Montag, 14. September 2009

result cache not enabled for owner SYS and SYSTEM

EDIT: the original title of this blog was "result cache not enabled in SYSTEM and SYSAUX Tablespace".
After a totally correct post from Coskan I had to rework it totally. I mixed up the problem and conclusio so much it was totally messed up.

I hope this one is the better one:




During some Tests with result cache in 11gR2 I discovered a small docu bug.
You can still see the bug in the 11gR1 docu:

You cannot cache results when you use the following database objects or functions in your SQL query:

  • Dictionary and temporary tables

  • Sequence CURRVAL and NEXTVAL pseudo columns

  • SQL functions current_date, current_timestamp, local_timestamp, userenv/sys_context (with non-constant variables), sys_guid, sysdate, and sys_timestamp

  • Non-deterministic PL/SQL functions


In 11gR2 it sounds slightly different: 7.6.4.2 Additional Requirements for the Result Cache:

You cannot cache results when the following objects or functions are in a query:

  • Temporary tables and tables in the SYS or SYSTEM schemas

  • Sequence CURRVAL and NEXTVAL pseudo columns

  • SQL functions CURRENT_DATE, CURRENT_TIMESTAMP, LOCAL_TIMESTAMP, USERENV/SYS_CONTEXT (with non-constant variables), SYS_GUID, SYSDATE, andSYS_TIMESTAMP


for those of you who want to run the testcase:

create tablespace berx1 datafile '+DG' SIZE 50M;
create user berx1 identified by berx1;
grant connect to berx1;
grant unlimited tablespace to berx1;

create table sys.berx1_1 tablespace system as select * from dual;
create table sys.berx1_2 tablespace sysaux as select * from dual;
create table sys.berx1_3 tablespace berx1 as select * from dual;
create table system.berx1_4 tablespace system as select * from dual;
create table system.berx1_5 tablespace sysaux as select * from dual;
create table system.berx1_6 tablespace berx1 as select * from dual;
create table berx1.berx1_7 tablespace system as select * from dual;
create table berx1.berx1_8 tablespace sysaux as select * from dual;
create table berx1.berx1_9 tablespace berx1 as select * from dual;
grant select on sys.berx1_1 to berx1;
grant select on sys.berx1_2 to berx1;
grant select on sys.berx1_3 to berx1;
grant select on system.berx1_4 to berx1;
grant select on system.berx1_5 to berx1;
grant select on system.berx1_6 to berx1;

set autotrace on

-- run as user sys, system and berx1:

select /*+ result_cache */ * from sys.berx1_1;
select /*+ result_cache */ * from sys.berx1_2;
select /*+ result_cache */ * from sys.berx1_3;
select /*+ result_cache */ * from system.berx1_4;
select /*+ result_cache */ * from system.berx1_5;
select /*+ result_cache */ * from system.berx1_6;
select /*+ result_cache */ * from berx1.berx1_7;
select /*+ result_cache */ * from berx1.berx1_8;
select /*+ result_cache */ * from berx1.berx1_9;


my results are reflected in this matrix:





berx1_1 berx1_2 berx1_3 berx1_4 berx1_5 berx1_6 berx1_7 berx1_8 berx1_9
sys N N N N N N Y Y Y
system N N N N N N Y Y Y
berx1 N N N N N N Y Y Y


So in my testcase it's not dependend of the schema (or the data dichtionary), but the tablespace.
This issue is addressed in BUG:8558309 and fixed in the latest docu :)

I know, I should never create any objects in SYS or SYSTEM schema. Especially if you want this object to be cached in result cache.

Once again thank you Coskan for showing my ridiculous error.
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