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https://issues.apache.org/jira/browse/DRILL-5956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17059215#comment-17059215
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ASF GitHub Bot commented on DRILL-5956:
---------------------------------------
paul-rogers commented on pull request #1888: DRILL-5956: Add Storage Plugin for
Apache Druid
URL: https://github.com/apache/drill/pull/1888#discussion_r352263150
##########
File path:
contrib/storage-druid/src/main/java/org/apache/drill/exec/store/druid/DruidRecordReader.java
##########
@@ -0,0 +1,173 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.store.druid;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.drill.common.exceptions.DrillRuntimeException;
+import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.common.expression.SchemaPath;
+import org.apache.drill.exec.ops.FragmentContext;
+import org.apache.drill.exec.ops.OperatorContext;
+import org.apache.drill.exec.physical.impl.OutputMutator;
+import org.apache.drill.exec.store.AbstractRecordReader;
+import org.apache.drill.exec.store.druid.druid.DruidSelectResponse;
+import org.apache.drill.exec.store.druid.druid.PagingIdentifier;
+import org.apache.drill.exec.store.druid.druid.PagingSpec;
+import org.apache.drill.exec.store.druid.druid.SelectQuery;
+import org.apache.drill.exec.vector.complex.fn.JsonReader;
+import org.apache.drill.exec.vector.complex.impl.VectorContainerWriter;
+import org.apache.drill.shaded.guava.com.google.common.collect.ImmutableList;
+import org.apache.drill.shaded.guava.com.google.common.collect.Sets;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+public class DruidRecordReader extends AbstractRecordReader {
+
+ private static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(DruidRecordReader.class);
+ private DruidStoragePlugin plugin;
+ private final DruidSubScan.DruidSubScanSpec scanSpec;
+ private List<String> dimensions;
+ private String filters;
+ private ArrayList<PagingIdentifier> pagingIdentifiers = new ArrayList<>();
+
+ private JsonReader jsonReader;
+ private VectorContainerWriter writer;
+
+ private OutputMutator output;
+ private OperatorContext context;
+ private final FragmentContext fragmentContext;
+
+ private ObjectMapper objectMapper = new ObjectMapper();
+
+ public DruidRecordReader(DruidSubScan.DruidSubScanSpec subScanSpec,
List<SchemaPath> projectedColumns,
+ FragmentContext context, DruidStoragePlugin
plugin) {
+ dimensions = new ArrayList<String>();
+ setColumns(projectedColumns);
+ this.plugin = plugin;
+ scanSpec = subScanSpec;
+ fragmentContext = context;
+ this.filters = subScanSpec.getFilter();
+ }
+
+ @Override
+ protected Collection<SchemaPath> transformColumns(Collection<SchemaPath>
projectedColumns) {
+ Set<SchemaPath> transformed = Sets.newLinkedHashSet();
+ if (isStarQuery()) {
+ transformed.add(SchemaPath.STAR_COLUMN);
+ } else {
+ for (SchemaPath column : projectedColumns) {
+ String fieldName = column.getRootSegment().getPath();
+ transformed.add(column);
+ this.dimensions.add(fieldName);
+ }
+ }
+ return transformed;
+ }
+
+ @Override
+ public void setup(OperatorContext context, OutputMutator output) throws
ExecutionSetupException {
+ this.context = context;
+ this.output = output;
+ this.writer = new VectorContainerWriter(output);
+
+ //Lists.newArrayList(getColumns()), true, false, false
+ this.jsonReader =
+ new JsonReader.Builder(fragmentContext.getManagedBuffer())
+ .schemaPathColumns(ImmutableList.copyOf(getColumns()))
+ .skipOuterList(true)
+ .build();
+ logger.debug(" Initialized JsonRecordReader. ");
+ }
+
+ @Override
+ public int next() {
Review comment:
Ideally, we'd return Druid responses in Drill batches up to some maximum
record count, say 1000. This means that a single Druid query might be split
into multiple Drill batches, if the number of returned records is large.
However, it seems here each call to `next()` executes query and returns all
results. Maybe there was some partitioning to split each query (the
`DruidWork`) so that each returns a fixed number of records?
If so, the second call to `next()` should return 0 so that Drill knows the
scan is done.
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> Add Storage Plugin for Apache Druid
> -----------------------------------
>
> Key: DRILL-5956
> URL: https://issues.apache.org/jira/browse/DRILL-5956
> Project: Apache Drill
> Issue Type: Wish
> Components: Storage - Other
> Reporter: Jiaqi Liu
> Priority: Major
> Labels: Enhancement, Storage-Plugin
> Fix For: 1.18.0
>
>
> As more and more companies are using Druid for mission-critical industrial
> products, Drill could gain much more popularity with Druid as one of its
> supported storage plugin so that uses could easily bind Druid cluster to
> running Drill instance
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