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https://issues.apache.org/jira/browse/HUDI-1509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17259323#comment-17259323
]
Prashant Wason commented on HUDI-1509:
--------------------------------------
I timed the various code fragments involved in the above commit. The timings
are as follows:
private static LinkedHashSet<Field> getCombinedFieldsToWrite(Schema
oldSchema, Schema newSchema) {
LinkedHashSet<Field> allFields = new
LinkedHashSet<>(oldSchema.getFields()); * // 75usec average for this line*
* // 200usec average for the lines below *
for (Schema.Field f : newSchema.getFields()) {
if (!allFields.contains(f) && !isMetadataField(f.name())) {
allFields.add(f);
}
}
return allFields;
}
private static GenericRecord rewrite(GenericRecord record, LinkedHashSet<Field>
fieldsToWrite, Schema newSchema) {
GenericRecord newRecord = new GenericData.Record(newSchema);
for (Schema.Field f : fieldsToWrite) {
if (record.get(f.name()) == null) {
if (f.defaultVal() instanceof JsonProperties.Null) {
newRecord.put(f.name(), null);
} else {
newRecord.put(f.name(), f.defaultVal());
}
} else {
newRecord.put(f.name(), record.get(f.name()));
}
}
*// 3usec for the code above*
*// 75usec for the code below*
if (!GenericData.get().validate(newSchema, newRecord)) {
throw new SchemaCompatibilityException(
"Unable to validate the rewritten record " + record + " against
schema " + newSchema);
}
return newRecord;
}
> Major performance degradation due to rewriting records with default values
> --------------------------------------------------------------------------
>
> Key: HUDI-1509
> URL: https://issues.apache.org/jira/browse/HUDI-1509
> Project: Apache Hudi
> Issue Type: Bug
> Reporter: Prashant Wason
> Priority: Blocker
>
> During the in-house testing for 0.5x to 0.6x release upgrade, I have detected
> a performance degradation for writes into HUDI. I have traced the issue due
> to the changes in the following commit
> [[HUDI-727]: Copy default values of fields if not present when rewriting
> incoming record with new
> schema|https://github.com/apache/hudi/commit/6d7ca2cf7e441ad19d32d7a25739e454f39ed253]
> I wrote a unit test to reduce the scope of testing as follows:
> # Take an existing parquet file from production dataset (size=690MB,
> #records=960K)
> # Read all the records from this parquet into a JavaRDD
> # Time the call HoodieWriteClient.bulkInsertPrepped().
> (bulkInsertParallelism=1)
> The above scenario is directly taken from our production pipelines where each
> executor will ingest about a million record creating a single parquet file in
> a COW dataset. This is bulk insert only dataset.
> The time to complete the bulk insert prepped *decreased from 680seconds to
> 380seconds* when I reverted the above commit.
> Schema details: This HUDI dataset uses a large schema with 51 fields in the
> record.
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