Explain Statement

You may use an EXPLAIN statement to obtain a query plan. This is built into the language support and is the preferred mechanism when using the pg/ODBC transport. If you are using a Teiid JDBC client, you may also use SET/SHOW statements.

Usage:

EXPLAIN [(explainOption [, ...])] statement

explainOption :=
      ANALYZE [TRUE|FALSE]
    | FORMAT {TEXT|YAML|XML}

If no options are specified the default it provide the plan in text format without executing the query.

If ANALYZE or ANALYZE TRUE is specified, then the statement will actually be executed - unless the client has already turned on the NOEXEC option. The resulting plan will include runtime node statistics from the fully executed statement - all side effects, including updates, will still occur. You may need to use a transaction to rollback any unwanted side effects.

While this is superficially the same syntax as Postgresql, the plan provided in the various formats is the same that has been provided by Teiid in prior versions.

See also Query Plans for interpreting the results.

Example

EXPLAIN (analyze) select * from really_complicated_view

Will return a text formatted plan from an actual run of the given statement.

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