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Query is picking a bad execution plan , fix it using Oracle baselines ?

The goal of SQL plan baselines is to preserve the performance of corresponding SQL statements, regardless of changes in the database. Examples of changes...
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LOG MINER in Oracle

Oracle LogMiner, a component of Oracle Database, provides a SQL interface for querying both live and archived redo log files. The history of activity on...
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Manual creation of SQL Profiles in Oracle Database

SQL Profiles are a powerful tool to improve performance of SQL queries in your Oracle Database. A SQL profile is a database object that contains auxiliary statistics...
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Resizing redo logs and standby Redologs in Dataguard

IN PRIMARY DATABASE :- 1) Check Instance details :- select status,instance_name,database_role from v$database,v$instance; ------------------------------------------------------------------------------------------------------------------------------------ 2) Check redo log and standby redo log size in Primary and standby :- Redo...
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Crontab : Blocking session

Blocking sessions in Oracle are sessions which holds an exclusive lock on an object and doesn’t release it before another sessions wants to update...

How To Run SQL Tuning Advisor

When we run SQL tuning advisor against a SQL statement or sql_id, it provides tuning recommendations that can be used to improve performance. It might give suggestion to...
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MEB Backup & Restore in MySQL

MySQL Enterprise Backup provides enterprise-grade backup and recovery for MySQL. It delivers hot, online, non-blocking backups on multiple platforms including Linux, Windows, Mac &...
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ORA-04021: timeout occurred while waiting to lock object while dropping Materialized View.

A materialized view, or snapshot as they were previously known, is a table segment whose contents are periodically refreshed based on a query, either...
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Unable to generate Listener Log in Prod RAC DB

Cause: Looks like ADR is having the issue. Solution: Added the below parameter in the both the nodes and restarted the listener DIAG_ADR_ENABLE_LISTENER=OFF There are 3 parameters...
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Moving datafile from one location to another in Standby

$ ps -ef|grep pmon oracle 2113 1 0 Sep20 ? ...

ORA-16047: DGID mismatch between destination setting and target database

Issue : ORA-16047: DGID mismatch between destination setting and target database alert.log alter database register logfile '/opt/data/oracle3/prod101/FRA/prod101/archivelog/2019_12_01/o1_mf_1_190698_gy5z61jw_.arc' There are 1 logfiles specified. ALTER DATABASE REGISTER LOGFILE Completed: alter...
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Apache Cassandra Performance Tuning

What is Apache Cassandra? ▪ NoSQL database ▪ Schema-free ▪ Very fast ‘write’ ▪ Cassandra is designed to handle big data workloads across multiple nodes with no single...
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Cassandra import & export

Cassandra.csv file data: car_make,car_model,start_year,id,first_name,last_name,department BMW,Saloon,2011,1,Johny,Depp,IT AUDI,Saloon,2013,2,Meryl,Streep,HR LEXUS,Sports,2011,3,Brad,Pitt,IT AUDI,Sports,2012,4,Tom,Hanks,FI BMW,Compact,2012,5,Angelina,Jolie,FI BMW,Saloon,2011,6,Tom,Cruise,HR AUDI,Compact,2013,7,Scarlett,Johansson,IT LEXUS,Compact,2013,8,Matt,Damon,IT NISSAN,Saloon,2013,9,Julia,Roberts,FI BMW,Saloon,2011,10,Nicole,Kidman,HR NISSAN,Compact,2012,11,George,Clooney,HR AUDI,Saloon,2012,12,Dwayne,Johnson,IT AUDI,Sports,2011,13,Natalie,Portman,FI Create keyspace and create tables and then importing the data form local system to Cassandra: $./bin/nodetool status $./cqlsh Cqlsh>CREATE KEYSPACE test_keyspace WITH replication =...

Protected: Cassandra Data Modelling

Why Database Modelling? Database model and it’s methodologies Database Modelling Different types of Data Models Database Modelling Steps Benefits of Data Modelling RDBMS and Cassandra Data ModeL Cassandra Data Model Data Modelling...
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Linux Administration.

A Linux distribution is a collection of (usually open source) software on top of a Linux kernel. A distribution (or short, distro) can bundle...


/etc/hosts localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 mysql-prim.localdomain mysql-prim mysql-dr.localdomain ...
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Undo Tablespace

There are two types of Undo Modes in 12.2 1) Shared Undo - The Undo tablespace is common, it is shared among the entire CDB....
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Renaming and Relocating Datafiles Online

Relocating an Online Data File SQL> ALTER DATABASE MOVE DATAFILE '/rman_backup/backup/datafile1' TO '+DATA'; Database altered. Copying an Online Data File This example copies the data file to ...
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Oracle Managed Files 11g & 12c

11g When OMF is enabled and If a datafile location is incorrect the file gets created in dbs location SQL> show parameter db_create_file_dest NAME ...
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Managing Tablespace in CDB and PDB

Managing tablespace in container database is similar to non-container database. Provided you are logged in as a privileged user and point to right container. Manage...
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Common user password change:

Common user password we can change from only cdb level .container class is optional. CDB container: ==================================== SQL> show con_name CON_NAME ------------------------------ CDB$ROOT SQL> SQL> alter user C##USERTEST identified by test container=all; User...
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Oracle-maintained users password change

From oracle 12c onwards the default user’s account passwords have to change from cdb container. container class is optional.  sys user password change ======================= CDB level using...
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Lockdown Profile: 

From 12c onwards we have new feature called lockdown profile to control the PDB level activities. It can be created in CDB container.  SQL> show...
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Common Roles Vs Local Roles

Privilege Management: Privilege management has been classified into 2 sub divisions. They are: 1) Grants 2) Roles Roles: Collection of privileges called role. In 12c we have 2 different...
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Common Grant Vs Local Grant

Privilege Management: Privilege management has been classified into 2 sub divisions. They are: 1) Grants 2) Roles Grants: oracle12c have two variant of grants. They are: 1) Common grants 2) Local...