Re: Full table scan and select count(*)

Rick Denoire <100.17706_at_germanynet.de> wrote:
> I was trying to find the best value of db_file_multiblock_read_count
> in order to improve full table scans.
>
> So to test the effect of this setting, I started issuing the command
> select count(*) from tabq;
> tabq hast several Million rows.
>
> I got different results that surprise me a lot:
> PARAMETER Command Time
> 64 as above 12 sec
> 64 /*+ FULL(TABQ)*/ 57 sec

Oracle can count the number or rows using an index, as long as at least one of the columns in the index is not null.

Xho

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