Re: Oracle ignoring function-based index - why?

Sybrand,

Can you elaborate where oracle recommends a 20 percent value for estimate_statistics?
I've seen oracle recommend using auto sample size. However, nowhere have I seen a number like 20% recommended. Also, the default for histogram is 1.
http://download-west.oracle.com/docs/cd/B10501_01/appdev.920/a96612/d_stats2.htm#1003993

"FOR ALL COLUMNS SIZE 1" does not gather any histogram. Its not ridiculous as you claim it to be. If OP does not want to gather any histograms than this value if fine.

Also, your suggestion of a default 200 value for all indexed columns is ridiculous (I'm using your lingo now). Oracle suggests using "AUTO". Gathering histograms for
columns which are not skewed will only harm performance. Also, non-indexed columns
can benefit from histograms.

Also, degree of parallelization is not necessarily dependent on number of CPU's. This has been debated a number of times in this forum. Try googling this.

Anurag Received on Mon Jul 25 2005 - 11:34:48 CDT