Connect by taking too long

Question

Hello,
I have a table "a" that has:
left_id right_id type
4 5 1
4 6 1
4 7 1
5 9 2
5 10 2
5 11 2
9 13 3
13 14 4
10 15 3
QUERY:
select left_id, right_id, type from
a
connect by left_id = prior right_id
start with left_id = 4;
Execution Plan
Plan hash value: 2739023583
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 29 | 1131 | 18 (12)| 00:00:01 |
|* 1 | CONNECT BY WITH FILTERING| | | | | |
|* 2 | INDEX RANGE SCAN | a_PK | 5 | 65 | 3 (0)| 00:00:01 |
| 3 | NESTED LOOPS | | 24 | 624 | 13 (0)| 00:00:01 |
| 4 | CONNECT BY PUMP | | | | | |
|* 5 | INDEX RANGE SCAN | a_PK | 5 | 65 | 2 (0)| 00:00:01 |
Predicate Information (identified by operation id):
1 - access("LEFT_ID"=PRIOR "RIGHT_ID")
2 - access("LEFT_ID"=4)
5 - access("LEFT_ID"="connect$_by$_pump$_002"."prior right_id ")
Is there a way to optimize the query?
The query is taking too long.
-Thanks
Karthik
Edited by: user3934098 on Nov 14, 2010 1:50 AM

Answer 1

Here is the detailed explaination:
Version: oracle 10g R2
Create table statement:
CREATE TABLE A
"LEFT_ID" NUMBER(9,0) NOT NULL ENABLE,
"RIGHT_ID" NUMBER(9,0) NOT NULL ENABLE,
"TYPE" NUMBER(9,0) NOT NULL ENABLE,
CONSTRAINT "A_PK" PRIMARY KEY ("LEFT_ID", "RIGHT_ID", "TYPE") USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) TABLESPACE "DATA" ENABLE,
CONSTRAINT "A_FK1" FOREIGN KEY ("TYPE") REFERENCES "B" ("TYPE") ENABLE
SEGMENT CREATION IMMEDIATE PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING STORAGE
INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT
TABLESPACE "DATA" ;
Insert statements:
INSERT INTO A VALUES(4, 5, 1);
INSERT INTO A VALUES(4, 6, 1);
INSERT INTO A VALUES(4, 7, 1);
INSERT INTO A VALUES(5, 9, 2);
INSERT INTO A VALUES(5, 10, 2);
INSERT INTO A VALUES(5, 11, 2);
INSERT INTO A VALUES(9, 13, 3);
INSERT INTO A VALUES(13, 14, 4);
INSERT INTO A VALUES(10, 15, 3);
INDEXES:
CREATE UNIQUE INDEX "A_PK" ON "A" ("LEFT_ID", "RIGHT_ID", "TYPE") PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645 PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) TABLESPACE "DATA" ;
QUERY:
select left_id, right_id, type from
a
connect by left_id = prior right_id
start with left_id = 4;
THE table has 951053 rows
The explain plan is:"
Execution Plan
Plan hash value: 2739023583
Id Operation Name Rows Bytes Cost (%CPU) Time
0 SELECT STATEMENT 29 1131 18 (12) 00:00:01
* 1 CONNECT BY WITH FILTERING
* 2 INDEX RANGE SCAN a_PK 5 65 3 (0) 00:00:01
3 NESTED LOOPS 24 624 13 (0) 00:00:01
4 CONNECT BY PUMP
* 5 INDEX RANGE SCAN a_PK 5 65 2 (0) 00:00:01
Predicate Information (identified by operation id):
1 - access("LEFT_ID"=PRIOR "RIGHT_ID")
2 - access("LEFT_ID"=4)
5 - access("LEFT_ID"="connect$_by$_pump$_002"."prior right_id ")
Now is there a way to optimize the query? The query takes about a min to excute. This will be my inner query.
" Is there any other information that you may need? Am I missing something here? "
-Thanks
Karthik
Edited by: user3934098 on Nov 14, 2010 2:22 AM