Re: Bitmap index costing - how to influence

Chris,

if you can influence the query, then you can try to lower the cost of the 
bitmap index access specifically to that query by using the (undocumented) 
OPT_PARAM hint introduced in 10g:

select /*+ opt_param('optimizer_index_cost_adj', 10) */ ...

If you can't modify the query but the query is static, you could apply this 
hint using Stored Outlines or SQL profiles in 10g.

Regards,
Randolf

Oracle related stuff blog:
http://oracle-randolf.blogspot.com/

SQLTools++ for Oracle (Open source Oracle GUI for Windows):
http://www.sqltools-plusplus.org:7676/
http://sourceforge.net/projects/sqlt-pp/

> I am pretty much stuck on a bitmap costing problem.
>
> Any ideas on how to influence bitmap index cost, relative to full
> table scan cost? Anything goes as long as it doesn't break b-tree
> index costing.
>
> - optimizer_index_cost_adj - i will have to set this to 10 (10 times
> cheaper) for bitmaps to be used. I am concerned about proper
> calculations of b-tree indexes vs full table scans
>
> Any other ideas?


_______________________________________________________________________
DSL zum Nulltarif + 20 Euro Extraprämie bei Online-Bestellung über die
DSL Freundschaftswerbung! http://dsl.web.de/?ac=OM.AD.AD008K15279B7069a

--
http://www.freelists.org/webpage/oracle-l


Other related posts: