nbalajee commented on a change in pull request #2309:
URL: https://github.com/apache/hudi/pull/2309#discussion_r547467339
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File path: hudi-common/src/main/java/org/apache/hudi/avro/HoodieAvroUtils.java
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@@ -308,17 +309,79 @@ public static GenericRecord
rewriteRecordWithOnlyNewSchemaFields(GenericRecord r
return rewrite(record, new LinkedHashSet<>(newSchema.getFields()),
newSchema);
}
+ private static void setDefaultVal(GenericRecord newRecord, Schema.Field f) {
+ if (f.defaultVal() instanceof JsonProperties.Null) {
+ newRecord.put(f.name(), null);
+ } else {
+ newRecord.put(f.name(), f.defaultVal());
+ }
+ }
+
+ /*
+ * OldRecord: NewRecord:
+ * field1 : String field1 : String
+ * field2 : record field2 : record
+ * field_21 : string field_21 : string
+ * field_22 : Integer field_22 : Integer
+ * field3: Integer field_23 : String
+ * field_24 : Integer
+ * field3: Integer
+ *
+ * When a nested record has changed/evolved, newRecord.put(field2,
oldRecord.get(field2)), is not sufficient.
+ * Requires a deep-copy/rewrite of the evolved field.
+ */
+ private static Object rewriteEvolvedFields(Object datum, Schema newSchema) {
+ switch (newSchema.getType()) {
+ case RECORD:
+ if (!(datum instanceof GenericRecord)) {
+ return datum;
+ }
+ GenericRecord record = (GenericRecord) datum;
+ // if schema of the record being rewritten does not match
+ // with the new schema, some nested records with schema change
+ // will require rewrite.
+ if (!record.getSchema().equals(newSchema)) {
+ GenericRecord newRecord = new GenericData.Record(newSchema);
+ for (Schema.Field f : newSchema.getFields()) {
+ if (record.get(f.name()) == null) {
+ setDefaultVal(newRecord, f);
+ } else {
+ newRecord.put(f.name(),
rewriteEvolvedFields(record.get(f.name()), f.schema()));
+ }
+ }
+ return newRecord;
+ }
+ return datum;
+ case UNION:
+ Integer idx = (newSchema.getTypes().get(0).getType() ==
Schema.Type.NULL) ? 1 : 0;
+ return rewriteEvolvedFields(datum, newSchema.getTypes().get(idx));
+ case ARRAY:
+ List<Object> arrayValue = (List)datum;
+ List<Object> arrayCopy = new GenericData.Array<Object>(
Review comment:
If the datum contained inside the Array/Map is of primitive type, then
no additional schema compatibility check is required. If the datum is a
Record then we are already checking whether newSchema matches with the record
schema, by comparing the hash values.
In other words, similar to the UNION, the nested recursion would take care
of the datum contained in the ARRAY or MAP as well.
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