Slowquery

Slowquery is a term used in database management to describe a query that takes longer to execute than a defined performance threshold. It is used to identify and diagnose performance problems in both relational and non-relational systems. Slowqueries can arise at the level of individual statements or as part of heavier workload patterns.

Measurement and logging: Many databases allow configuring a time threshold; for example, a long_query_time or log_min_duration_statement setting determines when a query is recorded as slow. Logs typically include the query text, execution time, timestamp, user, and the affected schema objects. Some systems also collect per-query statistics with a profiler or performance schema.

Common causes: Missing or misused indexes, non-sargable predicates, large data volumes, complex joins, sorts, and repeated scans. Outdated statistics, parameter sniffing, inefficient execution plans, and resource contention (CPU, I/O, memory) also contribute. In NoSQL stores, slow queries can reflect inefficient scans of unindexed ranges or unoptimized data models.

Optimization: Use analysis tools such as EXPLAIN or EXPLAIN ANALYZE to inspect plans, add or adjust indexes, rewrite queries to be more selective, and consider denormalization or partitioning for large tables. In addition, adjust caching, connection pooling, and resource limits, and implement ongoing monitoring to catch regressions.

Impact and related concepts: Slowquery monitoring helps maintain responsiveness and throughput. It complements general query optimization practices and performance testing; addressing slow queries is a frequent part of database administration.