SQL versions with cursor_sharing=similar

Question

Hello,
We have a Peoplesoft DB and we have been obliged to use cursor_sharing=similar to solve some of our problems. We have just noticed that with Oracle *9.2.0.7*, when a table is partitioned, many versions of the same sql are created in the SGA. Here is the demo
CREATE TABLE T5
  ID    NUMBER(2),      
  NAME  VARCHAR2(15 BYTE)
PARTITION BY RANGE (ID) 
  PARTITION P1 VALUES LESS THAN (10),
  PARTITION P2 VALUES LESS THAN (20),
  PARTITION P3 VALUES LESS THAN (30),
  PARTITION P_MAXVALUE VALUES LESS THAN (MAXVALUE));
alter session set cursor_sharing=similar;
select count(*) from t5 where id = 1;
select count(*) from t5 where id = 10;
select count(*) from t5 where id = 30;
select count(*) from t5 where id = 5;  
select count(*) from t5 where id = 15;Now we check the SGA:
SQL> select hash_value,CHILD_NUMBER,EXECUTIONS,sql_text from v$sql where SQL_TEXT like '%t5%';
HASH_VALUE CHILD_NUMBER EXECUTIONS SQL_TEXT
602987019            0          1 select count(*) from t5 where id = :"SYS_B_0"
602987019            1          1 select count(*) from t5 where id = :"SYS_B_0"
602987019            2          1 select count(*) from t5 where id = :"SYS_B_0"
602987019            3          1 select count(*) from t5 where id = :"SYS_B_0"
602987019            4          1 select count(*) from t5 where id = :"SYS_B_0"Is there a way to avoid all these child cursors?
Has anyone had this same problem before?

Answer 1

Well, I just tried it, but this time with a table NOT partitioned, no histograms and no range operation, with Oracle version 10.2.0.1 and I got the same results:
SQL> CREATE TABLE T6
  ID    NUMBER(2),
  NAME  VARCHAR2(15 BYTE)
SQL> alter session set cursor_sharing=similar;
Session altered.
SQL>
SQL> select count(*) from t6 where id = 1;
  COUNT(*)
         0
SQL> select count(*) from t6 where id = 10;
  COUNT(*)
         0
SQL> select count(*) from t6 where id = 30;
  COUNT(*)
         0
SQL> select count(*) from t6 where id = 5;
  COUNT(*)
         0
SQL> select count(*) from t6 where id = 15;
  COUNT(*)
         0
SQL> select hash_value,CHILD_NUMBER,EXECUTIONS,sql_text
from v$sql where SQL_TEXT like '%t6%';
HASH_VALUE CHILD_NUMBER EXECUTIONS SQL_TEXT
2780697141            0          1 select count(*) from t6 where
                                   id = :"SYS_B_0"
2780697141            1          1 select count(*) from t6 where
                                   id = :"SYS_B_0"
2780697141            2          1 select count(*) from t6 where
                                   id = :"SYS_B_0"
2780697141            3          1 select count(*) from t6 where
                                   id = :"SYS_B_0"
HASH_VALUE CHILD_NUMBER EXECUTIONS SQL_TEXT
2780697141            4          1 select count(*) from t6 where
                                   id = :"SYS_B_0"
2776262046            0          2 select hash_value,CHILD_NUMBER
                                   ,EXECUTIONS,sql_text from v$sq
                                   l where SQL_TEXT like '%t6%'
6 rows selected.So?