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Posted to commits@hudi.apache.org by "voonhous (via GitHub)" <gi...@apache.org> on 2026/10/13 13:47:51 UTC

[I] Shredded variant COW upsert fails on DECIMAL leaf: Avro fixed/record name collision on typed_value [hudi]

voonhous opened a new issue, #20307:
URL: https://github.com/apache/hudi/issues/20307

**Describe the problem you faced**

A COW upsert fails when the base file holds a shredded variant column with at least one DECIMAL-typed shredded leaf. The bulk_insert that writes the shredded file succeeds and Spark reads it back correctly; the merge that rewrites the file group fails in the Avro read path with

```
org.apache.hudi.exception.HoodieUpsertException: Failed to compact file group: 6213365d-...
at org.apache.hudi.io.FileGroupReaderBasedMergeHandle.doMerge(FileGroupReaderBasedMergeHandle.java:337)
Caused by: org.apache.hudi.exception.HoodieException: unable to read next record from parquet file
at org.apache.hudi.common.util.ParquetReaderIterator.hasNext(ParquetReaderIterator.java:65)
...
at org.apache.hudi.io.FileGroupReaderBasedMergeHandle.doMerge(FileGroupReaderBasedMergeHandle.java:297)
Caused by: org.apache.hudi.exception.HoodieAvroSchemaException: Failed to parse schema: {"type":"record","name":"hudi_record",...
at org.apache.hudi.common.schema.HoodieSchema$Parser.parse(HoodieSchema.java:1713)
at org.apache.hudi.common.schema.HoodieSchema.parse(HoodieSchema.java:375)
at org.apache.parquet.avro.HoodieAvroReadSupport.init(HoodieAvroReadSupport.java:90)
Caused by: org.apache.avro.AvroTypeException: Undefined schema: k102.typed_value
at org.apache.avro.util.SchemaResolver$ResolvingVisitor.visitNonTerminal(SchemaResolver.java:187)
...
at org.apache.avro.Schema$Parser.parse(Schema.java:1516)
```

Any JSON number with a fractional part is enough to hit this: `parse_json('{"a":1.5}')` stores the value as a decimal, and the inferred shredding schema writes it as `fixed_len_byte_array(8) typed_value (DECIMAL(18,12))`. Unshredded variant columns, and shredded columns whose leaves are all string/int/long/boolean/array, upsert fine.

**Cause**

`HoodieAvroParquetReader.getIndexedRecordIteratorInternal` reads a shredded base file in its shredded shape (`HoodieVariantReconstruction.intermediateSchema()`, from #18938). That schema is built by `VariantSchemaUtils.toShreddedReadSchema(requestedSchema, fileSchema)`, where `fileSchema` is the parquet footer converted by parquet-avro's `AvroSchemaConverter` (`NativeAvroSchemaConverter.java:41`).

parquet-avro names the Avro `fixed` for a DECIMAL `fixed_len_byte_array` leaf after its parquet field, so the leaf becomes a `fixed` called `typed_value`. The enclosing shredded group also converts to a `record` called `typed_value`. Two named types now share the fullname `typed_value`.

The reader then calls `AvroReadSupport.setRequestedProjection(conf, schema.toAvroSchema())` (`HoodieAvroParquetReader.java:199` and `:203`), which stores `schema.toString()`. Avro's `toString` writes each named type once and emits later occurrences as a bare name reference. `HoodieAvroReadSupport.init` re-parses that string (`HoodieAvroReadSupport.java:90`); the bare `"typed_value"` under key `k10` is resolved in that record's namespace (`k102`, from parquet-avro's duplicate-name suffixing), where nothing is defined.

Where the enclosing namespace happens to be the empty one, the same reference resolves to the `typed_value` record instead of the fixed, so the non-throwing form of this is a silent wrong type rather than a failure.

The dumped schema string shows the shape; the DECIMAL leaves are the only ones emitted as references:

```
{"name":"k10","type":{"type":"record","name":"k10","namespace":"k102","fields":[
{"name":"value","type":["null","bytes"],"default":null},
{"name":"typed_value","type":["null","typed_value"],"default":null}]}}
```

No `fixed` named `typed_value` is defined anywhere in the string.

**To Reproduce**

Verified on master `a41f6ea` with the `-Pspark4.1` bundle (Spark 4.1.1, Scala 2.13), COW, Spark datasource writes, default configs (`hoodie.parquet.variant.write.shredding.enabled=true`, inference on):

1. bulk_insert a DataFrame with a `payload` column produced by `parse_json` over JSON documents that contain at least one number with a fractional part, e.g. `{"k3": 0.4375, "k7": "x"}`.
2. upsert a batch that updates some of those keys.

Step 2 fails every time with the trace above. The same input with `hoodie.parquet.variant.write.shredding.enabled=false` on both writes succeeds, and a Spark read of the table written by step 1 returns the correct rows and `variant_get` values.

A one-row SQL form (`insert ... parse_json('{"a":1.5}')` then `update`) is expected to reproduce it as well; the verified run used a 20000-row generated workload.

**Expected behavior**

The upsert succeeds and the merged file keeps the shredded layout (or any layout, as long as the values round-trip).

**Environment Description**

* Hudi version : 1.3.0-SNAPSHOT (master `a41f6ea`)
* Spark version : 4.1.1
* Storage : local filesystem
* Table type : COPY_ON_WRITE

**Additional context**

Existing shredded-variant coverage (`TestVariantShreddingMixedLayouts`, `TestVariantDataType`) only uses integer and string leaves, which is why the Avro-path merge never saw a `fixed` leaf. MOR compaction reads base files through the same reader and is probably affected too; not run.

Fix options: give the DECIMAL `fixed` a path-unique name during footer conversion, or stop round-tripping the projection schema through `toString` in `HoodieAvroParquetReader`.

Related: #18938 (shredded base files through the Avro reader), #18961 (per-file shredding inference on by default, which makes the DECIMAL leaf appear without a forced schema).

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Re: [I] Shredded variant COW upsert fails on DECIMAL leaf: Avro fixed/record name collision on typed_value [hudi]

Posted by "voonhous (via GitHub)" <gi...@apache.org>.

voonhous commented on issue #20307:
URL: https://github.com/apache/hudi/issues/20307#issuecomment-6148001844

   This is required for unblocking lake-loader benchmarking.
   
   I will first need to see why the avro format here is causing issues and if this issue has knock on effects elsewhere. 


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Re: [I] Shredded variant COW upsert fails on DECIMAL leaf: Avro fixed/record name collision on typed_value [hudi]

Posted by "voonhous (via GitHub)" <gi...@apache.org>.

voonhous commented on issue #20307:
URL: https://github.com/apache/hudi/issues/20307#issuecomment-6165794582

   **TLDR:** root cause is a missing namespace: Hudi's Parquet-to-Avro converter (`AvroSchemaConverterWithTimestampNTZ`, copied from parquet-java 1.13.1) names every `fixed` after its field with no namespace, so the DECIMAL `typed_value` leaf collides with the enclosing `typed_value` record. Upstream already fixed this in PARQUET-2456 (apache/parquet-java#1304, 1.14.0); our copy predates it. Fix: #20324.
   


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Re: [I] Shredded variant COW upsert fails on DECIMAL leaf: Avro fixed/record name collision on typed_value [hudi]

Posted by "voonhous (via GitHub)" <gi...@apache.org>.

voonhous closed issue #20307: Shredded variant COW upsert fails on DECIMAL leaf: Avro fixed/record name collision on typed_value
URL: https://github.com/apache/hudi/issues/20307


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