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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

SQL
Structured Query Language — the standard language for managing and querying data in relational databases.
Crosstab Query
A query that transforms rows into columns, creating a pivot table view of aggregated data.
Connection Pool
A cache of database connections that can be reused, avoiding the overhead of creating new connections for each request.
ETL (Extract, Transform, Load)
A data pipeline process that extracts data from sources, transforms it into a suitable format, and loads it into a destination system.
Elastic Search
A distributed search and analytics engine built on Apache Lucene, optimized for full-text search and log analysis.
EXPLAIN ANALYZE
A PostgreSQL command that shows the execution plan of a query along with actual runtime statistics for performance tuning.
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