Re: CBO cost and avg_row_len

Thanks Sybrand,

But why DBMS_STATS.GATHER_TABLE_STATS generates 3 statistics : num_rows, blocks and avg_row_len ?

Dias

Sybrand Bakker <gooiditweg_at_sybrandb.demon.nl> wrote in message news:<4qkogvoob381bka3g96sdg768718rsbhpq_at_4ax.com>...
> On 9 Jul 2003 08:34:56 -0700, ydias_at_hotmail.com (dias) wrote:
>
> >Hi,
> >
> >Can someone explain when the CBO takes into account the value of
> >avg_row_len to estimate an access plan cost ?
> >
> >I suppose that the CBO uses this value to estimate the cost for a
> >table scan, in combination with the number of blocks and the value of
> >db_file_multiblock_read_count ?
> >
> >Thanks
>
> It doesn't. It would also be unnecessary, as a block is a block is a
> block and a table scan is a table scan is a table scan. Oracle will
> always read a complete block. The number of blocks in use is taken
> into account.
>
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address
Received on Thu Jul 10 2003 - 05:08:34 CDT