?
Solved

SELECT MAX(TO_NUMBER(COL1)) FROM TABLE1 WHERE COL2=&VAL2;

Posted on 2001-07-05
9
Medium Priority
?
3,152 Views
Last Modified: 2010-08-05
How to optimize the select statement?

COL1 is of char(15).
TABLE1 is hash-partitioned on COL2.
Hash-partitioned non-unique index on COL2.

Oracle version 8.1.7.1
0
Comment
Question by:ooiewe
9 Comments
 
LVL 9

Expert Comment

by:dbalaski
ID: 6258351
Need a little more info -- please post the actual select statement...
Also --  do you have a current explain plan on the query

dB
0
 
LVL 9

Expert Comment

by:dbalaski
ID: 6258359
never mind the query --  I just noticed it was the title of the message

still the current explain plan would be helpful --
what is the apx size of the table ?  # of partitions?    apx distribution on col2??

dB
0
 

Author Comment

by:ooiewe
ID: 6258438
SELECT STATEMENT, COST=1, CARDINALITY=1
SORT AGGREGATE, COST=1, CARDINALITY=1
TABLE ACCESS BY LOCAL INDEX ROWID TABLE1, COST=1,CARDINALITY = 2605
INDEX RANGE SCAN IDX_COL2_ON_TABLE1, COST=1, CARDINALITY=2605

15 millions records
# of partitions = 4
0.1% (1 in 1000 records)

Additional info :
AVG_ROW_LEN=103
0
VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

 

Expert Comment

by:shikhadh
ID: 6258568
probably something wrong inthe memory.memory optimisation needs to be done.i would suggest u to use tkprof instaed of explan plan and then see what is wrong where
0
 

Expert Comment

by:wlang
ID: 6260196
If you can change col1 to number instead of char, it helps. Or you can create function index on col1 (oracle 8i)
0
 
LVL 9

Accepted Solution

by:
dbalaski earned 800 total points
ID: 6260291
That is not too bad --  the only thing I can think of is to avoid the sort ...

One way you can do this:
build a composite index on   (COL1,COL2)
this would produce an index range scan
maybe you could then apply an INDEX_FFS
hint..

The only thing I can think of at the moment...

dB
0
 
LVL 9

Expert Comment

by:dbalaski
ID: 6260383
This went in as a proposed answer -- it was supposed to be a comment...  must be a glitch,  I know comment was checked off.

dB
0
 

Author Comment

by:ooiewe
ID: 6261420
Function index is possible in general to speed up similar query, but it will slow down DML.

Give me some time to try out the proposed indexing.
0
 

Author Comment

by:ooiewe
ID: 6411896
You have answered my question correctly. For your info, Oracle is using INDEX_FFS even though it is not specified as a hint. Thanks alot.
0

Featured Post

Free learning courses: Active Directory Deep Dive

Get a firm grasp on your IT environment when you learn Active Directory best practices with Veeam! Watch all, or choose any amount, of this three-part webinar series to improve your skills. From the basics to virtualization and backup, we got you covered.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Working with Network Access Control Lists in Oracle 11g (part 1) Part 2: http://www.e-e.com/A_9074.html So, you upgraded to a shiny new 11g database and all of a sudden every program that used UTL_MAIL, UTL_SMTP, UTL_TCP, UTL_HTTP or any oth…
Checking the Alert Log in AWS RDS Oracle can be a pain through their user interface.  I made a script to download the Alert Log, look for errors, and email me the trace files.  In this article I'll describe what I did and share my script.
This video shows how to Export data from an Oracle database using the Original Export Utility.  The corresponding Import utility, which works the same way is referenced, but not demonstrated.
This video explains what a user managed backup is and shows how to take one, providing a couple of simple example scripts.
Suggested Courses

840 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question