dntjr8096 opened a new issue, #11367:
URL: https://github.com/apache/iceberg/issues/11367
### Apache Iceberg version
1.4.3
### Query engine
Impala
### Please describe the bug 🐞
When migrating a Hive-Parquet table written via Impala or Hive to Iceberg
using the Spark command CALL catalog.system.migrate('hive_table'), reading the
data in Spark SQL fails due to schema compatibility issues.
1. Some Parquet-producing systems (e.g., Impala, Hive, older versions of
Spark SQL) do not differentiate between binary data and strings when writing
the Parquet schema. Spark SQL offers a flag to interpret binary data as strings
to provide compatibility with these systems.
2. If data was written to a Hive-Parquet table (e.g., hive_table) using
Impala, and the table had two columns (col1 as string, and col2 as string), the
Parquet row groups show null for the logical type:
```
* Table Name: hive_table / parquet row groups info*
column_name: col1
physical type: binary
logical type: null
column_name: col2
physical type: binary
logical type: null
```
3. In Iceberg, when trying to read Parquet data in Spark, the
`GenericArrowVectorAccessorFactory` generates an accessor as
`DictionaryBinaryAccessor`. Since `DictionaryBinaryAccessor` does not implement
the getUTF8String function, reading the data in Spark results in an error.
ex.
```java
spark.sql("CALL catalog.sytem.migrate('hive_table')")
spark.sql("select * from hive_table").limit(10).show()
java.lang.UnsupportedOperationException: Unsupported type: UTF8String
at
org.apache.iceberg.arrow.vectorized.ArrowVectorAccessor.getUTF8String(ArrowVectorAccessor.java:81)
at
org.apache.iceberg.spark.data.vectorized.IcebergArrowColumnVector.getUTF8String(IcebergArrowColumnVector.java:138)
at
org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage1.processNext(Unknown
source)
...
```
As an alternative solution, if the PARQUET_ANNOTATE_STRINGS_UTF8 query
option is enabled in Impala (version 2.6 or higher), the logical type will be
annotated as string, avoiding the issue. For example:
```
column_name: col1
physical type: binary
logical type: string
column_name: col2
physical type: binary
logical type: string
```
Something like this needed as a fix
```
...
} else {
switch (primitive.getPrimitiveTypeName()) {
case FIXED_LEN_BYTE_ARRAY:
case BINARY:
return new DictionaryBinaryAccessor<>((IntVector) vector,
dictionary, stringFactorySupplier.get())
...
...
private static class DictionaryBinaryAccessor<
DecimalT, Utf8StringT, ArrayT, ChildVectorT extends AutoCloseable>
extends ArrowVectorAccessor<DecimalT, Utf8StringT, ArrayT,
ChildVectorT> {
private final IntVector offsetVector;
private final Dictionary dictionary;
private final IntVector offsetVector;
private final Utf8StringT[] cache;
DictionaryBinaryAccessor(IntVector vector, Dictionary dictionary, ,
StringFactory<Utf8StringT> stringFactory) {
super(vector);
this.offsetVector = vector;
this.dictionary = dictionary;
this.stringFactory = stringFactory;
this.cache = genericArray(stringFactory.getGenericClass(),
dictionary.getMaxId() + 1);
}
@Override
public final byte[] getBinary(int rowId) {
return dictionary.decodeToBinary(offsetVector.get(rowId)).getBytes();
}
@Override
public final Utf8StringT getUTF8String(int rowId) {
int offset = offsetVector.get(rowId);
if (cache[offset] == null) {
cache[offset] =
stringFactory.ofByteBuffer(dictionary.decodeToBinary(offset).toByteBuffer());
}
return cache[offset];
}
}
```
### Willingness to contribute
- [ ] I can contribute a fix for this bug independently
- [ ] I would be willing to contribute a fix for this bug with guidance from
the Iceberg community
- [X] I cannot contribute a fix for this bug at this time
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