Thursday, June 27, 2013

Oracle 12c New Features - Extended Datatypes VARCHAR2 32767 bytes

In Oracle 12c it is now possible to create VARCHAR2, NVARCHAR2, and RAW attributes of size 32767 bytes.

This is controlled by new parameter MAX_STRING_SIZE.  The value of the parameter defaults to STANDARD, but if you set it to EXTENDED you can use the expanded variable size.  Consider this carefully, as increased column sizes will have effects on any applications that use the data in variables and parameters and can limit the use of partitions and indexes on the extended datatypes.

In addition to setting MAX_STRING_SIZE=EXTENDED you also need to start the database in "upgrade" mode and run utl32k.sql  Also be aware that if you are running CDB / PDB you may need to upgrade them individually, including the SEED DB.

SQL> alter system set max_string_size=EXTENDED scope=spfile;

System altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup upgrade
ORACLE instance started.

Total System Global Area 1636814848 bytes
Fixed Size                  2288968 bytes
Variable Size            1056965304 bytes
Database Buffers          570425344 bytes
Redo Buffers                7135232 bytes
Database mounted.
Database opened.
SQL> @utl32k.sql

Session altered.

DOC>#######################################################################
DOC>#######################################################################
DOC>   The following statement will cause an "ORA-01722: invalid number"
DOC>   error if the database has not been opened for UPGRADE.
DOC>
DOC>   Perform a "SHUTDOWN ABORT"  and
DOC>   restart using UPGRADE.
DOC>#######################################################################
DOC>#######################################################################
DOC>#

no rows selected

DOC>#######################################################################
DOC>#######################################################################
DOC>   The following statement will cause an "ORA-01722: invalid number"
DOC>   error if the database does not have compatible >= 12.0.0
DOC>
DOC>   Set compatible >= 12.0.0 and retry.
DOC>#######################################################################
DOC>#######################################################################
DOC>#

PL/SQL procedure successfully completed.


Session altered.


0 rows updated.


Commit complete.


System altered.


PL/SQL procedure successfully completed.


Commit complete.


System altered.


Session altered.


PL/SQL procedure successfully completed.

No errors.

Session altered.


PL/SQL procedure successfully completed.


Commit complete.


Package altered.


TIMESTAMP
--------------------------------------------------------------------------------
COMP_TIMESTAMP UTLRP_BGN  2013-06-28 10:47:30

DOC>   The following PL/SQL block invokes UTL_RECOMP to recompile invalid
DOC>   objects in the database. Recompilation time is proportional to the
DOC>   number of invalid objects in the database, so this command may take
DOC>   a long time to execute on a database with a large number of invalid
DOC>   objects.
DOC>
DOC>   Use the following queries to track recompilation progress:
DOC>
DOC>   1. Query returning the number of invalid objects remaining. This
DOC>      number should decrease with time.
DOC>         SELECT COUNT(*) FROM obj$ WHERE status IN (4, 5, 6);
DOC>
DOC>   2. Query returning the number of objects compiled so far. This number
DOC>      should increase with time.
DOC>         SELECT COUNT(*) FROM UTL_RECOMP_COMPILED;
DOC>
DOC>   This script automatically chooses serial or parallel recompilation
DOC>   based on the number of CPUs available (parameter cpu_count) multiplied
DOC>   by the number of threads per CPU (parameter parallel_threads_per_cpu).
DOC>   On RAC, this number is added across all RAC nodes.
DOC>
DOC>   UTL_RECOMP uses DBMS_SCHEDULER to create jobs for parallel
DOC>   recompilation. Jobs are created without instance affinity so that they
DOC>   can migrate across RAC nodes. Use the following queries to verify
DOC>   whether UTL_RECOMP jobs are being created and run correctly:
DOC>
DOC>   1. Query showing jobs created by UTL_RECOMP
DOC>         SELECT job_name FROM dba_scheduler_jobs
DOC>            WHERE job_name like 'UTL_RECOMP_SLAVE_%';
DOC>
DOC>   2. Query showing UTL_RECOMP jobs that are running
DOC>         SELECT job_name FROM dba_scheduler_running_jobs
DOC>            WHERE job_name like 'UTL_RECOMP_SLAVE_%';
DOC>#

PL/SQL procedure successfully completed.


TIMESTAMP
--------------------------------------------------------------------------------
COMP_TIMESTAMP UTLRP_END  2013-06-28 10:47:32

DOC> The following query reports the number of objects that have compiled
DOC> with errors.
DOC>
DOC> If the number is higher than expected, please examine the error
DOC> messages reported with each object (using SHOW ERRORS) to see if they
DOC> point to system misconfiguration or resource constraints that must be
DOC> fixed before attempting to recompile these objects.
DOC>#

OBJECTS WITH ERRORS
-------------------
                  0

DOC> The following query reports the number of errors caught during
DOC> recompilation. If this number is non-zero, please query the error
DOC> messages in the table UTL_RECOMP_ERRORS to see if any of these errors
DOC> are due to misconfiguration or resource constraints that must be
DOC> fixed before objects can compile successfully.
DOC>#

ERRORS DURING RECOMPILATION
---------------------------
                          0


Function created.


PL/SQL procedure successfully completed.


Function dropped.

...Database user "SYS", database schema "APEX_040200", user# "98" 10:47:42
...Compiled 0 out of 2998 objects considered, 0 failed compilation 10:47:43
...263 packages
...255 package bodies
...453 tables
...11 functions
...16 procedures
...3 sequences
...458 triggers
...1322 indexes
...207 views
...0 libraries
...6 types
...0 type bodies
...0 operators
...0 index types
...Begin key object existence check 10:47:43
...Completed key object existence check 10:47:43
...Setting DBMS Registry 10:47:43
...Setting DBMS Registry Complete 10:47:43
...Exiting validate 10:47:43

PL/SQL procedure successfully completed.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 1636814848 bytes
Fixed Size                  2288968 bytes
Variable Size            1056965304 bytes
Database Buffers          570425344 bytes
Redo Buffers                7135232 bytes
Database mounted.
Database opened.
SQL> show parameter max_string_size

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
max_string_size                      string      EXTENDED


SQL> connect test/test
Connected.
SQL> create table employee (emp_id integer, emp_name varchar2(20), life_story varchar2(32000));

Table created.

SQL> desc employee
 Name                                      Null?  Type
 ----------------------------------------- ------ ---------------
 EMP_ID                                           NUMBER(38)
 EMP_NAME                                         VARCHAR2(20)
 LIFE_STORY                                       VARCHAR2(32000)

SQL> select segment_name, segment_type from user_segments;

no rows selected

SQL> insert into employee values (1,'John','Wage Slave');

1 row created.

SQL> commit;

Commit complete.

Looking at the segments that exist we can see that by creating a TABLE with an extended VARCHAR2 column this was actually implemented using a TABLE, LOBSEGMENT, and associated LOBINDEX.

SQL> select segment_name, segment_type from user_segments;

SEGMENT_NAME                          SEGMENT_TYPE
------------------------------------- ---------------------------
EMPLOYEE                              TABLE
SYS_IL0000092103C00003$$              LOBINDEX
SYS_LOB0000092103C00003$$             LOBSEGMENT