MVCC (Multi-Version Concurrency Control) feature allows databases to provide concurrent access to data. This allows each SQL statement to see a snapshot of data as it was some time ago, regardless of the current state of the underlying data. This prevents statements from viewing inconsistent data produced by concurrent transactions performing updates on the same…
Oracle Goldengate supports Oracle to PostgreSQL migrations by supporting PostgreSQL as a target database, though reverse migration i.e PostgreSQL to Oracle is not supported. One of the key aspect of these database migrations is initial data load phase where full tables data have to copied to the target datastore. This can be a time consuming…
In this post, we would understand what are reserved instances, when do you need them and various ways to monitor them in your environment. As more enterprises are embracing AWS cloud technologies, we need to understand AWS’s breadth of services and pricing options to right size our compute resources and run efficient infrastructure. Cost optimization…
This is quick post summarizing issues encountered while setting up ssh equivalence on EC2 instance. I was setting up RHEL7 EC2 instances and followed below procedure to setup ssh equivalence Generate rsa key-pair using ssh-keygen -t rsa on both hosts Copy the public keys to the remote server in authorized_keys file Modify file permission to…
PostgreSQL logs contains useful information which can help in troubleshooting performance issues,auditing and performing historical analysis. Some of items which can be logged are listed below Client connection and disconnection messages Failed DB connection request Database sql statement errors Database Fatal Errors Auditing Information Database Lock history Long running queries and Query plan logging High…
In this post, I will share issue faced while working with function based index in PostgreSQL . I was performing database migration from Oracle to PostgreSQL and used AWS Schema Conversion Tool(SCT) for converting the database schema.AWS Schema conversion tool takes care of automatically converting schema from one database engine to other. You can get…
This post is applicable for hosted wordpress installations where auto-updates are disabled. Yesterday, I noticed there was blog post “Hacked by Unknown” on Askdba blog. Post was written by White Hat Hacker who exploited the Content injection vulnerability in 4.7.0 and 4.7.1. This vulnerability allows any visitor (unauthorized user) to assume role to edit/create blog…
I have followed the steps in Oracle Documentation link: https://docs.oracle.com/cd/E63000_01/EMXIG/ch2_deployment.htm#EMXIG215 to configure Exadata Database Machine in OEM13c. If you want to configure your Exadata in OEM13c you have to follow the above mentioned link. In this post I will share the mandatory steps for configuration, and some of the issues which I faced while configuring the Exadata…
Before opting to procure Exadata machines, the first thing you need to check is the readiness of your data center to hold these machines. Exadata’s dimensions are similar to other normal racks i.e a 42U rack. The complete details for X5-2 physical site requirements can be found HERE. This is very important step as, for some data…
5th April 2016, Oracle announced arrival of Exadata X6-2. Overview of all its capabilities can be found HERE. Check DataSheet for list of hardware components and capacity of each X6-2 rack. Sometimes, Oracle changes hardware specifications for its racks e.g X5-2 was released with 4TB HDD initially, but after few months the datasheet was modified and…
Upgrading database hardware in an organization is always a cumbersome process. The most time consuming step is, planing for the upgrade, which mainly includes choosing right hardware for your Oracle databases. After deciding on the hardware type for your databases, rest will be taken care by technical teams involved. I will be discussing, how I…
