Hi Nuno (and list),
Changing 'optimizer_index_caching' and 'optimizer_index_cost_adj' does seem to
inhibit cursor sharing under 8i. You may want to try the following test under
8.0 and see if it is any different.
SQL> create table t as select * from dual;
Table created.
SQL> analyze table t compute statistics;
Table analyzed.
SQL> select count(*) from t;
COUNT(*)
----------
1
SQL> select parse_calls, version_count from v$sqlarea where sql_text = 'select
count(*) from t ';
PARSE_CALLS VERSION_COUNT
----------- -------------
1 1
SQL> show parameters optimizer_index
NAME TYPE VALUE
------------------------------------ ------- ------------------------------
optimizer_index_caching integer 0
optimizer_index_cost_adj integer 100
SQL> alter session set optimizer_index_caching = 1;
Session altered.
SQL> select count(*) from t;
COUNT(*)
----------
1
SQL> select parse_calls, version_count from v$sqlarea where sql_text = 'select
count(*) from t ';
PARSE_CALLS VERSION_COUNT
----------- -------------
2 2
SQL> alter session set optimizer_index_cost_adj = 99;
Session altered.
SQL> select count(*) from t;
COUNT(*)
----------
1
SQL> select parse_calls, version_count from v$sqlarea where sql_text = 'select
count(*) from t ';
PARSE_CALLS VERSION_COUNT
----------- -------------
3 3
SQL>
@ Regards,
@ Steve Adams
@ http://www.ixora.com.au/
@ http://www.christianity.net.au/
-----Original Message-----
Sent: Thursday, 10 May 2001 0:51
To: Multiple recipients of list ORACLE-L
[snip]
Now, start
playing with OPTIMIZER_INDEX_CACHING and OPTIMIZER_INDEX_COST_ADJ.
Incidentally, these can be set at session level but to get them picked
up you need to do a FLUSH SHARED_POOL. Which kinda defeats the
purpose of making them dynamic in the first place, Mr. ORACLE? Or am
I missing something obvious? I can imagine someone doing this at the
beginning of each batch job and flushing the shared pool each time!
Jeez, some database coders don't have a clue about the real world, do
they?...
[snip]
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Steve Adams
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