Maximize your SQL efficiency: SELECT best practices

QuestDB is an open-source time-series database designed for high-performance workloads, emphasizing ultra-low latency and high ingestion throughput. It supports SQL and Parquet, ensuring data portability without vendor lock-in. The guide provides best practices for writing efficient SQL queries, particularly focusing on the SELECT statement, to enhance performance and reduce resource usage. Key recommendations include specifying only necessary columns to minimize data transfer, filtering queries by designated timestamps to optimize data retrieval, and aligning table partitions with typical query patterns for improved efficiency. It also advises on the strategic use of JOINs, symbols for repetitive strings, and the importance of using the EXPLAIN command to understand query execution. Additionally, it highlights the significance of applying filters early in query structures and suggests applying ORDER BY at the end of queries to improve processing time. The guide underscores the importance of staying updated with the latest database versions to leverage performance enhancements and suggests utilizing SQL extensions specific to QuestDB for further optimization.