AvroReadSupport.setRequestedProjection in 1.11.1+ not backwards compatible with MAPS
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Description
using AvroReadSupport.setRequestedProjection in 1.11.1 reading a 1.10.0 generated parquet file sets MAP fields to null (and vice versa 1.10.0 reader against a 1.11.1 generated file)
- Not using a projected schema works, the map fields are converted correctly.
In my case. Parquet file is generated by hive
```java
CREATE TABLE parquetmaptest (
a string,
b MAP
)
STORED AS PARQUET
tblproperties(
"parquet.compression"="SNAPPY"
);
insert into parquetmaptest select "a",map("k1","v1","k2","v2");
```
Using parquet-avro 1.11.1 (and appropriate dependencies) result in field "b" being null.
```java
data:null
row:{"a": "a", "b": null}
```
Using parquet-avro 1.11.0 (and appropriate dependencies) result in field "b" being the right map value.
```java
data:{k1=v1, k2=v2}
row:{"a": "a", "b": {"k1": "v1", "k2": "v2"}}
```
**Reporter**: [Bil Bingham](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=bilbingham)
#### Original Issue Attachments:
- [PQMapTest.java](https://issues.apache.org/jira/secure/attachment/13024749/PQMapTest.java)
**Note**: *This issue was originally created as [PARQUET-2039](https://issues.apache.org/jira/browse/PARQUET-2039). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*
Contributor guide
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Research direction
Start with the attached PQMapTest.java and the AvroReadSupport.setRequestedProjection path, comparing parquet-avro 1.11.1 with 1.10.0 on the Hive-generated MAP file. Reproduce the projected-read failure first; done means projected map fields remain populated when files and readers use either version.
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
- Mostly clear
- Newbie friendliness
- 35/100