Thursday, September 14, 2023

How to install an extension in a postgreSQL database

Are the desired extensions available in our installation?
[postgres@myserver.no ~]$ echo "SELECT * FROM pg_available_extensions;" | psql | egrep 'cube|earthdistance';
 cube               | 1.5             |                   | data type for multidimensional cubes
 earthdistance      | 1.1             |                   | calculate great-circle distances on the surface of the Earth
Yes they are.

Source : https://www.postgresql.org/docs/current/view-pg-available-extensions.html

Connect to the relevant database and create the extensions in the schema you want them:
postgres=# \connect mydb1
You are now connected to database "mydb1" as user "postgres".
mydb1=# create extension if not exists cube with schema myschema1 cascade;
CREATE EXTENSION
mydb1=# create extension if not exists earthdistance  with schema myschema1 cascade;
CREATE EXTENSION
mydb1=# exit

Check if they have indeed been installed:
[postgres@myserver.no ~]$ psql mydb01
psql (15.4)
Type "help" for help.

sit1=# \dx
                                                List of installed extensions
        Name        | Version |       Schema        |                              Description
--------------------+---------+---------------------+------------------------------------------------------------------------
 cube               | 1.5     | myschema1           | data type for multidimensional cubes
 earthdistance      | 1.1     | myschema1           | calculate great-circle distances on the surface of the Earth
 pg_qualstats       | 2.0.4   | public              | An extension collecting statistics about quals
 pg_stat_statements | 1.10    | public              | track planning and execution statistics of all SQL statements executed
 plpgsql            | 1.0     | pg_catalog          | PL/pgSQL procedural language
(5 rows)

Create extension is documented here

Solution for [WARNING] ORA-01081: cannot start already-running ORACLE - shut it down first when running dbca

I received the following error multiple times, when executing dbca like below:
dbca -createDatabase -responsefile ./cdb.rsp -silent
 2023-09-14 15:05:45.435 CEST ] Prepare for db operation
DBCA_PROGRESS : 10%
[ 2023-09-14 15:05:45.505 CEST ] Copying database files
DBCA_PROGRESS : 12%
[ 2023-09-14 15:05:47.250 CEST ] [WARNING] ORA-01081: cannot start already-running ORACLE - shut it down first

DBCA_PROGRESS : 40%
DBCA_PROGRESS : 100%
[ 2023-09-14 15:05:47.616 CEST ] [FATAL] Recovery Manager failed to restore datafiles. Refer logs for details.
DBCA_PROGRESS : 10%
DBCA_PROGRESS : 0%
At first I thought it was because I had forgotten to terminate some processes owned by oracle. And I also made sure that /etc/oratab was empty before I started.

Reason:

Turns out, there were old memory segments left behind that dbca considers a part of a running instance. Even if
ps -fu oracle
gave no processes in the list.

Solution:
su - oracle
sqlplus / as sysdba
shutdown abort
Given that you've set ORACLE_SID to the same value you used in your response file, this will properly shut down your instance, and clean up the memory segments left behind from the previous run.

Tuesday, September 12, 2023

How to delete a pluggable database with dbca using the command line

dbca -silent -deletePluggableDatabase \
-sourceDB cdb \
-pdbName pdb3 \

How to create a pluggable database with dbca using the command line

In the following code snippet, I am creating the pluggable database "pdb3" as a copy of the already existing pluggable database "pdb1":
dbca -silent -createPluggableDatabase \
-sourceDB cdb.skead.no \
-pdbName pdb3 \
-sourcePDB pdb1 \
-createPDBFrom PDB \
-pdbDatafileDestination "/dbfiles/oradata/cdb/pdb3/" \
-pdbAdminPassword mysecretpassword1 \
-sysPassword mysecretpassword2 \
-systemPassword mysecretpassword3 \
If you want to use the SEED database as source instead of an already existing database, remove the directive
-sourcePDB pdb1 \
and use this directive instead:
-createPDBFrom DEFAULT \
Source: Oracle 19c documentation

Friday, September 8, 2023

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.

    Thursday, September 7, 2023

    Syntax for switching over a container databases 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"