[GitHub] [spark] MaxGekk commented on a change in pull request #22721: [SPARK-19784][SPARK-25403][SQL] Refresh the table even table stats is empty

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MaxGekk commented on a change in pull request #22721:
URL: https://github.com/apache/spark/pull/22721#discussion_r554586011



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File path: sql/core/src/main/scala/org/apache/spark/sql/execution/command/CommandUtils.scala
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@@ -50,6 +50,9 @@ object CommandUtils extends Logging {
       catalog.alterTableStats(table.identifier, Some(newStats))
     } else if (table.stats.nonEmpty) {
       catalog.alterTableStats(table.identifier, None)
+    } else {
+      // In other cases, we still need to invalidate the table relation cache.

Review comment:
       Could you explain why we need to refresh table while updating stats, please. For instance, we can do the same work twice. See:
   1. InsertIntoHiveTable: https://github.com/apache/spark/blob/157b72ac9fa0057d5fd6d7ed52a6c4b22ebd1dfc/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala#L113-L115
   2. LoadDataCommand : https://github.com/apache/spark/blob/ddc0d5148ac6decde160cca847b5db5d6de1be58/sql/core/src/main/scala/org/apache/spark/sql/execution/command/tables.scala#L394-L396
   3. AlterTableDropPartitionCommand: https://github.com/apache/spark/blob/e0e06c18fd479ac86963ec26ab82b0dc5536bc83/sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala#L586-L587




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