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Decommission a Data-Center In Cassandra

In this post, we will discuss how to decommission a Data center in Cassandra. Prerequisites to Decommission a Data Center:- Make sure no clients are still writing to any nodes in the data center. All traffic should move to other data center. Comment all cron-job/script which restart Cassandra and repairRead More

Cassandra: An Insights of G1GC log

This is the third post related to Garbage Collection in Cassandra. In this post we will discuss how to read G1GC log. I have already posted about enabling G1GC log in previous post. Minor GC Event:- Whenever a minor GC events occured, gc log prints below.  2020-03-13T16:15:03.803-0500: 18.259: [GC pauseRead More

Cassandra 3.0 or later: Enable GC logging

  This is the second post related to Garbage Collection in Cassandra. In this post we will discuss how can we enable GC logging with G1 or CMS Garbage Collector. I already discussed pros/cons of G1/CMS Garbage Collector in previous post. To enable the GC logs, and other parameters relatedRead More

Cassandra: Garbage Collector Introduction

In this blog post we will discuss about Garbage Collection with respect to Cassandra 3.0 or later. Optimizing Garbage Collection is very important in Cassandra. It can improve performance ~5 times performance and save huge money. What is Garbage Collection? Garbage collection also known as GC is an important featureRead More

Amazon Managed Cassandra Service(MCS)

  AWS Announced Amazon Managed (Apache) Cassandra Service (MCS):- AWS confirmed Amazon Managed Apache Cassandra Service (MCS) at AWS: reinvent 3rd Dec’19. Amazon Managed Cassandra Service provides high availability, scalability and Apache Cassandra compatible database service which is also server-less. AWS has many customers who asked to have managed CassandraRead More

WARN : “Mutation of xxx bytes is too large for the maximum size of xxx”

  In this blog post, we will explain the error of “Mutation of xxx bytes is too large for the maximum size of xxx”. Recently, we encountered an error(WARN) “Mutation of 17156436 bytes is too large for the maximum size of 16777216”. To understand the above error, we should know whatRead More

Upgrade Config Server to Replica Set

Upgrade Config Servers to Replica Set Only upgrade Mirrored config servers (SCCC) to CSRS if all members of the mongod config instance are at least v3.2.4. The existing config server must be in sync. To check config server is in sync or not- We shouldn’t get mongod config logs like- ERROR: configRead More

How Cassandra Reads the data?

  To Satisfy read/write request, it must achieve consistency level (whatever we define, either CL = 1, 2 or Quorum. To know more, please check consistency level). To complete the read request, Cassandra combine the request set of active MemTable and SSTables. Cassandra fetch data from multiple stages to discoverRead More

How Cassandra Writes Data?

How can we say Data has been written successfully? Cassandra writes data in 4 stages. When Application send request to write data, there is a coordinator which actually hash the data( it’s partitioner role) and create a token and then coordinator identify this token range belongs to which node and itRead More

Kill Long Running Queries

To Kill Long Running Queries:- Many people asked me how can we kill long running queries in one shot, as they have to find the long running queries one by one and then they kill, which is time taking. I’ve written this Java Script, it actually find the slow queriesRead More

Backup a Sharded Cluster

This article will help you to take sharded cluster backup. To take backup of sharded cluster, we will use mongodump from mongod running server, we can also use File System-Snapshot to capture the data. Procedure To take backup To create backups of a sharded cluster, we need to stop theRead More

Upgrade mongoDB 3.0 Shard Servers to 3.2

Fellas, This article is for those, who wants to upgrade their mongoDB servers 3.0 to 3.2. Note:- Before upgrading make sure you have taken backup of your database as well as config db. First test in Dev server then move to QA and Production. You can follow the below steps-Read More

Deploy a Sharded Cluster in MongoDB 3.0

Hello Guys, Welcome back again.. I am writing this article to deploy a shard in MongoDB 3.0, I’m assuming you have basic knowledge of mongodb stand alone & replica set server. Install mongoDB 3.0 in your Linux machine. ( I’m skipping the Installation process, you can also visit mongodb websiteRead More

Copy an Existing Collection to a New Collection

Hello Fellas, After a long time, I am writing an article again, this time I will let you know how to copy an existing collection data to a new collection, you can do this in two way. 1. Copy a collection to new collection in mongo shell First login toRead More

Limitation of MongoDB in 32 bit OS

Fellas, There are many limitations of 32 bit OS, if you want to install MongoDB on that machine. This situation has been faced by many people and later on they realise they need to upgrade their system or use MongoDB in Development/Test Environment only for that machine. Limitation of 32Read More

CRUD Operations in MongoDB

Hello All, After a long time writing this article, many people asked about CRUD operations of MongoDB. CRUD Operations- CRUD Operations stands for Creation, Reading, Update and Deletion of Database. I am giving information regarding how can we create Database, Collection (aka table in RDBMS World), insert data in collection,Read More

Profiling in MongoDB

In this tutorial, I will let you know profiling in MongoDB, why is it so important, and when should we enable profiling. Profiling in MongoDB Profiling in MongoDB plays a big role in query optimization, find the queries which is not using indexing, it help us to identify the slowRead More

Inner Join in MySQL

In this Article, I will let you know about Inner Join in MySQL. Inner Join :- Inner Join also known as Equi Join, Normal Join, it shows the only the result of two or more tables as condition satisfied. Let’s say we have two tables EMPLOYEE and DEPARTMENT Below isRead More

MySql Master Slave Replication Setup

In this article, I will let you know how to set up Master-Slave Replication in MySql. For this you should have two IPs, one for Master server and another one for Slave server. Consider we have the below two IPs for Master & Slave server. 10.10.19.20 – Master Server 10.10.19.22Read More

How To change data type in MongoDB

In this article, I will let you know how to change data type from String to Integer and vice versa. String to Integer data type conversion 1. First check is there any data in string for which you want to convert the data to Integer 64, It’s NumberLong() data typeRead More