[HUDI-3678] Fix record rewrite of create handle when 'preserveMetadat…

[danny0405]

…a' is true

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[nsivabalan]

reason why I had to rewriteRecord is that, indexexRecord did not have meta fields with update path from the caller. Hence passed in the oldRecord from which we can deduce the meta fields.

For eg,

the return value from combineAndGetUpdate(...) does have the meta fields.

not sure if we can remove it.

[nsivabalan]

Specifically I am talking about this code snippet in HoodieMergeHandle. combinedAvroRecord below does not contain any meta fields. So, if you remove rewriting w/ meta columns, not sure how that would pan out

  public void write(GenericRecord oldRecord) {
    String key = KeyGenUtils.getRecordKeyFromGenericRecord(oldRecord, keyGeneratorOpt);
    boolean copyOldRecord = true;
    if (keyToNewRecords.containsKey(key)) {
      // If we have duplicate records that we are updating, then the hoodie record will be deflated after
      // writing the first record. So make a copy of the record to be merged
      HoodieRecord<T> hoodieRecord = keyToNewRecords.get(key).newInstance();
      try {
        Option<IndexedRecord> combinedAvroRecord =
            hoodieRecord.getData().combineAndGetUpdateValue(oldRecord,
              useWriterSchema ? tableSchemaWithMetaFields : tableSchema,
                config.getPayloadConfig().getProps());
.
.

[danny0405]

Currently we read the old records from base file with metadata fields in schema, see:

hudi/hudi-client/hudi-client-common/src/main/java/org/apache/hudi/table/action/commit/HoodieMergeHelper.java

Line 76 in 52f0498

readSchema = mergeHandle.getWriterSchemaWithMetaFields();

And for new records in the in-coming dataset, the schema also includes the metadata fields.
The combineAndGetUpdateValue method also handle the records with write schema(schema with metadata fields)

[nsivabalan]

left one clarifying question

[hudi-bot]

CI report:

• 1f4b599 UNKNOWN
• 8393a5f Azure: FAILURE

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[danny0405]

The failure is not caused by the patch, so i would just merge it.