM presentation that Amit Poddar’s excellent paper and presentation on One-Pass Distinct Sampling and Incremental Statistics had gone missing from the web, but Jonathan is now hosting the files on his ori…

By: Approximate NDV « Oracle Scratchpad

Approximate NDV « Oracle Scratchpad — Wed, 14 Dec 2011 14:28:15 +0000

[...] on the 11g Approximate NDV. There are links to a white paper and the presentation slides on my posting about Hotsos 2009 where I saw him give the [...]

By: Jonathan Lewis

Jonathan Lewis — Wed, 14 Dec 2011 14:22:22 +0000

Amit,

Thank you very much.
I’ve posted the files as pdfs to my blog and put links to them in the article.

By: poddar007Amit Poddar

poddar007Amit Poddar — Wed, 14 Dec 2011 14:07:23 +0000

Jonathan,

You can publish the paper on this site if you so desire. I am fine by it. I cannot maintain my own site due to personal reasons. This would be the best public place for the paper to be published in the alternative.

amit

By: VS

VS — Mon, 04 Jul 2011 13:46:15 +0000

Hi All,

Is the paper by Amit Poddar available at any other site, the original site http://www.oraclegeek.net is having some issues

Regards,
VS

By: Frequency Histogram 4 « Oracle Scratchpad

Frequency Histogram 4 « Oracle Scratchpad — Fri, 31 Dec 2010 15:38:49 +0000

[...] to note that space utilisation isn’t considered a threat in 11g when looking at the ‘synopsis’ approach of creating the ‘approximate NDV’ for columns. The difference may be due to the passage of time, of course, on the other hand the [...]

By: I wish (2) « Oracle Scratchpad

I wish (2) « Oracle Scratchpad — Fri, 18 Jun 2010 06:14:52 +0000

[...] – and you might argue that it’s better to make it a deliberate choice. Given the new ‘approximate NDV’ feature in 11.2 it might not be an expensive option to [...]

By: Val

Val — Thu, 23 Apr 2009 03:22:36 +0000

“Oracle has chosen 64 bits as their hash values so that they can address 2^64 distinct hash values (theoritically) without collisions.”

32 bit is not too bad. With perfect hash and million rows, the expected number of collision is about a hundred. Of course, with 64 bits, the theoretical number is negligible.