Result Cache hint in Oracle 11 g

I have a problem with the RESULT_CACHE hint , this has been used in the various function in our database e.g
Function xyz (input IN table1.col1%type)
RETURN BOLEAN
RESULT_CACHE
AS
DATE_VALUE DATE;
BEGIN
SELECT x INTO DATE_VALE FROM TABLE2 WHERE COLUMN3=INPUT;
IF DATE_VALUE <SYSDATE
RETURN TRUE;
ELSE
RETURN FALSE;
END IF;
EXCEPTION WHEN NO_DATA_FOUND
THEN
RETURN FALSE;
END;
Now the value of DATE_VALUE is fetched in stored in cache, based on the input . but the value of DATE_value is changed after some db operations .
Oracle will return the same value even after the value has been changed for the same input (assume that the true/false is changed after the date_value is changed. )
So clearly in this function RESULT_CACHE has not been used correctly.
what could be the solution for this , Result_cache has been used in 20+ function and code change is not possible at this time.
can we use DBMS_RESULT_CACHE.BYPASS(TRUE) ;
is it at instance level , or session level. we will be running oracle job using the procedure which uses this function ,so before each job do we need to run this pkg.(DBMS_RESULT_CACHE.BYPASS(TRUE)) ?
we do not want to use FLUSH as we will have to do it every time before the job runs .
or any other solution .
DATABASE Details are :
Oracle 11g Enterprise edition 11.1.0.7.0- 64 bit
HPUX version 11.1.0.7.0

Su**** wrote:
Yes Tubby you are correct,
removing the result_cache from function is the permanent solution here,
But I want to know if anyone have encountered the same problem and use the BYPASS ,FLUSH etc to get a temporary solution . Thanks much.Your application has a bug. It has a bug because your developers didn't have time, or didn't care to read the documentation and understand what they were doing.
Why would you not want to fix that bug, choosing a workaround that may or may not work, and may or may not have undesired side effects on other portions of your application when the obvious solution is to remove the RESULT_CACHE from the function declaration where it was erroneously placed to begin with?
Worst case scenario, you remove that and the application works slower ... but correctly. I don't see how that's problematic.
Cheers,

Similar Messages

Result Cache in oracle 11g release 2.0.2.0

All,
Few months back I was trying Result Cache feature of 11g release 2.0.1.0. That time oracle mentioned that they have 3 modes to use this feature by setting result_cache_mode paramter to AUTO, FORCE or MANUAL. With AUTO mode (result_cache_mode=AUTO) you can identify queries that may benefit from result cache. I would like to know whcih views or function I should see where it captures this information.
In 11.2.0.1.0 documentation it was referencing some views (I totally don't remember those views names) and said those will be available in 11.2.0.2.0.
Is anyone know about this?
Thanks in advance.

user2486753 wrote:
Though oracle doc doesn't say about AUTO it is still accepts that value and caches the result of the SQL query if you add /*+ result cache */ hint to the SQL.
I know that they did mentioned in 112010 some where that it will help users to find which SQL's are good candidates for caching by running the application for a while. I just couldn't fine it.If we are adding AUTO and still passing the hint, its the same behavior as like MANUAL. I am not sure that I have seen the value anywhere and neither its there in the docs too.
HTH
Aman....

Function result Cache in oracle 11G

Hi,
i am reading the following article and trying to reproduce same set of statements to learn about function result cache.
http://www.oracle.com/technology/oramag/oracle/07-sep/o57asktom.html
Details about my output:
SQL> create or replace
function not_cached
( p_owner in varchar2 )
return number
as
l_cnt number;
begin
select count(*)
into l_cnt
from t
where owner = p_owner;
sys.dbms_lock.sleep(1);
return l_cnt;
end;
Function created.
Elapsed: 00:00:00.13
SQL> create or replace
function cached
( p_owner in varchar2 )
return number
result_cache
relies_on(T)
as
l_cnt number;
begin
select count(*)
into l_cnt
from t
where owner = p_owner;
dbms_lock.sleep(1);
return l_cnt;
end;
Function created.
Elapsed: 00:00:00.08
SQL> exec dbms_output.put_line( not_cached( 'SCOTT' ) );
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.06
SQL> exec dbms_output.put_line( not_cached( 'SCOTT' ) );
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.01
SQL> SQL> exec dbms_output.put_line( not_cached( 'SCOTT' ) );
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL> SQL> set serveroutput on
SQL> exec dbms_output.put_line( not_cached( 'SCOTT' ) );
0
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL> SQL> exec dbms_output.put_line( cached( 'SCOTT' ) );
0
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL> SQL> exec dbms_output.put_line( cached( 'SCOTT' ) );
0
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL> SQL> exec dbms_output.put_line( cached( 'SCOTT' ) );
0
PL/SQL procedure successfully completed.
SQL> exec dbms_output.put_line( cached( 'SCOTT' ) );
0
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.01
I am supposed to get the results quickly for "cached" call. However, i still dont see any change in the response time. May i know what i am missing here?
Thank you
Giridhar

Try to play with
RESULT_CACHE_MAX_SIZE
http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/initparams206.htm#REFRN10272
RESULT_CACHE_MAX_RESULT
http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/initparams205.htm#REFRN10298

Enabling result cache

Hi,
I am trying to enable result cache feature at Oracle 11g R2 server. I am following the below steps but everytime the cache status is coming DISABLED. Please help me to correct it
1. I am setting the RESULT_CACHE_MAX_SIZE and RESULT_CACHE_MODE as below. Memory_Target is 1232M, so I chose to allocate 200M for result cache.
ALTER SYSTEM SET RESULT_CACHE_MODE=FORCE
System altered.
ALTER SYSTEM SET RESULT_CACHE_MAX_SIZE=200M
System altered.2. I am restarting the database
SHUTDOWN IMMEDIATE
STARTUP
3. I am querying the result cache status
SELECT DBMS_RESULT_CACHE.STATUS FROM DUAL
STATUS
DISABLEDI have configured other database servers for cache and its working fine. But i am not able to sort out what is going wrong in above scripts. Please help me if i am missing out some step.
Thanks

select * from v$version;you need "Enterprise Edition" http://docs.oracle.com/cd/B28359_01/license.111/b28287/editions.htm
for EE check this:
http://psoug.org/reference/dbms_result_cache.html
http://www.oracle.com/technetwork/articles/datawarehouse/vallath-resultcache-rac-284280.html
http://www.oracle-developer.net/display.php?id=503

Result cache doubt

what is the difference if i write relies_on clause or if i dont write it, technically please explain what exactly is the difference ??
create or replace function tax (i in varchar2)
return number
result_cache
is
begin
return i*0.08 ;
end;
create or replace function tax (i in varchar2)
return number
result_cache relies_on (emp)
is
begin
return i*0.08 ;
end;

http://docs.oracle.com/cd/B28359_01/appdev.111/b28370/function.htm#i34368
RELIES_ON
Specifies the data sources on which the results of a function depend. For more information, see Using the PL/SQL Function Result Cache. http://docs.oracle.com/cd/B28359_01/appdev.111/b28370/subprograms.htm#BABFHACJ
To enable result-caching for a function, use the RESULT_CACHE clause. When a result-cached function is invoked, the system checks the cache. If the cache contains the result from a previous call to the function with the same parameter values, the system returns the cached result to the invoker and does not reexecute the function body. If the cache does not contain the result, the system executes the function body and adds the result (for these parameter values) to the cache before returning control to the invoker.Not sure why are you talking about invalidated data, result_cache just invoked result from a previous call to the function if it exists, if not it executes the function body.
The clause relies_on just specifies the data sources on which the results of a function depend.
am i missing something??

Result Caching

I was going through the Result caching feature of Oracle 11g. Just eager to know
What are the differences between this and the DETERMINISTIC option.
If RESULT CACHE...RELIES ON(table/view) is an enhanced feature of the DETERMINISTIC option then what are the limitations of the DETERMINISTIC functions.
Thanks in advance

The DETERMINISTIC option does not really do anything
except satisfy certain syntax requriements. Then, shouldn't here be any difference?
SQL> set feed 3
SQL> set echo on
SQL> select * from v$version where rownum<=1;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Prod
SQL> create or replace package p is
2 counter number:=0;
3 end;
4 /
Package created.
SQL> create or replace function determ(p_in varchar2) return number deterministic is
2 begin
3 p.counter := p.counter + 1;
4 if p.counter<=10 then
5 return 0;
6 else
7 return p.counter;
8 end if;
9 end;
10 /
Function created.
SQL>
SQL> create or replace function non_determ(p_in varchar2) return number is
2 begin
3 p.counter := p.counter + 1;
4 if p.counter<=10 then
5 return 0;
6 else
7 return p.counter;
8 end if;
9 end;
10 /
Function created.
SQL>
SQL> create table emp_copy
2 as
3 select emp.*
4 from emp,(select rownum from dual connect by level <=10)
5 ;
Table created.
SQL>
SQL> exec p.counter:=0;
PL/SQL procedure successfully completed.
SQL>
SQL> select ename,determ(ename)
2 from emp_copy
3 where determ(ename)=0;
ENAME      DETERM(ENAME)
SMITH                  0
ALLEN                  0
WARD                   0
JONES                  0
MARTIN                 0
ALLEN                  0
WARD                   0
JONES                  0
MARTIN                 0
ALLEN                  0
WARD                   0
JONES                  0
MARTIN                 0
ALLEN                  0
WARD                   0
JONES                  0
16 rows selected.
SQL>
SQL> exec p.counter:=0;
PL/SQL procedure successfully completed.
SQL>
SQL> select ename,non_determ(ename)
2 from emp_copy
3 where non_determ(ename)=0;
ENAME      NON_DETERM(ENAME)
SMITH                      0
ALLEN                      0
WARD                       0
JONES                      0
MARTIN                     0
5 rows selected.Best regards
Maxim

Query result caching on oracle 9 and 10 vs indexing

I am trying to improve performance on oracle 9i and 10g.
We use some queries that take up to 30 minutes to execute.
I heard that there are some products to cache query results.
Would this have any advantage over using indexes or materialized views?
Does anyone know any products that I can use to cache the results of this queries on disk?
Personally I think that by using the query result caching I would reduce the cpu time needed to process the query.
Is this true?

Your message post pushes all the wrong buttons starting with the fact that 9i and 10g are marketing labels not version numbers.
You don't tune queries by spending money and throwing resources at them. You tune them by identifying the problem queries, running explain plans, visualizing their output using DBMS_XPLAN, and addressing the root cause.
If you want help post full version numbers, the SQL statements, and the DBMS_XPLAN outputs.

Oracle 11g result cache and TimesTen

Oracle 11g has introduced the concept of result cache whereby the result set of frequently executed queries are stored in cache and used later when other users request the same query. This is different from caching the data blocks and exceuting the query over and over again.
Tom Kyte calls this just-in-time materialized view whereby the results are dynamically evaluated without DBA intervention
http://www.oracle.com/technology/oramag/oracle/07-sep/o57asktom.html
My point is that in view of utilities like result_cache and possible use of Solid State Disks in Oracle to speed up physical I/O etc is there any need for a product like TimesTen? It sounds to me that it may just asdd another layer of complexity?

Oracle result cache ia a useful tool but it is distinctly different from TimesTen. My understanding of Oracle's result cache is caching results set for seldom changing data like look up tables (currencies ID/code), reference data that does not change often (list of counter parties) etc. It would be pointless for caching result set where the underlying data changes frequently.
There is also another argument for SQL result cache in that if you are hitting high on your use of CPUs and you have enough of memory then you can cache some of the results set thus saving on your CPU cycles.
Considering the arguments about hard wired RDBMS and Solid State Disks (SSD), we can talk about it all day but having SSD does not eliminate the optimiser consideration for physical I/O. A table scan is a table scan whether data resides on SCSI or SSD disk. SSD will be faster but we are still performing physical IOs.
With regard to TimesTen, the product positioning is different. TimesTen is closer to middletier than Oracle. It is designed to work closely to application layer whereas Oracle has much wider purpose. For real time response and moderate volumes there is no way one can substitue TimesTen with any hard wired RDBMS. The request for result cache has been around for sometime. In areas like program trading and market data where the underlying data changes rapidly, TimesTen will come very handy as the data is real time/transient and the calculations have to be done almost realtime, with least complications from the execution engine. I fail to see how one can deploy result cache in this scenario. Because of the underlying change of data, Oracle will be forced to calculate the queries almost everytime and the result cache will be just wasted.
Hope this helps,
Mich

Oracle 11g/R2 Query Result Cache - Incremental Update

Hi,
In Oracle 11g/R2, I created replica of HR.Employees table & executed the following statement (+Although using SUM() function is non-logical in this case, but just testifying the result+)
STEP - 1
SELECT      /+ RESULT_CACHE */ employee_id, first_name, last_name, SUM(salary)*
FROM           HR.Employees_copy
WHERE      department_id = 20
GROUP BY      employee_id, first_name, last_name;
EMPLOYEE_ID      FIRST_NAME LAST_NAME     SUM(SALARY)
202           Pat           Fay          6000
201           Michael           Hartstein     13000
Elapsed: 00:00:00.01
Execution Plan
Plan hash value: 3837552314
| Id | Operation           | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT      | | 2 | 130 | 4 (25)| 00:00:01 |
| 1 | RESULT CACHE      | 3acbj133x8qkq8f8m7zm0br3mu | | | | |
| 2 | HASH GROUP BY      | | 2 | 130 | 4 (25)| 00:00:01 |
|* 3 | TABLE ACCESS FULL     | EMPLOYEES_COPY | 2 | 130 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------     Statistics
0 recursive calls
0 db block gets
0 consistent gets
0 physical reads
0 redo size
*690* bytes sent via SQL*Net to client
416 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed
STEP - 2
INSERT INTO HR.employees_copy
VALUES(200, 'Dummy', 'User','[email protected]',NULL, sysdate, 'MANAGER',5000, NULL,NULL,20);
STEP - 3
SELECT      /*+ RESULT_CACHE */ employee_id, first_name, last_name, SUM(salary)
FROM           HR.Employees_copy
WHERE      department_id = 20
GROUP BY      employee_id, first_name, last_name;
EMPLOYEE_ID      FIRST_NAME LAST_NAME SUM(SALARY)
202      Pat      Fay      6000
201      Michael      Hartstein      13000
200      Dummy User      5000
Elapsed: 00:00:00.03
Execution Plan
Plan hash value: 3837552314
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT |          | 3 | 195 | 4 (25)| 00:00:01 |
| 1 | RESULT CACHE | 3acbj133x8qkq8f8m7zm0br3mu | | | | |
| 2 | HASH GROUP BY | | 3 | 195 | 4 (25)| 00:00:01 |
|* 3 | TABLE ACCESS FULL| EMPLOYEES_COPY | 3 | 195 | 3 (0)| 00:00:01 |
     Statistics
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
*714* bytes sent via SQL*Net to client
416 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3 rows processed
In the execution plan of STEP-3, against ID-1 the operation RESULT CACHE is shown which shows the result has been retrieved directly from Result cache. Does this mean that Oracle Server has Incrementally Retrieved the resultset?
Because, before the execution of STEP-2, the cache contained only 2 records. Then 1 record was inserted but after STEP-3, a total of 3 records was returned from cache. Does this mean that newly inserted row is retrieved from database and merged to the cached result of STEP-1?
If Oracle server has incrementally retrieved and merged newly inserted record, what mechanism is being used by the Oracle to do so?
Regards,
Wasif
Edited by: 965300 on Oct 15, 2012 12:25 AM

965300 wrote:
Hi,
In Oracle 11g/R2, I created replica of HR.Employees table & executed the following statement (+Although using SUM() function is non-logical in this case, but just testifying the result+)
STEP - 1
SELECT      /+ RESULT_CACHE */ employee_id, first_name, last_name, SUM(salary)*
FROM           HR.Employees_copy
WHERE      department_id = 20
GROUP BY      employee_id, first_name, last_name;
EMPLOYEE_ID      FIRST_NAME LAST_NAME     SUM(SALARY)
202           Pat           Fay          6000
201           Michael           Hartstein     13000
Elapsed: 00:00:00.01
Execution Plan
Plan hash value: 3837552314
| Id | Operation           | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT      | | 2 | 130 | 4 (25)| 00:00:01 |
| 1 | RESULT CACHE      | 3acbj133x8qkq8f8m7zm0br3mu | | | | |
| 2 | HASH GROUP BY      | | 2 | 130 | 4 (25)| 00:00:01 |
|* 3 | TABLE ACCESS FULL     | EMPLOYEES_COPY | 2 | 130 | 3 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------     Statistics
0 recursive calls
0 db block gets
0 consistent gets
0 physical reads
0 redo size
*690* bytes sent via SQL*Net to client
416 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed
STEP - 2
INSERT INTO HR.employees_copy
VALUES(200, 'Dummy', 'User','[email protected]',NULL, sysdate, 'MANAGER',5000, NULL,NULL,20);
STEP - 3
SELECT      /*+ RESULT_CACHE */ employee_id, first_name, last_name, SUM(salary)
FROM           HR.Employees_copy
WHERE      department_id = 20
GROUP BY      employee_id, first_name, last_name;
EMPLOYEE_ID      FIRST_NAME LAST_NAME SUM(SALARY)
202      Pat      Fay      6000
201      Michael      Hartstein      13000
200      Dummy User      5000
Elapsed: 00:00:00.03
Execution Plan
Plan hash value: 3837552314
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT |          | 3 | 195 | 4 (25)| 00:00:01 |
| 1 | RESULT CACHE | 3acbj133x8qkq8f8m7zm0br3mu | | | | |
| 2 | HASH GROUP BY | | 3 | 195 | 4 (25)| 00:00:01 |
|* 3 | TABLE ACCESS FULL| EMPLOYEES_COPY | 3 | 195 | 3 (0)| 00:00:01 |
     Statistics
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
*714* bytes sent via SQL*Net to client
416 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
3 rows processed
In the execution plan of STEP-3, against ID-1 the operation RESULT CACHE is shown which shows the result has been retrieved directly from Result cache. Does this mean that Oracle Server has Incrementally Retrieved the resultset?
Because, before the execution of STEP-2, the cache contained only 2 records. Then 1 record was inserted but after STEP-3, a total of 3 records was returned from cache. Does this mean that newly inserted row is retrieved from database and merged to the cached result of STEP-1?
If Oracle server has incrementally retrieved and merged newly inserted record, what mechanism is being used by the Oracle to do so?
Regards,
Wasif
Edited by: 965300 on Oct 15, 2012 12:25 AMNo, the RESULT CACHE operation doesn't necessarily mean that the results are retrieved from there. It could be being
written to there.
Look at the number of consistent gets: it's zero in the first step (I assume you had already run this query before) and I would
conclude that the data is being read from the result cache.
In the third step there are 4 consistent gets. I would conclude that the data is being written to the result cache, a fourth step repeating
the SQL should show zero consistent gets and that would be the results being read.

Oracle result cache and functions

Hi All,
I am on 11.2 in Linux.
I want to use Oracle's result cache to cache results of (user defined) functions, which we use in SELECT commands.
My question is, does result caching work for deterministic and non-deterministic functions ?
Just curious, how Oracle keeps track of changes being made which affect a function's return value?
Thoughts please.
Thanks in advance

I want to ... cache results of (user defined) functions, which we use in SELECT commands.You have four choices:
1. Subquery caching - (wrap function call in SELECT) useful for repeated function calls in a single SELECT
2. Marking function as DETERMINISTIC - inconsistent results across versions, deterministic best reserved for function-based indexes only
3. Result Cache
4. Move function logic out of function and inline to the main SQL statement.
The biggest downside of any function call that is inline to SQL is that it bypasses the read consistency mechanism, actually that's probably the second biggest downside. The biggest downside is normally that their misuse kills performance.
If your function itself contains SQL then you should seriously reconsider whether you should be using a function.
does result caching work for deterministic and non-deterministic functions ?Result cache knows nothing about determinism so yes it should be applied regardless.
Oracle keeps track of changes being made which affect a function's return value?See v$result_cache_dependency.
The mechanism is very blunt, there is no fine-grained tracking of data changes that may affect your result.
It's as simple as function F1 relies on table T1. If the data in table T1 changes, invalidate the results in the result cache for F1.

Does OCI client result cache and oracle UCP work together?

I'm using Oracle 11.2.1.0. I've set up FCF and enabled OCI result cache on server side, so on client side, I'm using UCP for failover.
this is my datasource configuration:
<Resource name="jdbc/MyPool"
auth="Container"
factory="oracle.ucp.jdbc.PoolDataSourceImpl"
type="oracle.ucp.jdbc.PoolDataSource"
connectionFactoryClassName="oracle.jdbc.pool.OracleDataSource"
url="jdbc:oracle:oci:@dbhost:1521/myDb"
user="db_user"
password="db_password"
fastConnectionFailoverEnabled="true"
onsConfiguration=""
connectionPoolName="dbPool"
initialPoolSize="5"
minPoolSize="5"
maxPoolSize="25"
connectionWaitTimeout="10000"
inactiveConnectionTimeout="120000"
abandonConnectionTimeout="60"
validateConnectionOnBorrow="true"
sqlForValidateConnection="select user from dual"
maxStatements="30"/>
I've enabled OCI client result cache.
I use /*+ result_cache */ in my query to take advantage of the result cache.
so I execute the following scenario:
i) select /*+ result_cache */ value from myTable where id=1; (this returns a result.)
ii) update myTable to set a different value for id=1 record;
iii) run select query again; (this should return a different result. oci result cache gets updated when table changes.)
if I take out
"sqlForValidateConnection" and/or "validateConnectionOnBorrow" (i.e. disable sql validation on borrow), the 2nd query after table update doesn't show the latest result. it's still showing the old query result.
is this a bug? that UCP validation on borrow has an impact on OCI result cache function? this doesn't happen if using dbcp java connection pooling with OCI result cache.

it turns out I ran the test against an oracle server that doesnt have FCF configured, nor ONS.
once i switched to a correct oracle cluster, my test passed.

Oracle 11g Result Cache

Hi,
I have read that there is SGA component called Result Cache. According to documentation:
The result cache buffers query results. If a query is run that
already has results in the result cache, the database returns
results from the result cache instead of rerunning the query. This
speeds up the execution of frequently run queries.
What happens when data in tables which are called by the query change. I think the old data still will be in cache and I always get the old data.
Peter D.

Hi Peter
What happens when data in tables which are called by
the query change. I think the old data still will be in
cache and I always get the old data.The server result cache can return old data only for distributed queries (i.e. queries also retrieving data from other databases).
All local queries return the correct data. To do so, the cache entries are invalidated as required.
HTH
Chris Antognini
Author of Troubleshooting Oracle Performance, Apress 2008 (http://top.antognini.ch)

Result Cache Oracle 11gR2

Hi all,
Currently I have some problems with result cache, or maybe I don't understand this feature properly.
I'm trying to switch off the bypass mode, and I'm not able to do this:
SQL> select dbms_result_cache.status from dual;
STATUS
BYPASS
SQL> exec dbms_result_cache.bypass(FALSE);
PL/SQL procedure successfully completed.
SQL> select dbms_result_cache.status from dual;
STATUS
BYPASS
SQL> show parameter result
NAME TYPE VALUE
client_result_cache_lag big integer 3000
client_result_cache_size big integer 0
result_cache_max_result integer 5
result_cache_max_size big integer 0
result_cache_mode string MANUAL
result_cache_remote_expiration integer 0
SQL> alter system set result_cache_max_size=2M scope=both;
System altered.
SQL> show parameter result
NAME TYPE VALUE
client_result_cache_lag big integer 3000
client_result_cache_size big integer 0
result_cache_max_result integer 5
result_cache_max_size big integer 0
result_cache_mode string MANUAL
result_cache_remote_expiration integer 0
SQL> alter system set result_cache_max_size=2M scope=spfile;
System altered.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
Total System Global Area 523108352 bytes
Fixed Size 1337632 bytes
Variable Size 465569504 bytes
Database Buffers 50331648 bytes
Redo Buffers 5869568 bytes
Database mounted.
Database opened.
SQL> show parameter result
NAME TYPE VALUE
client_result_cache_lag big integer 3000
client_result_cache_size big integer 1G
result_cache_max_result integer 5
result_cache_max_size big integer 0
result_cache_mode string MANUAL
result_cache_remote_expiration integer 0
SQL> select dbms_result_cache.status from dual;
STATUS
BYPASS
SQL> set serveroutput on;
SQL> exec dbms_result_cache.memory_report
R e s u l t C a c h e M e m o r y R e p o r t
[Parameters]
Block Size = 1K bytes
Maximum Cache Size = 0 bytes (0 blocks)
Maximum Result Size = 0 bytes (0 blocks)
[Memory]
Total Memory = 9440 bytes [0.004% of the Shared Pool]
... Fixed Memory = 9440 bytes [0.004% of the Shared Pool]
... Dynamic Memory = 0 bytes [0.000% of the Shared Pool]
PL/SQL procedure successfully completed.
SQL>
Is there something what I missed?
Thanks for any advices.
Regards,
Piotr

A little bit more theory:
The result cache resides in the Shared pool. Because the database was managing its memory automatically (parameter memory_target was set) and no one was working with this environment, the database didn't allocate yet enough space for shared pool to give some space for result cache. I had to set min value for shared pool to force the database to automatically allocate some space to shared pool during start up and never make shared pool smaller than specified value.
Hope that this explanation help other people :)
Regards,
Petrus

Using the Client Result Cache

Hello everyone,
I have a question regarding the use of the client result cache but first of all here are the informations about my database:
SQL> SELECT * FROM v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0    Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
I have installed the Oracle Client Tools on my clientmachine. It has a tnsnames.ora like this:
ORCL =
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = FEA11-119SRV)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = orcl.local)
The Client Result Cache is configured in the sqlnet.ora.
ADR_BASE = /u01/app/oracle
OCI_RESULT_CACHE_MAX_SIZE= 2048000
OCI_RESULT_CACHE_MAX_RSET_SIZE = 1024000
NAMES.DIRECTORY_PATH = (EZCONNECT, TNSNAMES, HOSTNAME)
The Databaseserver is configured like that:
SQL> col name format a30
SQL> col value format a30
SQL> SELECT name, value
2 FROM   v$system_parameter
3 WHERE name LIKE '%result_cache%';
NAME                   VALUE
result_cache_mode           MANUAL
result_cache_max_size           0
result_cache_max_result        5
result_cache_remote_expiration 0
client_result_cache_size       1073741824
client_result_cache_lag        3000
After configuring client an server I try the followign SQL-Statement on the clientmachine:
sqlplus oracle/password@orcl
set autotrace traceonly explain
SELECT /*+ result_cache */ *
FROM testtable;
SQL
The execution plan show two operations: "SELECT STATEMENT" and "TABLE ACCESS FULL" but no the "RESULT CACHE" operation.
Did I miss something?
Any help would be appreciated
Florian W.

result_cache_max_size           0
That means the result cache is disabled. You need to set it to a non-zero value. That is the maximum ammount of memory, in bytes, the database will allocate on the shared pool to dedicate it to the result cache for all requests.
By the way, OCI_RESULT_CACHE_MAX_SIZE is optional. By default the sessions will have the maximum size they can occupy on the cache determined by CLIENT_RESULT_CACHE parameter, the client (OCI) side parameters override that.
result_cache_mode           MANUAL
Another thing to consider is RESULT_CACHE_MODE in MANUAL, that will cause only the statements with the RESULT_CACHE hint on it to be cached on the result cache. You can also set result cache to mode FORCE on specific tables with alter table command.
Regards

Result cache not working?

Hi,
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> show parameter result;
NAME TYPE VALUE
client_result_cache_lag big integer 3000
client_result_cache_size big integer 0
result_cache_max_result integer 5
result_cache_max_size big integer 10M
result_cache_mode string MANUAL
result_cache_remote_expiration integer 0
The above are the initialization parameters set and the DB version.
Now i have created a table as
create table objects as select * from dba_objects;
then issued the following query.
select /* result_cache */ object_Type,count(*) from objects group by object_type;
it appears that the results of the above query is not cached in the result cache. using
set autotrace traceonly explain confirms that there is no result cache or the CACHE_ID in the explain plan. also the v$result_cache_statistics confirm the same.
But after this when i issued the following statement.
alter session set result_cache_mode=force;
the same below sql statement again
select /* result_cache */ object_Type,count(*) from objects group by object_type;
it appears that now the result cache is being used.
My question is despite using the result_cache hint and trying the above statement when the result_cache_mode=auto/manual. The result cache is not being used or the results of the SQL statements are not being cached at all despite using the result_cache hint and the table being not used at all. and if i use the result_cache_mode=force then the result cache is being used.
Can any one please explain this behavior. Cursor_sharing is set to EXACT. and i am issuing the same SQL statement without any changes at all.
Thanks,

There is a syntax problem with your queries:
select /* result_cache */.... is just a comment, not a hint. For creating a hint, you need "+": select /*+ result_cache */....

Result Cache hint in Oracle 11 g

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