Re: SQL statement -- about index and group by

[Quoted] Jurij Modic ¼¶¼g©ó¤å³¹ <353b6bff.31103304_at_www.sigov.si>...
>On 20 Apr 1998 11:42:47 GMT, "Chris Hamilton" <toneczar_at_erols.com>
>wrote:
>
>>°½Ãi¿ß <Grafield_at_grafield.com.tw> wrote ...
>>> When I issue an Select statement with group by ,
>>> is it useful to create a index on the columns in group by function ?
>>> example :
>>>
>>> There is a lot of data in Table Table_AA, I use
>>>
>>> SELECT COUNT(*), C_1, C_2, C_3, C_4, C_5
>>> FROM TABLE_AA
>>> GROUP BY C_1, C_2, C_3, C_4, C_5
>>>
>>> For the performance, do I need to create a index on (C_1, C_2, C_3,
 C_4,C_5 )
>>
>>I don't think an index would be beneficial for THIS statement. Since
>>you're not restricting the range of values returned, a full table scan is
>>needed, which would not use the indexes.
>
>Not quite true. If cost base optimizer is used, then indexes can be
>used even when there is no WHERE clause.

DOES ORACLE 7.3.2 SUPPORT COST BASE OR RULE BASE ? Received on Tue Apr 21 1998 - 00:00:00 CEST