ExplainCommand Logical Command¶

ExplainCommand is a logical command to display logical and physical query plans (with optional details about codegen and cost statistics) that represents EXPLAIN SQL statement at execution.

Creating Instance¶

ExplainCommand takes the following to be created:

• LogicalPlan
• ExplainMode

ExplainCommand is created when:

• SparkSqlAstBuilder is requested to parse EXPLAIN statement

Output Attributes¶

ExplainCommand uses the following output attributes:

• plan (type: StringType)

Executing Command¶

run(
  sparkSession: SparkSession): Seq[Row]

run requests the given SparkSession for SessionState that is requested to execute the given LogicalPlan.

The result QueryExecution is requested to explainString with the given ExplainMode that becomes the output.

In case of a TreeNodeException, run gives the following output:

Error occurred during query planning:
[cause]