Takuya Ueshin created SPARK-3036:
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Summary: Add MapType containing null value support to Parquet.
Key: SPARK-3036
URL: https://issues.apache.org/jira/browse/SPARK-3036
Project: Spark
Issue Type: Bug
Components: SQL
Reporter: Takuya Ueshin
Priority: Blocker
Current Parquet schema for {{MapType}} is as follows regardless of
{{valueContainsNull}}:
{noformat}
message root {
optional group a (MAP) {
repeated group map (MAP_KEY_VALUE) {
required int32 key;
required int32 value;
}
}
}
{noformat}
and if the map contains {{null}} value, it throws runtime exception.
To handle {{MapType}} containing {{null}} value, the schema should be as
follows if {{valueContainsNull}} is {{true}}:
{noformat}
message root {
optional group a (MAP) {
repeated group map (MAP_KEY_VALUE) {
required int32 key;
optional int32 value;
}
}
}
{noformat}
FYI:
Hive's Parquet writer *always* uses the latter schema, but reader can read from
both schema.
NOTICE:
This change will break backward compatibility when the schema is read from
Parquet metadata ({{"org.apache.spark.sql.parquet.row.metadata"}}).
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