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https://issues.apache.org/jira/browse/PARQUET-1879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Gabor Szadovszky reassigned PARQUET-1879:
-----------------------------------------
Assignee: Matthew McMahon
> 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, parquet-format
> Affects Versions: 1.11.0
> Reporter: Matthew McMahon
> Assignee: Matthew McMahon
> Priority: Critical
>
> 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
> ----
> The problem only appears when using a map schema field in the Avro schema.
> For example:
> {code:java}
> {
> "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:java}
> 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:java}
> // 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:java}
> 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:java}
> // 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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