Script for creating a multitenant database with dbca

Prerequisites:

You have a valid Oracle 19c installation in a server

You have set your Oracle environment already, so that your PATH, ORACLE_SID etc already exists when you execute your script

The script called run_dbca.sh:

#!/bin/bash
start=$(date +%s.%N)
export GLOGFILE=run_dbca.log
touch ${GLOGFILE}
chmod 666 ${GLOGFILE}
exec 1> ${GLOGFILE} 2>&1
echo "Now running run_dbca.sh"
echo "Resetting oratab..."
echo '' > /etc/oratab
if [ $? -ne 0 ]; then
 echo "Could not erase oratab. Exit."
 exit 1
else
 echo "oratab erased. Continuing..."
fi
export instanceAlive=`ps -ef| grep pmon | grep -v grep |awk '{ print $8}' | cut -f 3 -d"_"`

if [ ! -z ${instanceAlive} ]; then
 echo "Instance for database $ORACLE_SID is already running. Shut it down first"
 exit 1
fi
dbca -createDatabase -responsefile ./${ORACLE_SID}.rsp -silent
echo "Finished running run_dbca.sh"
dur=$(echo "$(date +%s.%N) - $start" | bc)
printf "Total execution time for run_dbca.sh: %.6f seconds\n" $dur
exit 0

The response file can be seen below. I saved it in a file called cdb.rsp and put it in the same directory.

I commented out most instructions, as they are not needed.

The original template db_install.rsp is delivered by default with your oracle installation and resides in your $ORACLE_HOME/install/response.

#-------------------------------------------------------------------------------
# Do not change the responseFileVersion diretive!
#-------------------------------------------------------------------------------
responseFileVersion=/oracle/assistants/rspfmt_dbca_response_schema_v19.0.0
gdbName=cdb.oric.no
sid=cdb
createAsContainerDatabase=true
numberOfPDBs=1
pdbName=pdb1
useLocalUndoForPDBs=true
pdbAdminPassword=mysecretpassword
templateName=New_Database.dbt
sysPassword=mysyspassword
systemPassword=mysystempassword
datafileDestination=/data01/oradata/cdb
recoveryAreaDestination=/data02/fra
characterSet=AL32UTF8
initParams=max_pdbs=3,db_create_file_dest_size=1024GB
memoryPercentage=75
automaticMemoryManagement=false
enableArchive=true
redoLogFileSize=2048
dbOptions=JSERVER:false,DV:false,ORACLE_TEXT:false,IMEDIA:false,CWMLITE:false,SPATIAL:false,OMS:false,APEX:false

Execute the script like this:

./run_dbca.sh

Follow the progression of the creation in the log run_dbca.log:

tail -f run_dbca.log

Sources:

Oracle 19c documentation: About creating a database with dbca

Oracle 19c documentation: Managing templates with dbca

Oracle-Base.com: Multitenant : Create and Configure a Pluggable Database (PDB) in Oracle Database 12c Release 1 (12.1) - still a relevant and good source.

Oracle-base.com: a dbca template

Oracle-base.com: Database Configuration Assistant (DBCA) : Creating Databases in Silent Mode

Solution for [DBT-10317] Specified SID Name (SID) already exists when running dbca

When running dbca, for example like this:

dbca -createDatabase -responsefile ./cdb.rsp -silent
[FATAL] [DBT-10317] Specified SID Name (cdb) already exists.
   ACTION: Specify a different SID Name that does not already exist.

There are two potential reasons for the error:

1. you have a /etc/oratab which has an entry, for example:

cdb:/installedsw1/oracle/product/Ora19c:Y

2. your instance is running.

Solution to case 1: remove entry

Solution to case 2: shutdown the instance

Rerun dbca and it will now proceed as expected.

Syntax for switching over a container database using data guard broker

Here I am switching over a container database called cdb, to the standby server which is running a container database with unique name cdb_stby1.

First, view the configuration:

DGMGRL> show configuration

Configuration - DGConfig1

  Protection Mode: MaxPerformance
  Members:
  cdb       - Primary database
    cdb_stby1 - Physical standby database

Fast-Start Failover:  Disabled

Configuration Status:
SUCCESS   (status updated 84 seconds ago)

Perform the switchover:

DGMGRL> switchover to 'cdb_stby1';

Typical output from a successful switchover:

Performing switchover NOW, please wait...
Operation requires a connection to database "cdb_stby1"
Connecting ...
Connected to "cdb_stby1"
Connected as SYSDBA.
New primary database "cdb_stby1" is opening...
Operation requires start up of instance "cdb" on database "cdb"
Starting instance "cdb"...
Connected to an idle instance.
ORACLE instance started.
Connected to "cdb"
Database mounted.
Switchover succeeded, new primary is "cdb_stby1"

If I wish to switch back, make sure you log on to whichever server is running your primary database at the time.
(DO NOT use os authentication with dgmgrl / as sysdba, it will throw an error)

dgmgrl sys@cdb_stby1 as sysdba
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Thu Sep 7 15:27:27 2023
Version 19.20.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

Welcome to DGMGRL, type "help" for information.
Password:
Connected to "cdb_stby1"
Connected as SYSDBA.
DGMGRL> show configuration;

Configuration - DGConfig1

  Protection Mode: MaxPerformance
  Members:
  cdb_stby1 - Primary database
    cdb       - Physical standby database

Fast-Start Failover:  Disabled

Configuration Status:
SUCCESS   (status updated 46 seconds ago)

DGMGRL> switchover to cdb
Performing switchover NOW, please wait...
Operation requires a connection to database "cdb"
Connecting ...
Connected to "cdb"
Connected as SYSDBA.
New primary database "cdb" is opening...
Operation requires start up of instance "cdb" on database "cdb_stby1"
Starting instance "cdb"...
Connected to an idle instance.
ORACLE instance started.
Connected to "cdb_stby1"
Database mounted.
Switchover succeeded, new primary is "cdb"

How to extract all datafile names without path using substr and instr functions

select trim(
            substr(file_name,
                (instr(file_name,'/', -1, 1) +1)
                )
               )  "file name"
from  dba_data_files;

Result:

file name
system01.dbf
sysaux01.dbf
undotbs01.dbf
users01.dbf
appl_data.dbf

More on how to display the current container in a multitenant database

My listener is listening for connections to a service called "myservice1", which runs out of the pluggable database "pdb1":

lsnrctl status
Service "pdb1" has 1 instance(s). <-- the default service for the pluggable database
  Instance "cdb", status READY, has 1 handler(s) for this service...

Service "myservice1" has 1 instance(s). <-- service defined by the DBA
  Instance "cdb", status READY, has 1 handler(s) for this service...

In the code snippet below, I am executing a script called disp_session.sql which will

connecting directly to a service served by the listener

switching schema within my session

The following will display the username, current schema, and the service my connction is connecting to:

alter session set current_schema=scott;
set lines 200
col service format a20
col container format a20
col username format a20
col "container ID" format a20
col schemaname format a20
select sys_context ('userenv','SERVICE_NAME')   service,
       sys_context ('userenv','CON_NAME')       container,
       sys_context ('userenv','CON_ID')         "container ID",
       sys_context ('userenv','CURRENT_USER')   username,
       sys_context ('userenv','CURRENT_SCHEMA') schemaname
from dual;

oracle@server1.oric.no:[cdb]# sqlplus system@myservice1 @disp_session.sql

Session altered.

SERVICE              CONTAINER            container ID         USERNAME             SCHEMANAME
-------------------- -------------------- -------------------- -------------------- --------------------
myservice1           pdb1                 4                    SYSTEM               SCOTT

Useful information when debugging client connections ;-)

How to exchange a line in a text file with a different one, when using double quotation marks in the text itself?

The following sed command will exchange the string

initParams=

with

initParams=undo_tablespace=UNDOTBS1,sga_target=9GB,db_block_size=32768BYTES,control_files=\"\/u02\/oradata\/{DB_UNIQUE_NAME}\/control01.ctl\"\,\"\/recovery\/fra\/{DB_UNIQUE_NAME}\/control01.ctl\"),db_recovery_file_dest=\/recovery\/fra\/{DB_UNIQUE_NAME}

in the file "myresponsefile.rsp":

sed -i "s/initParams=/initParams=undo_tablespace=UNDOTBS1,sga_target=9GB,db_block_size=32768BYTES,control_files=\"\/u02\/oradata\/{DB_UNIQUE_NAME}\/control01.ctl\"\,\"\/recovery\/fra\/{DB_UNIQUE_NAME}\/control01.ctl\"),db_recovery_file_dest=\/u04\/recovery\/{DB_UNIQUE_NAME} /" myreponse_file.rsp

Note that all double quotes (") and forward (/) slashes must be masked by the backslash charcater \ to be interpreted correctly.

Cause and solution to ORA-00058: DB_BLOCK_SIZE must be 8192 to mount this database (not 16384)

You attempt to execute dbca silently, using a response file, as shown below:

dbca -createDatabase -responsefile mydb01.rsp -silent

But it errors out with the error:

[WARNING] ORA-00058: DB_BLOCK_SIZE must be 8192 to mount this database (not 16384)

and the instance is left running, with an unmounted database.

Cause:

This means you are using a pre-defined template for dbca that includes datafiles.

When you do this, you cannot change the db_block_size. It is set to 8K, and carved in stone.

Solution:

Create your own, customized template and refer to that instead.

Remember that templates ending with the extension .dbc contains database files, so they will be significantly faster to use, than custom made templates ending with the extension .dbt - the latter will have to go through the "CREATE DATABASE" statements from scratch.

Templates that do not contain datafiles have the extension .dbt

What you can do in order to have your cake and eat it, too, is to first create a database with a non-confirming db_block_size, then create a dbca template based on this new database, including its datafiles.

I will see if I have time to write a blog post about how to do extactly this.