'core' ORC extension (apache#7138)

* orc extension reworked to use apache orc map-reduce lib, moved to core extensions, support for flattenSpec, tests, docs

* change binary handling to be compatible with avro and parquet, Rows.objectToStrings now converts byte[] to base64, change date handling

* better docs and tests

* fix it

* formatting

* doc fix

* fix it

* exclude redundant dependencies

* use latest orc-mapreduce, add hadoop jobProperties recommendations to docs

* doc fix

* review stuff and fix binaryAsString

* cache for root level fields

* more better

core/src/main/java/org/apache/druid/data/input/Rows.java

@@ -66,6 +66,9 @@ public static List<String> objectToStrings(final Object inputValue)
     } else if (inputValue instanceof List) {
       // guava's toString function fails on null objects, so please do not use it
       return ((List<?>) inputValue).stream().map(String::valueOf).collect(Collectors.toList());
+    } else if (inputValue instanceof byte[]) {
+      // convert byte[] to base64 encoded string
+      return Collections.singletonList(StringUtils.encodeBase64String((byte[]) inputValue));
     } else {
       return Collections.singletonList(String.valueOf(inputValue));
     }

distribution/pom.xml

@@ -169,6 +169,8 @@
                                         <argument>-c</argument>
                                         <argument>org.apache.druid.extensions:mysql-metadata-storage</argument>
                                         <argument>-c</argument>
+                                        <argument>org.apache.druid.extensions:druid-orc-extensions</argument>
+                                        <argument>-c</argument>
                                         <argument>org.apache.druid.extensions:druid-parquet-extensions</argument>
                                         <argument>-c</argument>
                                         <argument>org.apache.druid.extensions:postgresql-metadata-storage</argument>
@@ -315,8 +317,6 @@
                                         <argument>-c</argument>
                                         <argument>org.apache.druid.extensions.contrib:druid-opentsdb-emitter</argument>
                                         <argument>-c</argument>
-                                        <argument>org.apache.druid.extensions.contrib:druid-orc-extensions</argument>
-                                        <argument>-c</argument>
                                         <argument>org.apache.druid.extensions.contrib:druid-rabbitmq</argument>
                                         <argument>-c</argument>
                                         <argument>org.apache.druid.extensions.contrib:druid-redis-cache</argument>