Incorrect type casting while reading HUDI table created with CustomKeyGenerator and unixtimestamp paritioning field

Hi,

I have discovered an issue that doesn't play nicely with the custom key generatosr, basically anything that is not TimestampBasedKeyGenerator or TimestampBasedAvroKeyGenerator.

{{While trying to read a table that was created with these parameters(the rest don't matter):}}
{code:java}
hoodie.datasource.write.recordkey.field=query_id,event_type
hoodie.datasource.write.keygenerator.class=org.apache.hudi.keygen.CustomKeyGenerator
hoodie.datasource.write.partitionpath.field=create_time_epoch_seconds:timestamp
hoodie.deltastreamer.keygen.timebased.timestamp.type=UNIX_TIMESTAMP
hoodie.deltastreamer.keygen.timebased.output.dateformat=yyyy/MM/dd{code}
{color:#172b4d}I get and error that looks like:{color}
{code:java}
22/07/20 20:32:48 DEBUG Spark32HoodieParquetFileFormat: Appending StructType(StructField(create_time_epoch_seconds,LongType,true)) [2022/07/13]
22/07/20 20:32:48 ERROR Executor: Exception in task 0.0 in stage 5.0 (TID 5)
java.lang.ClassCastException: org.apache.spark.unsafe.types.UTF8String cannot be cast to java.lang.Long
    at scala.runtime.BoxesRunTime.unboxToLong(BoxesRunTime.java:107)
    at org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getLong(rows.scala:42)
    at org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getLong$(rows.scala:42)
    at org.apache.spark.sql.catalyst.expressions.GenericInternalRow.getLong(rows.scala:195)
    at org.apache.spark.sql.execution.vectorized.ColumnVectorUtils.populate(ColumnVectorUtils.java:66)
    at org.apache.spark.sql.execution.datasources.parquet.VectorizedParquetRecordReader.initBatch(VectorizedParquetRecordReader.java:245) {code}
Apparently the issue is in _partitionSchemaFromProperties function in file: hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/SparkHoodieTableFileIndex.scala

that checks for a class type it uses StructType of String for.
Once it is any non Timestamp based known class it basically uses whatever type it is and then fails to retrieve the value for.

I have a proposal here which we probably need: Give a user a way to force a string type if needed and add ability to add a prefixed column that contains a processed partition value. It could be done as two separate features.

This problem is critical for me, so I have to change Hoodie source code on my end temporary to make it work.

Here is how I roughly changed the referenced function:

 
{code:java}
/**
* Get the partition schema from the hoodie.properties.
*/
private lazy val _partitionSchemaFromProperties: StructType = {
val tableConfig = metaClient.getTableConfig
val partitionColumns = tableConfig.getPartitionFields

if (partitionColumns.isPresent) {
val partitionFields = partitionColumns.get().map(column => StructField("_hoodie_"+column, StringType))
StructType(partitionFields)
} else {
// If the partition columns have not stored in hoodie.properties(the table that was
// created earlier), we trait it as a non-partitioned table.
logWarning("No partition columns available from hoodie.properties." +
" Partition pruning will not work")
new StructType()
}
} {code}

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-4430
- Type: Sub-task
- Parent: https://issues.apache.org/jira/browse/HUDI-9113
- Affects version(s):
- 0.12.0
- Fix version(s):
- 1.1.0

---

## Comments

20/Jul/22 21:00;vburenin;{{Here is how I read it:}}

 
{code:java}
spark.read().format("org.apache.hudi")
.load(BASE_PATH + "/test_table").createOrReplaceTempView("some_table");
spark.sql("SELECT * FROM some_table").show();
spark.stop();
{code}
 ;;;

---

22/Jul/22 06:28;rmahindra;Looks like your input column is of type string, did you try with the following config:

 
|{{hoodie.deltastreamer.keygen.timebased.timestamp.type="DATE_STRING"}}|

 

and 

 
|{{hoodie.deltastreamer.keygen.timebased.input.dateformat="yyyy-MM-dd'T'HH:mm:ssZ,yyyy-MM-dd'T'HH:mm:ss.SSSZ,yyyyMMdd"}}|

depending on the actual format;;;

---

22/Jul/22 14:02;vburenin;[~rmahindra] The input column is a unix timestamp. It is integer and appears like integer in parquet file. The processed output looks exactly how I would expect. The problem is on the read side. Once I change the code the way I mentioned, I can read the table, the 'create_time_epoch_seconds' appears as integer in the table as well as I also get 
_hoodie_create_time_epoch_seconds containing "2020/07/22" without quotes.

The problem with the original code is that it looks at the hardcoded class names it is using and doesn't allow to use anything else to get a string type:
{code:java}
if (classOf[TimestampBasedKeyGenerator].getName.equalsIgnoreCase(keyGeneratorClassName)
|| classOf[TimestampBasedAvroKeyGenerator].getName.equalsIgnoreCase(keyGeneratorClassName)){code}
 ;;;

---

17/Sep/22 19:12;vburenin;Here is an example PR how it could be fixed: https://github.com/apache/hudi/pull/6172;;;

---

19/Sep/22 19:38;rmahindra;[~alexey.kudinkin] Will help with this.;;;

---

25/Oct/24 11:24;ljain;I have verified that this issue is not seen anymore with the latest fixes in HUDI-7996 and HUDI-8036.
[~vburenin] Can you please try again with the latest master?;;;