SQLite Optimizes BETWEEN, OR, LIKE, & GLOB Queries
Why this is here: The article details how SQLite converts the BETWEEN clause into two separate conditions—age >= 18 AND age <= 30—allowing the optimizer to potentially use an index for range scans.
SQLite optimizes several common query operators including BETWEEN, OR, LIKE, and GLOB to improve performance. The BETWEEN clause is rewritten internally as two conditions involving greater than or equal to and less than or equal to comparisons. OR conditions, when applied to the same column, are transformed into IN clauses allowing for index usage.
When OR conditions involve different columns, SQLite evaluates each term separately and combines the results. LIKE and GLOB pattern matching can utilize indexes if the left-hand side is an indexed text column and the pattern doesn’t start with a wildcard. These optimizations depend on factors like case sensitivity and collation settings.
SQLite applies specific rules regarding ESCAPE clauses and built-in functions to ensure index compatibility. The next article in the series will cover join table ordering and its impact on query performance.