Query Plans

SQL Performance Tuning: Indexes, Joins, and Query Plans SQL performance tuning helps data apps feel fast. The fastest query is often the one that scans the fewest rows. A good index strategy and careful join choices let the database work with small, predictable data sets. Indexes form the foundation. Create indexes on columns that appear in WHERE, JOIN, ORDER BY, or GROUP BY clauses. Use B-tree indexes for most needs. When several columns are used together in a predicate, a composite index on (colA, colB) can be powerful, but the order matters: place the most selective column first. A covering index, which includes all columns the query reads, avoids extra lookups. But too many indexes slow writes and consume space, so choose thoughtfully. For example, if you filter by status and created_at, an index on (status, created_at) often helps dozens of similar queries. Keep in mind that update-heavy workloads may favor fewer, well-placed indexes. ...

Database Performance Tuning and Scaling Good database performance comes from understanding how data is used. Start by watching how often different queries run, where data is stored, and when traffic peaks. A small slow query can become a bottleneck as your user base grows, so set a baseline and plan for gradual improvements. Understand your workload Measure reads vs writes, hot data paths, and peak hours. Examine slow query logs and basic metrics to map hotspots. Prioritize fixes that touch the most users or the most time in the query path. Keep an eye on locking and long transactions that block other work. ...

SQL Performance Optimization: Practical Tips Fine-tuning SQL performance starts with watching what the database does, not guessing. Before changing code or server settings, measure with a realistic workload and a recent dataset. Small gains from careful indexing and query structure add up quickly. In this guide you’ll find practical steps you can apply today, with ideas that work in MySQL, PostgreSQL, or MariaDB. Start by writing clean queries and selecting only what you need. Avoid SELECT * and return only the columns you display. This reduces I/O and makes it easier for the planner to choose efficient plans. Next, invest in the right indexes. A good index supports common lookups and range queries, and a composite index can cover a whole WHERE and ORDER BY clause, letting the database read from the index instead of the table. Ensure columns used in WHERE predicates are mapped to the index, and avoid applying functions to indexed columns in the predicate, which disables usage. ...