Databases Intermediate

What is Index?

A data structure that improves the speed of data retrieval operations on database tables at the cost of additional storage.

Indexes work like a book index — they allow the database to find rows without scanning the entire table. Without an index, a query on a million-row table checks every row. With an index, it jumps directly to matching rows.

Types include B-tree (default, good for ranges), hash (exact matches), GIN (full-text search), and GiST (geometric data). Over-indexing slows down writes since indexes must be updated on every INSERT/UPDATE.

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An open-source, in-memory data store used as a database, cache, message broker, and queue with sub-millisecond response times.

Time-Series Database

A database optimized for storing and querying timestamped data points like metrics, sensor readings, and event logs.

A pattern where records are marked as deleted with a flag or timestamp rather than being physically removed from the database.

A database operation that inserts a new row if it does not exist, or updates the existing row if it does.

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A technique where the database maintains multiple versions of data to allow concurrent reads and writes without locking.

The process of copying and maintaining database data across multiple servers for redundancy, failover, and read scaling.

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