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Utility statements

ZetaSQL supports the following utility statements.

EXPLAIN

EXPLAIN query;

The EXPLAIN statement provides information on how ZetaSQL would execute a given query. This statement does not execute the query.

DESCRIBE/DESC

DESCRIBE [object_type] object [FROM source];
DESC [object_type] object [FROM source];

The DESCRIBE statement provides a description for an object, such as a table. This statement is analogous to EXPLAIN. While EXPLAIN provides information on how the query would be executed, DESCRIBE provides information about an object.

The DESC statement is the short form of DESCRIBE.

This statement includes an optional FROM syntax. This syntax can help clarify ambiguous statements that could match multiple objects.

This statement uses the following variables:

  • object_type: An optional type for the object (for example, TABLE).
  • object: Identifies the object.
  • source: Identifies the source that contains the object.

Example

The following example returns a description of a table named foo.

DESCRIBE TABLE foo;

SHOW

SHOW object_type [FROM object] [LIKE pattern];

The SHOW statement produces a list of objects, usually in a format that resembles a query result.

This statement uses the following variables:

  • object_type: An optional type for the object (for example, TABLE).
  • object: Identifies the object.
  • pattern: Provides a pattern, such as a STRING, that object names should match.