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Databases Intermediate

What is Query Optimization?

The process of improving database query performance through indexing, query rewriting, and schema design techniques.

Query optimization starts with EXPLAIN ANALYZE to understand execution plans. Common optimizations include adding indexes on frequently filtered/joined columns, rewriting subqueries as JOINs, avoiding SELECT *, and using LIMIT for pagination.

Advanced techniques include partial indexes (index subset of rows), covering indexes (include all needed columns), materialized views (pre-computed results), query caching, and connection pooling. Regular ANALYZE ensures the query planner has current statistics.

Related Terms

Window Function
An SQL function that performs calculations across a set of rows related to the current row without collapsing the result set.
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.
MVCC (Multi-Version Concurrency Control)
A technique where the database maintains multiple versions of data to allow concurrent reads and writes without locking.
Schema
The structure definition of a database including tables, columns, data types, relationships, indexes, and constraints.
Time-Series Database
A database optimized for storing and querying timestamped data points like metrics, sensor readings, and event logs.
Soft Delete
A pattern where records are marked as deleted with a flag or timestamp rather than being physically removed from the database.
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