Re: Periodic Stats Collection -- CBO Stats Myth? -- delta refresh of statistics
- From: "jaromir nemec" <jaromir@xxxxxxxxxxxx>
- To: <tim@xxxxxxxxx>, <breitliw@xxxxxxxxxxxxx>
- Date: Mon, 6 Oct 2008 21:15:05 +0200
Hello Tim, Wolfgang,
> Just how inaccurate is part of the game-theory that we all use when deciding
> between COMPUTE STATISTICS and ESTIMATE STATISTICS.
I'm wondering why Oracle doesn't support the third option: delta refresh of the
statistics. With the strong support of materialized view and fast refresh, I
can imagine this will be a very similar concept. Currently if I use the terms
of MV only full refresh of statistics is possible (or a full refresh based on
sample).
> .and determine the min and max values for columns based on the values in the
> rows returned by the sample.
The min and max will be solved natively. Possible, some obstacles will arise by
distinct values and histograms. But if I understand it correctly, there already
exist some algorithm solving this for maintaining the global statistics of a
partition table after gathering of the statistics of a single partition. (I'm
not sure if this algorithm is published).
Of course there will be data categories where the delta refresh would not work
very precise, but I guess for majority of business data it could yield good
results.
Any comments?
Regards,
Jaromir D.B. Nemec
Other related posts:
