Re: Explain plan execution

hpuxrac wrote:
> 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.

You are obviously not reading the original post, as what you consider the second column is not the column in the OP's reference. Read the text again and you'll realise Steve provided the correct response as the OP refers to the second column of numbers in the explain plan output:

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)

   ^   Column "1"
         ^ Column "2"

which has nothing to do with cardinality and everything to do with referencing the ID of the parent operation.

Your answer, with respect to the original question. is incorrectly worded and appears to describe Column "2" as I have it marked, and as the OP intended the output to be read.

David Fitzjarrell Received on Sat Apr 15 2006 - 08:16:13 CDT