spark技术分享Command Contract — Eagerly-Executed Logical Operator
Command is the marker interface for logical operators that represent non-query commands that are executed early in the query plan lifecycle (unlike logical plans in general).
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Note
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Command is executed when a Dataset is requested for the logical plan (which is after the query has been analyzed).
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Command has no output schema by default.
Command has no child logical operators (which makes it similar to leaf logical operators).
| Command | Description |
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