Articles

Elasticsearch and Opensearch

October 04, 2026
Databases Notes
EN

OpenSearch and Elasticsearch are search-oriented distributed data engines built around Apache Lucene concepts such as inverted indexes, analyzers, mappings, shards, and replicas...

Distributed Sql

October 04, 2026
Databases Notes
EN

Distributed SQL databases keep a relational SQL model while distributing data and replication across multiple nodes...

Cassandra

October 04, 2026
Databases Notes
EN

Apache Cassandra is a distributed wide-column database designed for high write throughput, horizontal scale, multi-node availability, and predictable key-oriented access...

Sql Server

October 04, 2026
Databases Notes
EN

Microsoft SQL Server is a relational database engine widely used in enterprise applications, business systems, reporting, and Microsoft-centric environments. It supports transactional workloads, analytical features, mature administration tooling, and deep integration with the .NET and Azure ecosyste...

Mongodb

October 04, 2026
Databases Notes
EN

MongoDB is a popular open-source NoSQL database management system that offers a flexible and scalable approach to data storage. Instead of using the traditional table-based relational database structure, MongoDB stores data in flexible, JSON-like documents, which means fields can vary from document ...

Mysql

October 04, 2026
Databases Notes
EN

MySQL is a popular open-source RDBMS known for its reliability, performance, and ease of use. Developed by Oracle Corporation, it powers numerous web applications, content management systems, and enterprise solutions. Its robust architecture efficiently manages large databases, making it a top choic...

Neo4J

October 04, 2026
Databases Notes
EN

Neo4j is a leading open-source graph database management system that specializes in handling data with complex and interconnected relationships. Unlike traditional relational databases that use tables and rows, Neo4j stores data in nodes and relationships, allowing for more natural and efficient mod...

Redis

October 04, 2026
Databases Notes
EN

Redis is an in-memory data store built around specialized data structures such as strings, hashes, lists, sets, sorted sets, streams, JSON, geospatial indexes, probabilistic structures, and newer vector-oriented capabilities...

Indexing Strategies

October 04, 2026
Databases Notes
EN

An index is an additional structure that helps the database find selected rows. It is comparable to a book's index: look up a topic, find its location, and then read the relevant pages. The database still has to retrieve and return the answer...

Denormalization

October 04, 2026
Databases Notes
EN

Normalization separates facts so each has a clear home. Denormalization deliberately stores an additional copy or precomputed result to make a particular read cheaper. It creates a new responsibility: keep that copy correct, or explicitly allow it to lag...

Distributed Database Systems

October 04, 2026
Databases Notes
EN

A distributed database system stores and processes logically related data across multiple machines, processes, availability zones, or geographic locations while trying to present an application with a coherent database abstraction...

Cap Theorem

October 04, 2026
Databases Notes
EN

The CAP theorem describes what happens to a distributed read/write service when parts of the system can no longer communicate...

Performance Monitoring and Tuning

October 04, 2026
Databases Notes
EN

Performance tuning should start with a measured problem...

Identity Authentication and Access Control

October 04, 2026
Databases Notes
EN

Database security starts with answering three different questions...

Sql Injection

October 04, 2026
Databases Notes
EN

SQL injection occurs when untrusted input changes the structure of a SQL statement...

Querying Nosql Databases

October 04, 2026
Databases Notes
EN

There is no universal NoSQL query language. A document database, key-value store, wide-column database, and graph database expose different query shapes because they organize data differently...

Crud in Sql vs Nosql

October 04, 2026
Databases Notes
EN

Comparing common CRUD operations in SQL (relational databases) and MongoDB (a NoSQL document store) provides valuable insights into the differences between relational and non-relational databases. Understanding these differences is crucial for developers and database administrators when designing an...

Types of Nosql Databases

October 04, 2026
Databases Notes
EN

NoSQL databases are commonly grouped by data model: key-value, document, wide-column, and graph. These categories describe how data is represented and accessed; they do not by themselves guarantee horizontal scalability, eventual consistency, low latency, or schema flexibility. Those properties depe...

Key Value Modeling

October 04, 2026
Databases Notes
EN

A key-value store exposes a simple idea...

Graph Modeling

October 04, 2026
Databases Notes
EN

Graph databases model connected data explicitly...

Wide Column Modeling

October 04, 2026
Databases Notes
EN

Wide-column databases such as Cassandra and HBase are designed around partitioned, distributed access patterns. The central modeling rule is different from a relational database...

Types of Databases

October 04, 2026
Databases Notes
EN

The first note used tables to connect customers and orders. Other databases represent data as documents, keyed values, or graph relationships. Each representation changes what is easy to read, what must be maintained during a write, and which operations need additional structures...

Databases Intro

October 04, 2026
Databases Notes
EN

A bookstore needs to remember its customers, books, orders, and remaining stock. At first, a spreadsheet or a CSV file might be enough. Once a website, a checkout desk, and an import job all change the same information, storing it becomes only part of the problem. The system also needs to answer que...

Database Management Systems Dbms

October 04, 2026
Databases Notes
EN

A database is the stored data and its definitions. A database management system (DBMS) is the software that accepts requests, checks rules, chooses execution strategies, coordinates concurrent work, and manages storage and recovery. A database driver, command-line client, and cloud hosting service s...

Data Models

October 04, 2026
Databases Notes
EN

A data model describes which facts exist, how they relate, and which rules apply. Choosing a DBMS does not automatically create that model. PostgreSQL can store an excellent design or a confused one; a MongoDB document can group a useful record or duplicate facts that are difficult to maintain...

Multi Master Replication

October 04, 2026
Databases Notes
EN

Multi-primary replication—also called multi-master or active-active replication—allows more than one database node to accept writes...

Master Standby Replication

October 04, 2026
Databases Notes
EN

Primary–standby replication is a replication topology in which one database server acts as the authoritative writer and one or more standby servers follow the primary's changes...

Intro to Replication

October 04, 2026
Databases Notes
EN

Replication keeps database data on more than one node by transferring changes from one database instance to another...

Synchronous vs Asynchronous Replication

October 04, 2026
Databases Notes
EN

The fundamental difference between synchronous and asynchronous replication is...

Spark Sql

October 04, 2026
Databases Notes
EN

Spark SQL is Apache Spark's structured-data engine. It lets you express work with SQL or DataFrame operations while Spark distributes the computation across partitions...

Data Warehousing

October 04, 2026
Databases Notes
EN

A data warehouse is an analytical system built to answer questions across large amounts of historical data. Operational databases are optimized for day-to-day application work such as creating an order, updating inventory, or authenticating a user. Warehouses are optimized for scans, joins, aggregat...

Data Pipelines Orchestration and Quality

October 04, 2026
Databases Notes
EN

A data platform is more than storage and queries. Data has to move from sources to destinations reliably, transformations must run in the correct order, failures must be retried safely, and downstream users need to know whether the resulting tables are fresh and trustworthy...

Streaming Kafka and Cdc

October 04, 2026
Databases Notes
EN

Batch systems process bounded data: "all orders from yesterday." Streaming systems process data that continues arriving: clicks, payments, sensor readings, database changes, and application events...

Data Lakes and Lakehouses

October 04, 2026
Databases Notes
EN

A data lake stores large analytical datasets as files, usually in object storage. A lakehouse keeps that open-file storage model but adds table metadata so readers and writers can treat groups of files more like database tables...

Camera Controls

October 03, 2026
Standard Of Iron
EN

The RTS camera supports nine ways to move or restore the view. The same control definitions feed the in-battle legend and field manual, while automated tests cover the underlying geometry and input rules. This page explains the complete control model and ends with the manual regression pass needed f...