apache / apache/parquet-java

Avro RequestedProjection incompatible with Hive written data

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Component: Avro Component: Parquet Priority: Major Type: bug
Dominant language
Java
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Description

I got a Parquet file written by Hive with this schema:
```java

file schema: hive_schema
--------------------------------------------------------------------------------
taxi_id: OPTIONAL BINARY O:UTF8 R:0 D:1
date: OPTIONAL BINARY O:UTF8 R:0 D:1
start_time: OPTIONAL INT64 R:0 D:1
end_time: OPTIONAL INT64 R:0 D:1
min_lat_wgs: OPTIONAL DOUBLE R:0 D:1
min_lng_wgs: OPTIONAL DOUBLE R:0 D:1
max_lat_wgs: OPTIONAL DOUBLE R:0 D:1
max_lng_wgs: OPTIONAL DOUBLE R:0 D:1
first_lat_wgs: OPTIONAL DOUBLE R:0 D:1
first_lng_wgs: OPTIONAL DOUBLE R:0 D:1
last_lat_wgs: OPTIONAL DOUBLE R:0 D:1
last_lng_wgs: OPTIONAL DOUBLE R:0 D:1
gps_log: OPTIONAL F:1
.bag: REPEATED F:1
..array_element: OPTIONAL F:6
...timestamp: OPTIONAL INT64 R:1 D:4
...lat_wgs: OPTIONAL DOUBLE R:1 D:4
...lng_wgs: OPTIONAL DOUBLE R:1 D:4
...item: OPTIONAL INT32 R:1 D:4
...direction: OPTIONAL INT32 R:1 D:4
...vflag: OPTIONAL INT32 R:1 D:4
```
I want to use parquet-avro to read it, and use `AvroReadSupport.setRequestedProjection` to select a subset of field.
```java

{
"type": "record",
"name": "test",
"fields": [
{
"name": "taxi_id",
"type": ["null", "string"]
},
{
"name": "gps_log",
"type": [{
"type": "array",
"items": ["null", {
"name": "point",
"type": "record",
"fields": [
{
"name": "lat_wgs",
"type": ["null", "double"]
},
{
"name": "lng_wgs",
"type": ["null", "double"]
}
]
}]
}],
"default": "null"
}
]
}
```
I try to read data with code: 
```java

Configuration conf = new Configuration(); AvroReadSupport.setRequestedProjection(conf, schema); conf.setBoolean(AvroWriteSupport.WRITE_OLD_LIST_STRUCTURE, false); conf.setBoolean(AvroSchemaConverter.ADD_LIST_ELEMENT_RECORDS, false); AvroParquetReader reader = new AvroParquetReader<>(conf, path);
```
And I got errors:
```java

Exception in thread "main" parquet.io.ParquetDecodingException: The requested schema is not compatible with the file schema. incompatible types:
required group gps_log (LIST) {
repeated group list {
optional group element {
optional double lat_wgs;
optional double lng_wgs;
}
}
} != optional group gps_log (LIST) {
repeated group bag {
optional group array_element {
optional int64 timestamp;
optional double lat_wgs;
optional double lng_wgs;
optional int32 item;
optional int32 direction;
optional int32 vflag;
}
}
}
```
This error doesn't caused by the nullability of `gps_log`. If I mark it nullable in Avro schema, I'll always get a null value.

 

I try to add some code in `AvroSchemaConverter.convertField`:
```java

diff --git a/AvroSchemaConverter.java b/AvroSchemaConverterNew.java
index 0b8076b..48b56dd 100644
--- a/AvroSchemaConverter.java
+++ b/AvroSchemaConverterNew.java
@@ -50,12 +50,17 @@ public class AvroSchemaConverter {
     "parquet.avro.add-list-element-records";
private static final boolean ADD_LIST_ELEMENT_RECORDS_DEFAULT = true;
+ public static final String READ_HIVE_WRITE_FILE =
+    "parquet.avro.read-hive-write-file";
+ private static final boolean READ_HIVE_WRITE_FILE_DEFAULT = false;
+
private final boolean assumeRepeatedIsListElement;
private final boolean writeOldListStructure;
public AvroSchemaConverter() {
     this.assumeRepeatedIsListElement = ADD_LIST_ELEMENT_RECORDS_DEFAULT;
     this.writeOldListStructure = WRITE_OLD_LIST_STRUCTURE_DEFAULT;
+   this.isReadHiveWriteFileDefault = READ_HIVE_WRITE_FILE_DEFAULT;
}
public AvroSchemaConverter(Configuration conf) {
@@ -63,6 +68,9 @@ public class AvroSchemaConverter {
         ADD_LIST_ELEMENT_RECORDS, ADD_LIST_ELEMENT_RECORDS_DEFAULT);
     this.writeOldListStructure = conf.getBoolean(
         WRITE_OLD_LIST_STRUCTURE, WRITE_OLD_LIST_STRUCTURE_DEFAULT);
+   this.isReadHiveWriteFileDefault = conf.getBoolean(
+       READ_HIVE_WRITE_FILE, READ_HIVE_WRITE_FILE_DEFAULT
+   );
}
/**
@@ -137,7 +145,14 @@ public class AvroSchemaConverter {
     if (writeOldListStructure) {
         return ConversionPatterns.listType(repetition, fieldName,
             convertField("array", schema.getElementType(), REPEATED));
-    } else {
+    } else if (isReadHiveWriteFileDefault) {
+       Type elementType = convertField("array_element", schema.getElementType());
+       return new GroupType(
+           repetition,
+           fieldName,
+           LIST,
+           new GroupType(Type.Repetition.REPEATED, "bag", elementType));
+       } else {
         return ConversionPatterns.listOfElements(repetition, fieldName,
             convertField(AvroWriteSupport.LIST_ELEMENT_NAME, schema.getElementType()));
     }
```
It can read data with this file.

 

So is this a compatibility problem in parquet-avro, or just I missed some configuration?

 

 

**Environment**: parquet-mr in CDH 5.14.2 (base version is 1.5.0)

parquet-mr 1.9.0
**Reporter**: [Zejun Li](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=bobotu)

**Note**: *This issue was originally created as [PARQUET-1330](https://issues.apache.org/jira/browse/PARQUET-1330). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with AvroSchemaConverter.convertField and the AvroReadSupport.setRequestedProjection call, then reproduce the mismatch using the supplied Hive schema and Avro projection. Compare the generated LIST structures and the READ_HIVE_WRITE_FILE, WRITE_OLD_LIST_STRUCTURE, and ADD_LIST_ELEMENT_RECORDS settings; done means the expected Hive-written data can be read without an incompatible requested schema.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
data-engineering
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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