Simple query takes 18 minutes to retrieve data....

Question

Hi,
I am facing this problem at the customer site where a simple query on a table takes 18 minutes or more. Please find below the details.
Table Structure
CREATE TABLE dsp_data
quantum_id NUMBER(11) NOT NULL,
src      NUMBER(11) NOT NULL,
call_status NUMBER(11) NOT NULL,
dst NUMBER(11) NOT NULL,
measurement_id NUMBER(11) NOT NULL,
is_originating NUMBER(1)     NOT NULL,
measurement_value NUMBER(15,4) NOT NULL,
data_type_id NUMBER(3) NOT NULL,
data VARCHAR2(200) NOT NULL
TABLESPACE dsp_data_tspace
STORAGE (PCTINCREASE 0 INITIAL 100K NEXT 1024K)
PARTITION BY RANGE (quantum_id)
(PARTITION dsp_data_default VALUES LESS THAN (100));
CREATE INDEX dsp_data_idx ON dsp_data
quantum_id,
src,
     call_status,
dst,
     measurement_id,
     is_originating,
measurement_value,
data_type_id
TABLESPACE dsp_data_idx_tspace
LOCAL;
CREATE INDEX dsp_data_src_idx ON dsp_data
src
TABLESPACE dsp_data_idx_tspace
LOCAL;
CREATE INDEX dsp_data_dst_idx ON dsp_data
dst
TABLESPACE dsp_data_idx_tspace
LOCAL;
ALTER TABLE dsp_data
ADD CONSTRAINT fk_dsp_data_1
FOREIGN KEY
quantum_id
REFERENCES mds_measurement_intervals
quantum_id
ALTER TABLE dsp_data
ADD CONSTRAINT fk_dsp_data_2
FOREIGN KEY
data_type_id
REFERENCES mds_drilldown_types
type_id
ALTER TABLE dsp_data
ADD CONSTRAINT pk_dsp_data
PRIMARY KEY
quantum_id,
src,
call_status,
dst,
          measurement_id,
          is_originating,
measurement_value,
data_type_id,
data
USING INDEX
TABLESPACE dsp_data_idx_tspace
LOCAL;
Table Space Creation
All table space creation is done using following command
CREATE TABLESPACE [tablespaceName]
DATAFILE [tablespaceDatafile] SIZE 500M REUSE
AUTOEXTEND ON NEXT 10240K
DEFAULT STORAGE ( INITIAL 1024K
NEXT 1024K
MINEXTENTS 10
MAXEXTENTS UNLIMITED
PCTINCREASE 0
Server Configuration on CUtsomer Site
(1)     2 x Dual PA8900 Proc = 4GHz
(2)     RAM = 16GB
(3)     3 x Internal HDDs
(4)     1 x External MSA-30 storage array (oracle db)
Record Information On Customer Site
select count(*) from dsp_data;
COUNT(*)
181931197
select min (quantum_id) from dsp_data where dst=2;
This takes 18 minutes or more....
SQL> SQL> SQL> explain plan for select min (quantum_id) from dsp_data where dst=2;
Explained.
SQL> @?/rdbms/admin/utlxpls
PLAN_TABLE_OUTPUT
Plan hash value: 999040277
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 1 | 14 | 1 (0)| 00:00:01 | | |
| 1 | SORT AGGREGATE | | 1 | 14 | | | | |
| 2 | FIRST ROW | | 92 | 1288 | 1 (0)| 00:00:01 | | |
| 3 | PARTITION RANGE ALL | | 92 | 1288 | 1 (0)| 00:00:01 | 1 | 29 |
|* 4 | INDEX FULL SCAN (MIN/MAX)| DSP_DATA_IDX | 92 | 1288 | 1 (0)| 00:00:01 | 1 | 29 |
As mentioned above the query takes 18 minutes or more. This is a critical issue at customer. Can you please give your suggestions how to improve and reduce the query time. Thanks in advance.

Answer 1

Hi,
I did the following changes in the indexes of table.
drop index DSP_DATA_IDX;
create index DSP_DATA_MEASUREMENT_ID_IDX on DSP_DATA (MEASUREMENT_ID) TABLESPACE dsp_data_idx_tspace LOCAL;
After that I did explain plan,
explain plan for select min(QUANTUM_ID) from mds.DSP_DATA where SRC=11;
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost (%CPU
| 0 | SELECT STATEMENT | | 1 | 11 | 3 (0
| 1 | SORT AGGREGATE | | 1 | 11 |
| 2 | FIRST ROW | | 430K| 4626K| 3 (0
| 3 | PARTITION RANGE ALL | | 430K| 4626K| 3 (0
| 4 | INDEX FULL SCAN (MIN/MAX)| PK_DSP_DATA | 430K| 4626K| 3 (0
Note
- 'PLAN_TABLE' is old version
14 rows selected
SELECT table_name, index_name, monitoring, used FROM v$object_usage;
TABLE_NAME INDEX_NAME MONITORING USED
DSP_DATA DSP_DATA_SRC_IDX YES NO
It seems that DSP_DATA_SRC_IDX is not getting used in query. What changes do i need to make so that DSP_DATA_SRC_IDX index gets used.
Also, you have stated that to create global index on src and dst. How do i create them.
Thanks in Advance.
Edited by: 780707 on Jul 8, 2010 11:58 PM