Comments on: dbms_stats surprise

By: Log Buffer #83: a Carnival of the Vanities for DBAs

Log Buffer #83: a Carnival of the Vanities for DBAs — Fri, 08 Feb 2008 21:36:05 +0000

[...] Lewis, on his Oracle Scratchpad, has a dbms_stats surprise. “It’s been several years since I started telling people that one of the solutions to [...]

By: Jonathan Lewis

Jonathan Lewis — Tue, 05 Feb 2008 18:50:51 +0000

Yas,

That looks a reasonable observation based on the description given. However, in this case, I was interested only in the point that there is a Metalink note that adds a degree of “legality” to the use of the ‘set_xxxxxx_stats’ calls.

By: Yas

Yas — Tue, 05 Feb 2008 08:58:03 +0000

When the index with poor selectivity has a non-
uniform data distribution, the cost of the FTS may be lower than the
cost for the index range scan, still the performance using the index for
values with small number of rows may be better.

Jonathan, the note states the above. In such a case would not a histogram on that column help instead of setting the stats manually?

By: Virag Sharma

Virag Sharma — Tue, 05 Feb 2008 03:05:06 +0000

Thanks for pointer to valuable information.

By: Nigel Thomas

Nigel Thomas — Mon, 04 Feb 2008 21:47:47 +0000

Security by obscurity; I always thought Metalink was designed to squirrel away useful information by making it as hard to find as possible…

Regards Nigel