HelloWereld — Rajesh Nair

Welcome to HelloWereld

Rajesh Nair — Thu, 08 Oct 2026 00:00:00 GMT

Why I'm building a new home for my writing, projects, talks and experiments.

MongoDB and Kafka: Real-Time Data Streaming

Rajesh Nair — Wed, 20 Mar 2024 00:00:00 GMT

Building real-time data pipelines with MongoDB and Apache Kafka — a complete tutorial on setting up Change Streams and Kafka Connect for event-driven architectures.

Connection Time-Out Errors in MongoDB Java

Rajesh Nair — Fri, 15 Sep 2023 00:00:00 GMT

Troubleshooting connection timeout issues in MongoDB Java applications — understanding the root causes and implementing effective solutions.

Disaster Snapshot Recovery in Mongo

Rajesh Nair — Mon, 11 May 2020 00:00:00 GMT

Say for in a database maintenance activity we drop a collection by mistake, we can restore to the last state just before dropping the database using oplog file

Styling with Angular Material

Rajesh Nair — Fri, 17 Apr 2020 00:00:00 GMT

In the last blog , the dashboard.component.html has been styled by using angular material by using mat card and other similar tags.Follow the below steps to

Fake Service in Angular

Rajesh Nair — Thu, 16 Apr 2020 00:00:00 GMT

To call a fake rest api service from our angular application , we can use a fake service using angular.Follow the below steps to create a fake server hosting a

Rest Api in Angular

Rajesh Nair — Thu, 16 Apr 2020 00:00:00 GMT

To call a rest api service in angular, follow the below steps after setting up a fake service and routings as mentioned in previous blogs: 1. Generate an

Bootstrap in Angular

Rajesh Nair — Fri, 10 Apr 2020 00:00:00 GMT

To implement bootstrap in an angular application after creating it with ng new command , follow the below steps: 1. Open command prompt and cd to the project

Routing in Angular

Rajesh Nair — Fri, 10 Apr 2020 00:00:00 GMT

We can route hyperlinks to route to any of the components based on url changes using single page application at client side instead of loading whole page.So

Angular Overview

Rajesh Nair — Thu, 09 Apr 2020 00:00:00 GMT

Angular JS components are a below:

Angular Project Setup

Rajesh Nair — Fri, 03 Apr 2020 00:00:00 GMT

The below steps will help to setup a new project in angular js to develop an angular js based project. 1. Check if your system has already node js by using

Shell Script - Progress lk info

Rajesh Nair — Mon, 30 Mar 2020 00:00:00 GMT

Script : Progress database lk file information Script Name: lkinfo.sh Script Function: Information about the database status from lk file Script Usage:

Shell Script - Database Stop

Rajesh Nair — Thu, 26 Mar 2020 00:00:00 GMT

Script : Progress Database Stop Script Name: stoppro.sh Script Function: To stop the database instance and optionally truncate bi (-t) Script Usage:

Shell Script - Progress Add Extents

Rajesh Nair — Thu, 26 Mar 2020 00:00:00 GMT

Script : Progress add new extents Script Name: addextent.sh Script Function: Add new extent to the database provided in the add.st file in database path after

Shell Script - Progress Start Database

Rajesh Nair — Thu, 26 Mar 2020 00:00:00 GMT

Script : Progress start a database instance Script Name: startpro.sh Script Function: Start a database instance of progress with a pf file. Script Usage:

Shell Script - Progress Vairable Extent Size

Rajesh Nair — Thu, 26 Mar 2020 00:00:00 GMT

Script : Progress check Variable Extent Size Script Name: checkextent.sh Script Function: check the size of the variable extents (< $extentMaxSize set in the

Shell Script - Progress Disconnect User

Rajesh Nair — Wed, 25 Mar 2020 00:00:00 GMT

Script : Disconnect user from database Script Name: disconnect.sh Script Function: Disconnect users from databases using "proshut" Required Files: 1.

Shell Script - Progress Log Parsing

Rajesh Nair — Wed, 25 Mar 2020 00:00:00 GMT

Script : Shell script to parse the progress database log file Script Name: dblogparse.sh Script Function: Script classifies the messages into 4 categories

Shell Script - Server Statistics

Rajesh Nair — Wed, 25 Mar 2020 00:00:00 GMT

Script : Shell script to test the throughput of disk subsystem. Script Name: serverstat.sh Script Function: Statistics about server status,disk and memory

Shell Script - Bulk Renaming Files

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Bulk-Renaming Files Script Name: bulkrename.sh Script Function: It takes two arguments for the text to match and replace, and a list of arguments

Shell Script - Check Area Utilization

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Progress database area utilization Script Name: progressarearpt.sh Script Function: Get the Actual DB Size,get Max area size & current utilization per

Shell Script - Contents of Directories

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Displaying the Contents of Directories Script Name: formatdir.sh Script Function: It generates a multi column listing of files and directories,

Shell Script - File Details

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Displaying a File with Additional Information Script Name: showfile.sh Script Function:Script as an alternative to cat displaying a files additional

Shell Script - Interactive Calculator

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Interactive Calculator Script Name: calculator.sh Script Function:Script to run a fully interactive command line–based calculator. Script Usage:

Shell Script - Progress Backup

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Progress database backup Script Name: progressbackup.sh Script Function: Perform a coldhot backup for a given database. Script Usage:

Shell Script - ProgressDB Storage Growth

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Progress database Storage area size growth Script Name: progressgrowthrpt.sh Script Function:Calculate report of time remaining for extents to grow

Shell Script - Reminder Utility

Rajesh Nair — Tue, 24 Mar 2020 00:00:00 GMT

Script : Reminder Utility Script Name: remember.sh, remindme.sh Script Function: The first script, remember , lets you easily save your snippets of information

Basic Commands

Rajesh Nair — Fri, 21 Feb 2020 00:00:00 GMT

Below are the most commonly used linux commands and its purpose: && — and — or apropos — returns all documentation containing the defined command bzip/bunzip —

Linux Installation

Rajesh Nair — Fri, 21 Feb 2020 00:00:00 GMT

To install linux follow the below steps: To start the installation from DVD/CD set the BIOS to boot from CDROM. This installation guide is to install Linux

Linux Environment

Rajesh Nair — Wed, 19 Feb 2020 00:00:00 GMT

Gnome and the Bash shell are two of the most used interfaces in Linux for managing the system. GNOME (GNU Network Object Model Environment, pronounced

Linux Shells

Rajesh Nair — Wed, 19 Feb 2020 00:00:00 GMT

Using the Bourne Again Shell The Bourne Again Shell is usually just referred to as a Bash shell. It basically allows to enter Linux commands. In the Gnome

AWS Introduction

Rajesh Nair — Fri, 04 Oct 2019 00:00:00 GMT

Essential Characteristics: • On Demand Self-Service • Broad network access • Resource Pooling • Rapid Elasticity • Measured Service Deployment Model • Private

MySQL Security

Rajesh Nair — Fri, 12 Jul 2019 00:00:00 GMT

Security for a database could be at a physical level,network level,OS level,File System level or at User account level.The mysql.user table contains account

Command Line Clients

Rajesh Nair — Tue, 09 Jul 2019 00:00:00 GMT

Command Line tool benefits Quick Specific Low overhead Scriptable Schedulable Combinable General Syntax: command --opt1 --opt2=value[target] Names usually

MySQL Configuration & Setup

Rajesh Nair — Mon, 08 Jul 2019 00:00:00 GMT

This blog will cover the various configuration and setups that can be performed over a mysql server for its operations. Server command line options We can

MySQL Installation

Rajesh Nair — Mon, 08 Jul 2019 00:00:00 GMT

What is Installed bin directory ( and sbin in some ) = contains server prgms (mysqld and others) data directory( contains db directory ) innoDB tablespace file

MySQL Server

Rajesh Nair — Fri, 05 Jul 2019 00:00:00 GMT

MySQL Server has different types of distribution starting from the Original MySQL from Oracle who are the current owners of MySQL.In 2010 Oracle had merged

MySQL Resource Usage

Rajesh Nair — Thu, 04 Jul 2019 00:00:00 GMT

Global Memory Global buffers and caches are allocated on startup of mysqld and shared by all sessions.These can be general or storage engine specific.These are

MySQL Architecture

Rajesh Nair — Tue, 02 Jul 2019 00:00:00 GMT

MySQL follows a client server architecture where the mysqld programs which are the core programs of the database system act as the server and various agent

OpenEdge Interview Questions

Rajesh Nair — Wed, 15 May 2019 00:00:00 GMT

Progress Interview Questions: 1. Which version of progress you have worked on ? diff and Features 2. How you are monitoring your database? 3. Have u installed

GridFS in Mongo

Rajesh Nair — Tue, 30 Apr 2019 00:00:00 GMT

GridFS in mongo can be used to store and retrieve huge files of type image,videos,audios etc in the mongo database in the form of collection by considering the

Introduction to Unix/Linux

Rajesh Nair — Tue, 30 Apr 2019 00:00:00 GMT

How does the Linux OS work? Linux has a KERNEL and one or more SHELLS The shell is the command line interface through which the user interacts with the OS

Ops Manager in Mongo

Rajesh Nair — Wed, 17 Apr 2019 00:00:00 GMT

Ops Manager is a monitoring and administering web based tool provided by Mongo which would provide a single click provisioning for scaling,upgrades and

Security in Mongo

Rajesh Nair — Tue, 09 Apr 2019 00:00:00 GMT

Below table would give in various security features provided by Mongo:

JS Script for Shard Setup in Mongo

Rajesh Nair — Fri, 29 Mar 2019 00:00:00 GMT

Instead of setting up each shard replica set and adding them to shard in the mongos shell we can use the below js script and load it to mongos to add mongo

Sharding in Mongo

Rajesh Nair — Fri, 29 Mar 2019 00:00:00 GMT

Sharding is the method of data distribution in a mongo database environment where the data can be partitioned into different servers on the basis of "shard

Sharding Setup in Mongo

Rajesh Nair — Fri, 29 Mar 2019 00:00:00 GMT

To setup mongo sharding environment we should be ideally having the below setups A Config Databases Replica Set of 3 or more members Multiple Shard Database

Arbiters,Oplog,Write Concern in Mongo Replication

Rajesh Nair — Tue, 26 Mar 2019 00:00:00 GMT

Read Preference a.k.a “slaveOk”. In shell - rs.slaveOk() In driver – read preference Secondary can have potentially stale data due to lag in write from primary

Mongo Replication

Rajesh Nair — Mon, 25 Mar 2019 00:00:00 GMT

Replication in any database is critical for setting up a secondary instance for the database instance.In mongo replication serves the purpose of : HA - High

Mongo Replication Setup

Rajesh Nair — Mon, 25 Mar 2019 00:00:00 GMT

For a statement based replication oplog file is used to apply all the transaction on the primary node to the secondary node.The default value for oplog

Profiler in Mongo

Rajesh Nair — Sun, 24 Mar 2019 00:00:00 GMT

Profiler can be used to setup logging on the mongo instance. Events captured by the profiler: CRUD Administrative Operations Configuration Operations

Explain Plan in Mongo

Rajesh Nair — Fri, 22 Mar 2019 00:00:00 GMT

Explain plan can be used on a collection to get an explainable object. db.test1.explain().find({name:"hello"}).sort({empid:1}) { "queryPlanner" : {

Web Service Setup in Progress

Rajesh Nair — Fri, 22 Mar 2019 00:00:00 GMT

Following are the steps to follow to setup web service in a progress environment: 1. First we would require a tomcat to deploy web service application, so copy

MMAPv1

Rajesh Nair — Thu, 21 Mar 2019 00:00:00 GMT

Storage Engine determines data file format & format of indexes and are key to performance for the mongo database.It is the middletier between the database and

Mongo Indexes

Rajesh Nair — Thu, 21 Mar 2019 00:00:00 GMT

Index in a database is what bookmark is to a book, it helps the fast traversal and retrieval of documents through indexing of each document of a collection.

Wired Tiger in Mongo

Rajesh Nair — Thu, 21 Mar 2019 00:00:00 GMT

Wired tiger is a pluggable storage engine with following features: Document level locking Compression Fulfills some pitfalls of MMAPv1 Performance gain We can

Administrative Commands in Mongo

Rajesh Nair — Wed, 20 Mar 2019 00:00:00 GMT

The following are some of the commands that can be used for database administration for mongo. 1. getLastError db.getLastError() E11000 duplicate key error

Mongo Installation on RHEL VM

Rajesh Nair — Wed, 20 Mar 2019 00:00:00 GMT

To install mongo on a red hat VM , download the rpm files from mongo website according to the RHEL version you are using and the mongo version you want:

CRUD in Mongo

Rajesh Nair — Tue, 19 Mar 2019 00:00:00 GMT

CRUD corresponds to Create,Read,Update and Delete.Like any other database technology, mongo also supports CRUD operations on it by the use of its various

Mongo Basic Queries

Rajesh Nair — Mon, 18 Mar 2019 00:00:00 GMT

Mongo database supports a data driven style of deceleration in the form of JSON and BSON.To run the various queries in mongo , first start the mongo database

Mongo Operators

Rajesh Nair — Mon, 18 Mar 2019 00:00:00 GMT

Mongo database provides various operators to support the querying on the mongo shell. These are some of the operators used: Querying : 1. $gte,$gt,$lte,$lt

Starting Multiple Instances in MySQL

Rajesh Nair — Sat, 16 Mar 2019 00:00:00 GMT

We can start multiple MySQL instance in the same server by running them in different ports. To configure multiple instances, 1. add the below entries in

Galera Replication

Rajesh Nair — Fri, 15 Mar 2019 00:00:00 GMT

Galera replication is a third party open source replication utility for MySQL.Follow the below steps for setting up galera replication on all the three nodes

Group Multi Master Replication

Rajesh Nair — Thu, 14 Mar 2019 00:00:00 GMT

Group multi master replication is a master-master replication setup in MySQL. Follow the below steps to configure group multi replication: 1.Considering 3

Point in Time Recovery in MySQL

Rajesh Nair — Wed, 13 Mar 2019 00:00:00 GMT

Point in Time recovery is the recovery mechanism where we can recover a lost transaction back to our MySQL server.The transaction here might be a database or a

Resetting root password for MySQL

Rajesh Nair — Wed, 13 Mar 2019 00:00:00 GMT

In MySQL administration ,root access is critical to perform various administration tasks on the database. By any chance if the root password is lost or

Tablespace in MySQL

Rajesh Nair — Wed, 13 Mar 2019 00:00:00 GMT

In MySQL table space can be created to store tables of the MySQL server. If we don't create a tablespace of our own the default tablespace for any new table

Introduction to Mongo

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

Mongo database is an open source , high performing , schema - free, non relational and document oriented database which provides highest level of availability

Introduction to MySQL

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

MySQL is an open-source relational database management system that works on many platforms. It provides multi-user access to support many storage engines and

JSON & BSON

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

JavaScript Object Notation (JSON) is an open, human and machine-readable standard that facilitates data interchange, and along with XML is the main format for

Mongo Import & Cursors

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

Mongo database supports data to be imported to the database in the form of csv,tsv and json file formats.Below command can be used to import the file

NDB Cluster

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

NDB Cluster or Next DB Cluster in MySQL is cluster management in MySQL where multiple data nodes with multiple servers can be configured for setting up

Starting Database in Mongo

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

To start the mongo database server on the linux machine with specific parameters for the database to start with we can use a config file , generally named as

Storage Engines in MySQL

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

MySQL supports various storage engines to service the database server and perform the database activities. Each storage engine is unique and provides a

Unix Installation

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

In unix system installation can be done in more than one ways.For installing mongo in unix/linux systems follow the below steps using apt-get command use the

Windows Installation

Rajesh Nair — Tue, 12 Mar 2019 00:00:00 GMT

For installing Mongo DB in windows server follow the below steps : 1. download the latest version of mongo from the mongo db website

Replication

Rajesh Nair — Fri, 08 Mar 2019 00:00:00 GMT

Follow the below steps to configure MySQL Replication in the Linux servers : 1. For VM systems firewall has to be disabled to enable replication connections

Basic Prompt Commands

Rajesh Nair — Thu, 07 Mar 2019 00:00:00 GMT

To login to a particular database use the below command: mysql -u root -p

Basic Queries in MySQL

Rajesh Nair — Thu, 07 Mar 2019 00:00:00 GMT

After installing MySQL-Workbench , in the workbench or by opening mysql prompt in terminal use the below queries for different operations on the database 1. To

Dump and Restore

Rajesh Nair — Thu, 07 Mar 2019 00:00:00 GMT

The logical dump of all database can be done using mysqldump utility as below: mysqldump -u root -p --all-databases alldatabases.sql The logical dump of a

GUI Clients

Rajesh Nair — Thu, 07 Mar 2019 00:00:00 GMT

There are very GUI clients are present in market to manage and administer the MySQL databases.These are DBA control consoles which provide easy access to

MySQL Percona

Rajesh Nair — Thu, 07 Mar 2019 00:00:00 GMT

Percona is a third party tool used for taking physical backup of the entire MySQL Server to a backup path. Installation of Percona 1. Download the percona rpm

Openedge Replication Monitoring Status

Rajesh Nair — Tue, 11 Dec 2018 00:00:00 GMT

When "dsrutil dbname -C status" is used, the "Status" codes are returned When "dsrutil dbname -C status -detail " is used, the "Detail Status" codes are

Progress 4GL Development Basics

Rajesh Nair — Tue, 11 Dec 2018 00:00:00 GMT

ABL (Advanced Business Language). Earlier known as Progress 4GL. Even if you are a progress database administrator, having knowledge of progress 4GL language

OpenEdge Management(OEM) or Management Console/OpenEdge Explorer

Rajesh Nair — Mon, 06 Aug 2018 00:00:00 GMT

In windows version of progress openedge, the product package comes with an extra product which is not available in unix version of the openedge products -

Setting up a Database to Monitor in OEM

Rajesh Nair — Mon, 06 Aug 2018 00:00:00 GMT

After doing initial configuration and setup , a OEM dashboard on login will look like as below showing the admin server and the various resources under the

User Management in Openedge Database

Rajesh Nair — Mon, 06 Aug 2018 00:00:00 GMT

The user management of a progress Openedge database refers to the user creation on the database with adequate privileges intended for the particular user.In

OpenEdge Installation Windows

Rajesh Nair — Mon, 14 May 2018 00:00:00 GMT

Prerequisites: DBA to make sure Java already installed and we have progress Setup downloaded in the server with serial number and control numbers, and

Basic Unix commands for Progress DBA