Matthew McMahon created PARQUET-1879:
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Summary: Apache Arrow can not read a Parquet File written with
Parqet-Avro 1.11.0 with a Map field
Key: PARQUET-1879
URL: https://issues.apache.org/jira/browse/PARQUET-1879
Project: Parquet
Issue Type: Bug
Components: parquet-avro
Affects Versions: 1.11.0
Reporter: Matthew McMahon
>From my
>[StackOverflow|[https://stackoverflow.com/questions/62504757/issue-with-loading-parquet-data-into-snowflake-cloud-database-when-written-with]]
> in relation to an issue I'm having with getting Snowflake (Cloud DB) to load
>Parquet files written with version 1.11.0
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The problem only appears when using a map schema field in the Avro schema. For
example:
{code}
{
"name": "FeatureAmounts",
"type": {
"type": "map",
"values": "records.MoneyDecimal"
}
}
{code}
When using Parquet-Avro to write the file, a bad Parquet schema ends up with,
for example
{code}
message record.ResponseRecord {
required binary GroupId (STRING);
required int64 EntryTime (TIMESTAMP(MILLIS,true));
required int64 HandlingDuration;
required binary Id (STRING);
optional binary ResponseId (STRING);
required binary RequestId (STRING);
optional fixed_len_byte_array(12) CostInUSD (DECIMAL(28,15));
required group FeatureAmounts (MAP) {
repeated group map (MAP_KEY_VALUE) {
required binary key (STRING);
required fixed_len_byte_array(12) value (DECIMAL(28,15));
}
}
}
{code}
>From the great answer to my StackOverflow, it seems the issue is that the
>1.11.0 Parquet-Avro is still using the legacy MAP_KEY_VALUE converted type,
>that has no logical type equivalent. From the comment on
>[LogicalTypeAnnotation](https://github.com/apache/parquet-mr/blob/84c954d8a4feef2d9bdad7a236a7268ef71a1c25/parquet-column/src/main/java/org/apache/parquet/schema/LogicalTypeAnnotation.java#L904)
{code}
// This logical type annotation is implemented to support backward
compatibility with ConvertedType.
// The new logical type representation in parquet-format doesn't have any
key-value type,
// thus this annotation is mapped to UNKNOWN. This type shouldn't be used.
{code}
However, it seems this is being written with the latest 1.11.0, which then
causes Apache Arrow to fail with
{code}
Logical type Null can not be applied to group node
{code}
As it appears that
[Arrow](https://github.com/apache/arrow/blob/master/cpp/src/parquet/types.cc#L629-L632)
only looks for the new logical type of Map or List, therefore this causes an
error.
I have seen in Parquet Formats that
[LogicalTypes]{https://github.com/apache/parquet-format/blob/master/LogicalTypes.md}
should be something like
{code}
// Map<String, Integer>
required group my_map (MAP) {
repeated group key_value {
required binary key (UTF8);
optional int32 value;
}
}
{code}
Is this on the correct path?
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