qphien commented on a change in pull request #2052:
URL: https://github.com/apache/iceberg/pull/2052#discussion_r554938002
##########
File path: mr/src/main/java/org/apache/iceberg/mr/hive/HiveIcebergSerDe.java
##########
@@ -82,7 +81,17 @@ public void initialize(@Nullable Configuration
configuration, Properties serDePr
}
String[] selectedColumns =
ColumnProjectionUtils.getReadColumnNames(configuration);
- Schema projectedSchema = selectedColumns.length > 0 ?
tableSchema.select(selectedColumns) : tableSchema;
+ // When same table is joined multiple times, it is possible some selected
columns are duplicated,
+ // in this case wrong recordStructField position leads wrong value or
ArrayIndexOutOfBoundException
+ String[] distinctSelectedColumns =
Arrays.stream(selectedColumns).distinct().toArray(String[]::new);
+ Schema projectedSchema = distinctSelectedColumns.length > 0 ?
+ tableSchema.select(distinctSelectedColumns) : tableSchema;
+ // the input split mapper handles does not belong to this table
+ // it is necessary to ensure projectedSchema equals to tableSchema,
+ // or we cannot find selectOperator's column from inspector
+ if (projectedSchema.columns().size() != distinctSelectedColumns.length) {
+ projectedSchema = tableSchema;
+ }
Review comment:
With test case `testSelectedColumnsOverlapJoin`, assuming that mapper
is handling split belongs to table `default.orders`, columns set in
`hive.io.file.readcolumn.names` are [order_id, customer_id], the inspector
created for table `default.customers` just contains column [customer_id], when
table `default.customers` selectOperator is initialized, field `first_name`
cannot be found from inspector we just created, so exception below is thrown
```
cannot find field first_name from
[org.apache.iceberg.mr.hive.serde.objectinspector.IcebergRecordObjectInspector$IcebergRecordStructField@a6807525]
at
org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.getStandardStructFieldRef
```
The cause of this exception is that the schema get from `Schema.select()` is
not what we want, returning an inspector contains all table columns is an easy
workaround to fix this issue.
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