Profiling Queries

SereneDB supports profiling queries via the EXPLAIN and EXPLAIN ANALYZE statements.

EXPLAIN

To see the query plan of a query without executing it, run:

Query

EXPLAIN    SELECT count(*)    FROM generate_series(1, 100) AS t(i)    WHERE i % 2 = 0;

The output of EXPLAIN contains the estimated cardinalities for each operator.

EXPLAIN ANALYZE

To profile a query, run:

Query

EXPLAIN ANALYZE    SELECT count(*)    FROM generate_series(1, 100) AS t(i)    WHERE i % 2 = 0;

The EXPLAIN ANALYZE statement runs the query, and shows the actual cardinalities for each operator, as well as the cumulative wall-clock time spent in each operator.