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Databases Beginner

What is Foreign Key?

A column that creates a link between two tables by referencing the primary key of another table.

Foreign keys enforce referential integrity — ensuring relationships between tables remain consistent. For example, an orders table might have a customer_id foreign key referencing the customers table.

Foreign key constraints can specify behavior on delete/update: CASCADE (propagate changes), SET NULL, SET DEFAULT, or RESTRICT (prevent action). They are fundamental to relational database design.

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B-Tree Index
The default index type in most databases that organizes data in a balanced tree structure for efficient searching, sorting, and range queries.
CTE (Common Table Expression)
A temporary named result set defined within a SQL statement using the WITH clause, improving query readability and enabling recursion.
Transaction
A sequence of database operations that are treated as a single unit — either all succeed or all are rolled back.
Connection Pool
A cache of database connections that can be reused, avoiding the overhead of creating new connections for each request.
Database Index Types
Different index structures (B-tree, Hash, GIN, GiST, BRIN) optimized for various query patterns and data types.
JSONB
PostgreSQL's binary JSON data type that stores JSON documents with indexing, querying, and manipulation capabilities.
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