[GitHub] [hudi] xiarixiaoyao commented on a diff in pull request #4910: [HUDI-2560][RFC-33] Support full Schema evolution for Spark

[GitBox <gi...@apache.org>]

xiarixiaoyao commented on code in PR #4910:
URL: https://github.com/apache/hudi/pull/4910#discussion_r1014970711


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hudi-client/hudi-client-common/src/main/java/org/apache/hudi/table/action/commit/HoodieMergeHelper.java:
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@@ -78,12 +90,41 @@ public void runMerge(HoodieTable<T, HoodieData<HoodieRecord<T>>, HoodieData<Hood
 
     BoundedInMemoryExecutor<GenericRecord, GenericRecord, Void> wrapper = null;
     HoodieFileReader<GenericRecord> reader = HoodieFileReaderFactory.getFileReader(cfgForHoodieFile, mergeHandle.getOldFilePath());
+
+    Option<InternalSchema> querySchemaOpt = SerDeHelper.fromJson(table.getConfig().getInternalSchema());
+    boolean needToReWriteRecord = false;
+    // TODO support bootstrap
+    if (querySchemaOpt.isPresent() && !baseFile.getBootstrapBaseFile().isPresent()) {
+      // check implicitly add columns, and position reorder(spark sql may change cols order)
+      InternalSchema querySchema = AvroSchemaEvolutionUtils.evolveSchemaFromNewAvroSchema(readSchema, querySchemaOpt.get(), true);

Review Comment:
   1) querySchema  is the latest table schema which parsed from commit file.   eg: a int, b string, c int
   2) readSchema is write schema(from dataFrame) by defalut, eg: a int, b string, c int, d string, e string
   we merge querySchema and readSchema to get the final schema, eg: a int, b string, c int, d string, e string
   



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