harshagudladona opened a new issue, #14070:
URL: https://github.com/apache/hudi/issues/14070
### Bug Description
**Environment:**
Spark 3.5
Java 11
Hudi 0.14 and 1.0.2
Storage S3
**What happened:**
We are noticing about 20-30% write performance degradation between Hudi 0.14
and 1.0.2
We have profiled the executors by writing the same data between executors
running both versions, and here is the first of few suspects. We will open a
separate bug report as we find more suspects.
Small file Handling:
In both versions, the HoodieMergeHelper.runMerge function, the following
condition ends up being false, without any change to the writer schema during
the test
```
// Check whether the writer schema is simply a projection of the file's
one, ie
// - Its field-set is a proper subset (of the reader schema)
// - There's no schema evolution transformation necessary
boolean isPureProjection = schemaEvolutionTransformerOpt.isEmpty()
&& isStrictProjectionOf(readerSchema, writerSchema);
```
Due to this the record is always rewritten with function
rewriteRecordWithNewSchema
```
executor = ExecutorFactory.create(writeConfig, recordIterator, new
UpdateHandler(mergeHandle), record -> {
HoodieRecord newRecord;
if (schemaEvolutionTransformerOpt.isPresent()) {
newRecord = schemaEvolutionTransformerOpt.get().apply(record);
} else if (shouldRewriteInWriterSchema) {
newRecord = record.rewriteRecordWithNewSchema(recordSchema,
writeConfig.getProps(), writerSchema);
} else {
newRecord = record;
}
```
In this function in hudi 1.x in HoodieAvroUtils.rewriteRecordWithNewSchema,
the following check is added, which seems to be taking significant CPU time.
```
if (oldAvroSchema.equals(newSchema)) {
// there is no need to rewrite if the schema equals.
return oldRecord;
}
//
```
1.x flamegraph
<img width="2325" height="526" alt="Image"
src="https://github.com/user-attachments/assets/4e934182-b445-40dc-be10-40e90bb9af30";
/>
0.14 flamegraph
<img width="2326" height="587" alt="Image"
src="https://github.com/user-attachments/assets/fc132bef-99e1-4330-8fe6-6928cd48173d";
/>
hostspot in 1.0.2
<img width="2332" height="642" alt="Image"
src="https://github.com/user-attachments/assets/98e63658-aabb-4ad9-819b-cc05703eecc5";
/>
**What you expected:**
No performance degradation
**Steps to reproduce:**
1. Write any dataset in 0.14 and 1.0.2 and observe the difference.
### Environment
**Hudi version: 0.14 and 1.0.2**
**Query engine: Spark** (Spark/Flink/Trino etc)
**Relevant configs: Same configurations as the one reported here:
https://github.com/apache/hudi/issues/13995**
### Logs and Stack Trace
_No response_
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