Understanding where time goes in a query during execution is of upmost importance. It is the result of the precise and restrictive formulation of the SQL statement, its compilation into a logical query plan, its subsequent morphing into a physical execution plan, and finally the execution traces themselves.
This phase of application development, and even more so during maintenance and development of the MonetDB code itself, is supported by a few SQL statement modifiers. They are part of the SQL syntax and can be used also using the JDBC/ODBC interfaces, because they return a ordinary result table.
Furthermore, the program Monetdb Stethoscope can be attached to a running database server to obtain more detailed information on the system behavior.
PLAN SQL statement, to access the logical (relational) plan.
EXPLAIN SQL statement, to access the physical plan.
TRACE SQL statement, to retrieve the execution trace.
DEBUG SQL statement, to debug the plan execution.