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https://issues.apache.org/jira/browse/DRILL-7096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16914154#comment-16914154
]
ASF GitHub Bot commented on DRILL-7096:
---------------------------------------
arina-ielchiieva commented on pull request #1829: DRILL-7096: Develop vector
for canonical Map<K,V>
URL: https://github.com/apache/drill/pull/1829#discussion_r317073646
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetReaderUtility.java
##########
@@ -713,4 +715,63 @@ public static boolean
containsComplexColumn(ParquetMetadata footer, List<SchemaP
}
return false;
}
+
+ /**
+ * Converts list of {@link OriginalType}s to list of {@link
org.apache.drill.common.types.TypeProtos.MajorType}s.
+ * <b>NOTE</b>: current implementation cares about {@link OriginalType#MAP}
only
+ * converting it to {@link
org.apache.drill.common.types.TypeProtos.MinorType#DICT}.
+ * Other original types are converted to {@code null}.
+ *
+ * @param originalTypes list of Parquet's types
+ * @return list containing either {@code null} or type with minor
+ * type {@link
org.apache.drill.common.types.TypeProtos.MinorType#DICT} values
+ */
+ public static List<TypeProtos.MajorType> getComplexTypes(List<OriginalType>
originalTypes) {
+ List<TypeProtos.MajorType> result = new ArrayList<>();
+ if (originalTypes == null) {
+ return result;
+ }
+ for (OriginalType type : originalTypes) {
+ if (type == OriginalType.MAP) {
+ TypeProtos.MajorType drillType = TypeProtos.MajorType.newBuilder()
+ .setMinorType(TypeProtos.MinorType.DICT)
+ .setMode(TypeProtos.DataMode.OPTIONAL)
+ .build();
+ result.add(drillType);
+ } else {
+ result.add(null);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Checks whether group field matches pattern for Logical Map type:
+ *
+ * <map-repetition> group <name> (MAP) {
Review comment:
Use proper html formatting.
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> Develop vector for canonical Map<K,V>
> -------------------------------------
>
> Key: DRILL-7096
> URL: https://issues.apache.org/jira/browse/DRILL-7096
> Project: Apache Drill
> Issue Type: Sub-task
> Reporter: Igor Guzenko
> Assignee: Bohdan Kazydub
> Priority: Major
> Fix For: 1.17.0
>
>
> Canonical Map<K,V> datatype can be represented using combination of three
> value vectors:
> keysVector - vector for storing keys of each map
> valuesVector - vector for storing values of each map
> offsetsVector - vector for storing of start indexes of next each map
> So it's not very hard to create such Map vector, but there is a major issue
> with such map representation. It's hard to search maps values by key in such
> vector, need to investigate some advanced techniques to make such search
> efficient. Or find other more suitable options to represent map datatype in
> world of vectors.
> After question about maps, Apache Arrow developers responded that for Java
> they don't have real Map vector, for now they just have logical Map type
> definition where they define Map like: List< Struct<key:key_type,
> value:value_type> >. So implementation of value vector would be useful for
> Arrow too.
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