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Effect of modifying init parameters from PDBs

Y.Ramlet
Y.Ramlet Member Posts: 258 Bronze Badge
edited Mar 20, 2019 11:08PM in Multitenant

Oracle DB version: 12.2

OS : Oracle Linux 7.6

I have a question on the effect of modifying init.ora parameters while logged in to PDB .

Demo below:

Initially at Container DB level , the SGA_TARGET was set to 2688 MB and DB_CACHE_SIZE was set to 0 MB (Exhibit1)

Then I logged into a PDB using ALTER SESSION SET CONTAINER and modified SGA_TARGET to 2000MB and DB_CACHE_SIZE to 200MB (Exhibit2)

As you can see below in Exhibit3 , when I log into container DB , the values remain unchanged.

So, what does this all mean ? Does this mean PDB3 now has dedicated 2000MB of SGA_TARGET and 200MB of DB_CACHE_SIZE ?

Exhibit1--- Connected to container DB(root)SQL> show parameter db_cache_sizeNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------db_cache_size                 big integer 0SQL>SQL>SQL> show parameter sga_targetNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------sga_target                 big integer 2688MSQL>SQL>SQL>SQL> show con_idCON_ID------------------------------1SQL>Exhibit2--- Connecting to a PDB and modifying SGA_TARGET and DB_CACHE_SIZESQL> alter session set container=PDB3;Session altered.SQL> alter system set db_cache_size=200m;System altered.SQL> alter system set sga_target=2000m;System altered.SQL> show con_idCON_ID------------------------------3SQL> show parameter db_cache_sNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------db_cache_size                 big integer 200MSQL>SQL>SQL> show parameter sga_tNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------sga_target                 big integer 2000MSQL>Exhibit3--- exited from the above terminal and logging in to container DB(root) again--- The values seem unchanged (same as Exhibit 1) when I check from Container DB(root) level$ sqlplus / as sysdbaSQL*Plus: Release 12.2.0.1.0 Production on Tue Mar 5 11:58:43 2019Copyright (c) 1982, 2016, Oracle.  All rights reserved.Connected to:Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit ProductionSQL> show parameter sga_tNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------sga_target                 big integer 2688MSQL>SQL>SQL> show parameter db_cache_sizeNAME                     TYPE     VALUE------------------------------------ ----------- ------------------------------db_cache_size                 big integer 0
Y.Ramlet

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