godfreyhe commented on a change in pull request #12728:
URL: https://github.com/apache/flink/pull/12728#discussion_r444047821
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File path:
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/TableResult.java
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@@ -131,14 +131,27 @@
* it... // collect same data
* }
* }</pre>
+ *
+ * <p>This method guarantees end-to-end exactly-once record delivery
+ * which requires the checkpointing mechanism to be enabled.
+ * By default, checkpointing is disabled. To enable checkpointing,
+ * call `StreamExecutionEnvironment#enableCheckpointing()` method.
+ *
+ * <p>Only this method or {@link #print()} method can be called for a
TableResult instance,
+ * because the result can only be accessed once.
*/
CloseableIterator<Row> collect();
/**
* Print the result contents as tableau form to client console.
*
- * <p><strong>NOTE:</strong> please make sure the result data to print
should be small.
- * Because all data will be collected to local first, and then print
them to console.
+ * <p>This method guarantees end-to-end exactly-once record delivery
+ * which requires the checkpointing mechanism to be enabled.
+ * By default, checkpointing is disabled. To enable checkpointing,
+ * call `StreamExecutionEnvironment#enableCheckpointing()` method.
Review comment:
yes, it is required in streaming mode.
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