Glossary · DatabasesACID (Database Properties)ACID stands for atomicity, consistency, isolation, and durability, the four guarantees that make database transactions reliable even during errors and crashes.Glossary · DatabasesCAP TheoremThe CAP theorem states that a distributed data store facing a network partition must choose between consistency and availability.Glossary · DatabasesCRUDCRUD stands for Create, Read, Update, and Delete, the four basic operations for managing persistent data in databases and applications.Glossary · DatabasesDatabaseA database is an organized collection of data stored electronically so applications can save, search, update, and retrieve it reliably and efficiently.Glossary · DatabasesDatabase BackupA database backup is a saved copy of database data that lets you restore it after corruption, accidental deletion, hardware failure, or an attack.Glossary · DatabasesDatabase Connection PoolA connection pool keeps a set of open database connections ready for reuse, avoiding the cost of opening a new one for every request and capping server load.Glossary · DatabasesDatabase DeadlockA database deadlock happens when two transactions each hold locks the other needs, so neither can proceed until the database cancels one of them.Glossary · DatabasesDatabase IndexA database index is a separate data structure that lets the database find rows by column values quickly instead of scanning the whole table.Glossary · DatabasesDatabase MigrationA database migration is a versioned script that changes a database schema or data, letting teams apply and track changes consistently across environments.Glossary · DatabasesDatabase NormalizationDatabase normalization is the process of structuring tables to reduce redundancy and update anomalies by splitting data into related tables.Glossary · DatabasesDatabase PartitioningDatabase partitioning divides a large table into smaller parts, often by date or key range, within one server to speed queries and simplify data retention.Glossary · DatabasesDatabase ReplicationDatabase replication copies data from one database server to others in near real time, improving availability, read capacity, and disaster recovery.Glossary · DatabasesDatabase SchemaA database schema is the formal definition of a database structure, including its tables, columns, data types, keys, indexes, and constraints.Glossary · DatabasesDatabase ShardingDatabase sharding splits a large dataset across multiple servers, each holding a subset of rows, so storage and write load can scale horizontally.Glossary · DatabasesDatabase TransactionA database transaction groups several operations into one all-or-nothing unit of work, committed together on success or rolled back together on failure.Glossary · DatabasesDatabase TriggerA database trigger is code that runs automatically when a row is inserted, updated, or deleted, used for auditing, validation, and syncing derived data.Glossary · DatabasesDatabase ViewA database view is a saved query that behaves like a virtual table, simplifying complex queries and limiting what users can see.Glossary · DatabasesDBMS (Database Management System)A DBMS is the software that creates, stores, secures, and queries databases, handling storage, concurrency, transactions, and access control for applications.Glossary · DatabasesDocument DatabaseA document database stores records as self-contained JSON-like documents, letting each record hold nested data and vary in structure.Glossary · DatabasesEventual ConsistencyEventual consistency is a model where replicas may briefly return different data after a write but converge to the same value if no further updates occur.Glossary · DatabasesForeign KeyA foreign key is a column that references the primary key of another table, enforcing that related rows exist and keeping tables consistent.Glossary · DatabasesGraph DatabaseA graph database stores data as nodes and relationships, making it efficient to query highly connected data such as social networks and recommendations.Glossary · DatabasesKey-Value StoreA key-value store is a simple database that saves and retrieves each value by a unique key, offering very fast lookups and easy horizontal scaling.Glossary · DatabasesMariaDBMariaDB is an open-source relational database forked from MySQL that stays largely compatible with it while adding its own engines and features.Glossary · DatabasesMongoDBMongoDB is a popular document database that stores flexible JSON-like documents in collections and scales horizontally through replication and sharding.Glossary · DatabasesMySQLMySQL is a widely used open-source relational database management system that powers many websites, including most WordPress installations.Glossary · DatabasesN+1 Query ProblemThe N+1 query problem is a performance bug where code runs one query for a list and then one more query per item, causing hundreds of needless database calls.Glossary · DatabasesNoSQLNoSQL covers databases that use non-tabular models such as documents, key-value pairs, wide columns, or graphs, often trading rigid structure for scale.Glossary · DatabasesORM (Object-Relational Mapping)An ORM is a library that maps database tables to objects in a programming language, so code can query and save data without writing raw SQL.Glossary · DatabasesPostgreSQLPostgreSQL is an open-source object-relational database known for standards compliance, strong ACID guarantees, and rich features like JSONB and extensions.Glossary · DatabasesPrimary KeyA primary key is a column or set of columns whose values uniquely identify each row in a table, never repeating and never being null.Glossary · DatabasesQuery Execution PlanA query execution plan is the step-by-step strategy a database chooses to run a query, showing scans, index use, join methods, and estimated costs.Glossary · DatabasesQuery OptimizationQuery optimization is the process of making database queries faster and cheaper by choosing better plans, adding indexes, and rewriting inefficient SQL.Glossary · DatabasesRedisRedis is an in-memory data store used as a cache, session store, message broker, and fast key-value database with data structures like lists and sets.Glossary · DatabasesRelational DatabaseA relational database stores data in tables of rows and columns, links tables through keys, and is queried with SQL while enforcing constraints.Glossary · DatabasesSQL (Structured Query Language)SQL is the standard language for defining, querying, and modifying data in relational databases, using statements such as SELECT, INSERT, and UPDATE.Glossary · DatabasesSQL JOINA SQL JOIN combines rows from two or more tables based on a related column, letting one query return data that is stored in separate tables.Glossary · DatabasesSQLiteSQLite is a lightweight, serverless relational database stored in a single file, embedded directly into applications such as mobile apps and browsers.Glossary · DatabasesStored ProcedureA stored procedure is a named, precompiled set of SQL statements saved inside the database and run on demand, often with parameters.Glossary · DatabasesTime-Series DatabaseA time-series database is optimized for storing and querying timestamped data such as metrics, sensor readings, and logs, with fast writes.