DESCRIBE
Use the DESCRIBE
command to check the information or execution fragments of a relation (table, source, sink, view, materialized view).
Syntax
Added in v2.4: DESCRIBE FRAGMENTS
.
Parameter | Description |
---|---|
relation_name | The table, source, sink, view or materialized view whose columns will be listed. |
DESCRIBE
This command shows the columns, primary key, distribution key, indexes, and description (comment) of a specified table, source, sink, view, or materialized view.
DESCRIBE <relation_name>
is similar to SHOW COLUMNS FROM <relation_name>
, but DESCRIBE
also provides information about indexes and table/column comments.
Output:
DESCRIBE FRAGMENTS
This command shows the distributed execution fragments of the job associated with the specified relation (e.g., a materialized view, table, or source). It helps in understanding the job’s physical structure, parallelism, and data flow, which is useful for debugging and optimization.
Sample Output:
The output has a similar format like EXPLAIN (DISTSQL)
, but DESCRIBE FRAGMENTS
operates on an existing job rather than a new statement being planned.
To check the runtime performance of each operator, use EXPLAIN ANALYZE
.