Re: Explain plan execution

premmehrotra_at_hotmail.com wrote:
> Execution Plan
> ----------------------------------------------------------
> 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=4 Card=2 Bytes=384)
> 1 0 SORT (ORDER BY) (Cost=4 Card=2 Bytes=384)
> 2 1 NESTED LOOPS (Cost=3 Card=2 Bytes=384)
> 3 2 TABLE ACCESS (BY INDEX ROWID) OF 'DM_SYSOBJECT_S' (Cos
> t=2 Card=2 Bytes=212)
>
> 4 3 INDEX (RANGE SCAN) OF 'D_1F00C73D8000000F' (NON-UNIQ
> UE) (Cost=3 Card=10)
>
> 5 2 TABLE ACCESS (BY INDEX ROWID) OF 'OS_DOCUMENT_S' (Cost
> =2 Card=1 Bytes=86)
>
> 6 5 INDEX (UNIQUE SCAN) OF 'D_1F00C73D80000D01' (UNIQUE)
>
>
> I will like to know what numbers in second "column" mean, I see there
> are two 2's - one 3 and one 5. Does that mean step 5 (based on second
> column) is done first, then srep3. What about two 2 steps. Which one is
> done first?
>
> Is DMS_SYSOBJECT_S really the driving table for nested loop join. I
> will be really surprised) because this table has lot more rows that
> OS_DOCUMNET_S table. I would think OS_DOCUMENT_S should be driving
> table.
>
>
>
> Thanks a lot,

The second column is cardinality aka the number of rows. Received on Fri Apr 14 2006 - 12:50:59 CDT