Learning term
B-tree index — PostgreSQL
B-tree index accelerates matching search and sort operations at the cost of storage and writes. This card shows its role in “PostgreSQL” and a safe diagnostic path.
Orientation
B-tree index accelerates matching search and sort operations at the cost of storage and writes. At this level, separate purpose, input, and visible result. Place B-tree index within PostgreSQL before changing settings or files.
Practical use
Use EXPLAIN when a common query remains slow despite an index. Start in a sandbox with neutral examples. Record the expected state, make one controlled change, and compare status output, application behavior, and logs.
Technical understanding
B-tree index accelerates matching search and sort operations at the cost of storage and writes. Technically, B-tree index connects through interfaces, configuration, state, or dependencies. Trace data from input to output and check versions, permissions, networking, storage, and resources separately.
Operations and debugging
Use EXPLAIN when a common query remains slow despite an index. In production-like operations, use measurable signals, least privilege, reproducible configuration, and a documented rollback. Preserve evidence, isolate the cause, and verify the correction with the same test.
Exercise
Try it safely
Use EXPLAIN when a common query remains slow despite an index. Open an isolated test environment and run “psql --version && printf "%s\n" "SELECT 1;"”. Write down the expected output first, do not alter production data, and record one safe next diagnostic step.
psql --version && printf "%s\n" "SELECT 1;"Quick check
Can you explain the purpose, observable state, and most common failure source of B-tree index — PostgreSQL in one sentence each? Which evidence would you preserve before changing anything, and which repeated test would prove that the correction actually worked?