Search My Oracle Blog

Custom Search

06 December, 2016

12.2 New Features -- 5 : Memory Parameters for Pluggable Database

12.2 allows Instance Memory parameters to be configured at the PDB level.

[timestamp in UTC]

[oracle@HKCORCL ~]$ sqlplus '/ as sysdba'

SQL*Plus: Release 12.2.0.1.0 Production on Tue Dec 6 13:56:28 2016

Copyright (c) 1982, 2016, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
allow_group_access_to_sga            boolean     FALSE
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     TRUE
sga_max_size                         big integer 2544M
sga_min_size                         big integer 0
sga_target                           big integer 2544M
unified_audit_sga_queue_size         integer     1048576
SQL> show parameter db_cach

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_cache_advice                      string      ON
db_cache_size                        big integer 0
SQL>


Those are parameters set at the CDB level. Let's see the PDB.

SQL> alter session set container = PDB1;

Session altered.

SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
allow_group_access_to_sga            boolean     FALSE
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     TRUE
sga_max_size                         big integer 2544M
sga_min_size                         big integer 0
sga_target                           big integer 0
unified_audit_sga_queue_size         integer     1048576
SQL> show parameter db_cache

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_cache_advice                      string      ON
db_cache_size                        big integer 0
SQL> alter system set db_cache_size=400M;

System altered.

SQL>
SQL> alter system set sga_target=512M;
alter system set sga_target=512M
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-56750: invalid value 536870912 for parameter sga_target; must be larger
than 200% of parameter db_cache_size


SQL> alter system set sga_target=810M;

System altered.

SQL> alter system set shared_pool_size=256M;

System altered.

SQL> show parameter db_cache

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_cache_advice                      string      ON
db_cache_size                        big integer 400M
SQL> show parameter sga_target

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_target                           big integer 810M
SQL> show parameter shared_pool

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
shared_pool_reserved_size            big integer 26004684
shared_pool_size                     big integer 256M
SQL>
SQL> alter system set pga_aggregate_target=128M;

System altered.

SQL>


Returning to the CDB ...

SQL> connect / as sysdba
Connected.
SQL> show parameter db_cache

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_cache_advice                      string      ON
db_cache_size                        big integer 0
SQL> show parameter sga_target

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_target                           big integer 2544M
SQL> show parameter shared_pool

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
shared_pool_reserved_size            big integer 26004684
shared_pool_size                     big integer 0
SQL> show parameter pga_aggergate_target
SQL> show parameter pga_aggregate_target

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target                 big integer 1775294400
SQL>


Thus, multiple PDBs can have their own private target and limits (even an SGA_MIN_SIZE) all shared within the single instance that they co-exist in.
Note : The requirement is that MEMORY_TARGET is to be not set.
.
.
.

3 comments:

JAW said...

Very good

Rijesh M Chandran said...

Does that mean the common SGA is now split into different pools for individual PDBs? Or is it some sort of guaranteed minimum memory sizes for the PDBs from the common SGA pool?

Thanks,
Rijesh

Hemant K Chitale said...

Rijesh,
I don't see it has a hard-split. It is a specification of minimum size for each PDB.

Hemant

Aggregated by orafaq.com

Aggregated by orafaq.com
This blog is being aggregated by orafaq.com