Presto 0.157.1 Documentation

8.15. EXPLAIN ANALYZE

8.15. EXPLAIN ANALYZE

Synopsis

EXPLAIN ANALYZE statement

Description

Execute the statement and show the distributed execution plan of the statement along with the cost of each operation.

Note

The stats may not be entirely accurate, especially for queries that complete quickly. Also, queries that have a Project or Filter above a TableScan are always inaccurate at this time (the cost will be attributed to a single node).

Examples

In the example below, you can see the CPU time spent in each stage, as well as the relative cost of each operator in the stage. Note that the relative cost of the operators is based on wall time, which may or may not be correlated to CPU time.

presto:sf1> EXPLAIN ANALYZE SELECT count(*), clerk FROM orders GROUP BY clerk;

                                          Query Plan
-----------------------------------------------------------------------------------------------
Fragment 1 [HASH]
    Cost: CPU 111.00us, Input 1000 (37.11kB), Output 10 (160B)
    Output layout: [clerk, $hashvalue, count]
    Output partitioning: SINGLE []
    - Aggregate(FINAL)[clerk] => [clerk:varchar, $hashvalue:bigint, count:bigint]
            Cost: 0.00%, Output 0 (0B)
            count := "count"("count_8")
        - RemoteSource[2] => [clerk:varchar, $hashvalue:bigint, count_8:bigint]
                Cost: 100.00%, Output 1000 (37.11kB)

Fragment 2 [SOURCE]
    Cost: CPU 8.38s, Input 1500000 (41.49MB), Output 4000 (148.45kB)
    Output layout: [clerk, $hashvalue, count_8]
    Output partitioning: HASH [clerk]
    - Aggregate(PARTIAL)[clerk] => [clerk:varchar, $hashvalue:bigint, count_8:bigint]
            Cost: 7.45%, Output 4000 (148.45kB)
            count_8 := "count"(*)
        - Project => [clerk:varchar, $hashvalue:bigint]
                Cost: 92.55%, Output 1500000 (41.49MB)
                $hashvalue := "combine_hash"(0, COALESCE("$operator$hash_code"("clerk"), 0))
            - TableScan[tpch:tpch:orders:sf1.0, originalConstraint = true] => [clerk:varchar]
                    Cost: unknown, Output: unknown
                    clerk := tpch:clerk

See Also

EXPLAIN