How improve performance on access path TABLE ACCESS BY INDEX ROWID ?

Question

I have table MOVEMENT with about 26millions entries,
select rowid from movement xxx
where
xxx.sTransType > 0
AND xxx.sDevice < 1000
AND xxx.sDevice >= 0
AND (bitand(xxx.sSaleFlag,1) = 0 AND bitand(xxx.sSaleFlag,4) = 0)
AND xxx.sArtClassRef < 100
and xxx.tActionTime BETWEEN TO_DATE('13-05-2011 08:08:34', 'dd-mm-yyyy hh24:mi:ss') AND to_date('13-05-2011 14:08:34', 'dd-mm-yyyy hh24:mi:ss') ;
PLAN_TABLE_OUTPUT
Plan hash value: 679628763
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 34 | 10102 (1)| 00:02:02 |
|* 1 | TABLE ACCESS BY INDEX ROWID| MOVEMENT | 1 | 34 | 10102 (1)| 00:02:02 |
|* 2 | INDEX RANGE SCAN | MOVATIME_IX | 18489 | | 51 (0)| 00:00:01 |
Predicate Information (identified by operation id):
1 - filter("XXX"."SARTCLASSREF"<100 AND BITAND("XXX"."SSALEFLAG",1)=0 AND
BITAND("XXX"."SSALEFLAG",4)=0 AND "XXX"."STRANSTYPE">0 AND "XXX"."SDEVICE"<1000
AND "XXX"."SDEVICE">=0)
2 - access("XXX"."TACTIONTIME">=TO_DATE('2011-05-13 08:08:34', 'yyyy-mm-dd
hh24:mi:ss') AND "XXX"."TACTIONTIME"<=TO_DATE('2011-05-13 14:08:34', 'yyyy-mm-dd
hh24:mi:ss'))
there is index on tActionTime - MOVATIME_IX
This query returns 12203 rows, so I would anticipate this number in plan table in row with id 1 and column Rows
Final question if it is possible to optimize this query and what are the next steps to do it?
Thanks.

Answer 1

>
I thought that access path via ROWID's is the fastest way to get row
>
It is the fastest way to get the row - FROM THE TABLE.
But the ROWIDs have to be gotten from the index. That is what the INDEX RANGE SCAN is doing. It is getting the ROWIDs needed and then the TABLE ACCESS BY INDEX ROWID is getting the rows.
>
I'am still confused with COST values, TABLE ACCESS BY INDEX ROWID has 200times higher cost than INDEX RANGE SCAN,
>
The index entries for a range scan are in order so they are very compact. The actual rows might be all over the place.
Have you ever you a library? Not the online ones - I mean the old-fashioned kind that actually has books printed on paper?
If the librarian asks you, her helper, to go get all books whose title begins with the letter 'B' how would you do it?
You could go back to the stacks and look at every book on every shelf for books with titles' starting with 'B'. That is the same as a FULL TABLE SCAN.
Or you could go to the card catalog, pull out the drawer (or drawers) that has 'B' on the label and look at the information on the card. Part of that information is the location of the actual book: section, stack; that is similar to the ROWID.
The card catalog might get you to the right stack of books; then you have to search the stack sequentially to look for the book by name.
A ROWID will get Oracle to the right block but then it has to find the right row.
So the cost of getting ROWIDs from an index using a RANGE SCAN (where values are scanned in order) is a lot cheaper than actually getting the rows. The first two index entries needed might be right next to each other in order but the rows themselves might be far apart on the disk.