Posts tagged "query plans"

Your tenant has enough documents, but an HNSW query returns too few. Compare real plans, iterative scans, and an exact fallback without weakening access checks.

Generate a multi-row-group Parquet file, query a narrow range from Rust, and separate a pushed-down filter from measured I/O savings.

Capture actual SQL Server plans from Rust with bound parameters, then separate parameter-sensitive behavior from a slow query that only looks identical.

Without statistics, SQLite picked the wrong index and took 97 ms instead of 0.9 ms. ANALYZE fixed it. Then I changed the data, and the old statistics kept a slow plan that PRAGMA optimize did not see. Statistics are derived data too, and they can also live in an open connection.

An index exists, and the plan still says SCAN. I tested six cases on SQLite: a function on the column, LIKE, a leading wildcard, OR, a join between a TEXT and an INTEGER column, and a value that matches 93% of the rows. In the last one, ignoring the index is the right choice.