Articles

Sql Injection

October 31, 2026
Databases Notes
EN

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

Database Migration

October 31, 2026
Databases Notes
EN

Database migration is the process of transferring data, schema, and database objects from one database environment to another. This complex undertaking is crucial when organizations aim to upgrade technology, shift infrastructures, enhance performance, or reduce costs. A successful database migratio...

Querying Nosql Databases

October 31, 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...

Document Modeling

October 31, 2026
Databases Notes
EN

A document database stores records as documents rather than normalized rows spread across many tables. The main modeling question is not "can this be JSON?" but...

Operating Nosql and Polyglot Persistence

October 31, 2026
Databases Notes
EN

NoSQL systems are often introduced through data models, but production success depends just as much on operations. A database choice adds responsibilities for deployment, backups, monitoring, security, capacity, failure recovery, schema evolution, and synchronization with other systems...

Crud in Sql vs Nosql

October 31, 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 31, 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 31, 2026
Databases Notes
EN

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

Graph Modeling

October 31, 2026
Databases Notes
EN

Graph databases model connected data explicitly...

Consistency Transactions and Replication

October 31, 2026
Databases Notes
EN

Choosing a NoSQL data model does not automatically choose a consistency model. Document, key-value, wide-column, and graph describe how data is represented. Replication, transaction scope, and read/write guarantees are separate design choices...

Nosql Databases Intro

October 31, 2026
Databases Notes
EN

NoSQL is an umbrella label for databases built around models such as documents, key-value pairs, wide-column records, and graphs. It is not one query language or one set of guarantees. Some products support transactions, joins, validation, or SQL-like queries; others expose different operations...

Wide Column Modeling

October 31, 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 31, 2026
Databases Notes
EN

The first note connected customers and orders through relational keys. Other systems organize access around nested documents, exact keys, partitions, graph edges, or analytical columns. These are model and workload choices, not a ranking of modernity or scalability. Compare a concrete read and its u...

Databases Intro

October 31, 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...

Glossary

October 31, 2026
Databases Notes
EN

Use this as a lookup reference, not a lesson to memorize linearly. Start with data and keys, then SQL, transactions, storage, distribution, and analytics. A term describes a specific role: a key, constraint, index, and join are not interchangeable simply because all four appear in one query...

Database Management Systems Dbms

October 31, 2026
Databases Notes
EN

A database is stored data plus its definitions; a DBMS is the engine responsible for interpreting requests, enforcing declared rules, executing queries, coordinating concurrent work, and recovering state. Drivers, clients, hosting, and storage services surround that engine, but do not replace its gu...

Data Models

October 31, 2026
Databases Notes
EN

A data model specifies facts, identity, relationships, and invariants before those decisions become SQL tables, documents, or graph edges. A DBMS cannot infer a good model from product choice alone: the same bookstore can be modeled well or poorly in PostgreSQL, MongoDB, or another engine. Start wit...

Spark Sql

October 31, 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 31, 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 31, 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 31, 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...

Hadoop and Hdfs

October 31, 2026
Databases Notes
EN

Hadoop is an ecosystem for storing and processing data across many machines. Its original core components solve different problems...

Data Lakes and Lakehouses

October 31, 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...

Sharding

October 30, 2026
Databases Notes
EN

Sharding distributes horizontally partitioned rows across separate nodes or clusters. A routing layer decides which shard owns a key; replication separately determines how many copies exist. Sharding can add storage or write capacity, but it also makes cross-shard reads, uniqueness rules, transactio...

Partitioning

October 30, 2026
Databases Notes
EN

Partitioning splits one logical table into smaller physical pieces according to a declared key. Partition pruning can reduce query work when the filter identifies relevant pieces; it is not automatic for every query and does not replace suitable indexes. Partition management can also make retention ...

Cap Theorem

October 30, 2026
Databases Notes
EN

CAP constrains a distributed read/write service during network partitions. When a request reaches a live node that cannot communicate with another portion of the system, maintaining a single linearizable history can require refusing or delaying some operations. This chapter develops the information ...

Eventual Consistency

October 30, 2026
Databases Notes
EN

Eventual consistency is a convergence guarantee: if updates stop and replicas can communicate and repair their states, they eventually agree on the value selected by the system's reconciliation policy. It does not promise a maximum delay, a read-your-writes experience, or preservation of every concu...

Consistent Hashing

October 30, 2026
Databases Notes
EN

Imagine you're organizing books in a vast library with shelves arranged in a circle. Each book’s position is chosen by the first letter of its title, looping back to the beginning after Z. When you install a new shelf or remove one, you’d prefer not to reshuffle every book—only a small, predictable ...

Partitioning vs Sharding

October 30, 2026
Databases Notes
EN

Partitioning divides a logical dataset into pieces. Sharding places horizontal pieces on separate nodes or clusters and introduces distributed routing and coordination. They are not mutually exclusive terms: a sharded system may also use date partitions inside each shard. The operational boundary—on...

Iron Sepulcher

October 28, 2026
Standard Of Iron
EN

The Iron Sepulcher is Standard of Iron's undead faction. It has no economy, recruitment loop, or player-selectable slot. Undead troops reach the battlefield through undead zones authored on the map: dormant sites that awaken, raise a garrison, and turn part of the terrain into a temporary strategic ...

Integration with Other Tools

October 28, 2026
Vtk Examples
EN

Integration of VTK with a variety of tools and libraries provides flexibility and power that can significantly broaden the scope of visualization projects. These integrations allow you to combine VTK’s 3D rendering capabilities with platforms that excel at data analysis, computational processing, an...

Searching Filtering and Sorting

October 26, 2026
Numpy Tutorials
EN

A search may need values, coordinates, or an ordering. These are different outputs. Decide which one you need before choosing where, nonzero, argsort, or searchsorted...

Combining Arrays

October 26, 2026
Numpy Tutorials
EN

Joining arrays is a modeling choice. Does the new data add observations, add features to existing observations, or add a new experiment axis? Those choices call for different shapes, even when all inputs contain the same number of elements...

Reshaping Arrays

October 26, 2026
Numpy Tutorials
EN

Reshaping preserves the number of elements...

Linear Equations

October 26, 2026
Numpy Tutorials
EN

For A ∈ ℝ^(m×n), x ∈ ℝⁿ, and b ∈ ℝ^m...