Explain statements

You can 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 can also use SET/SHOW statements. For more information about SET and SHOW statements, see the Client Developer’s Guide.

Usage

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

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

If no options are specified, by default the plan is provided in text format without executing the query.

If you specify ANALYZE or ANALYZE TRUE, then the statement is executed, unless the client has set 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 might 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.

For more information about how to interpret results, see Query plans.

Example

EXPLAIN (analyze) select * from really_complicated_view

Returns a text-formatted plan from an actual run of the given statement.

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