[
https://issues.apache.org/jira/browse/BEAM-7450?focusedWorklogId=260579&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-260579
]
ASF GitHub Bot logged work on BEAM-7450:
----------------------------------------
Author: ASF GitHub Bot
Created on: 14/Jun/19 17:14
Start Date: 14/Jun/19 17:14
Worklog Time Spent: 10m
Work Description: jkff commented on pull request #8718: [BEAM-7450]
Support unbounded reads with HCatalogIO
URL: https://github.com/apache/beam/pull/8718#discussion_r293900552
##########
File path:
sdks/java/io/hcatalog/src/main/java/org/apache/beam/sdk/io/hcatalog/PartitionReaderFn.java
##########
@@ -0,0 +1,111 @@
+/*
+ * 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.beam.sdk.io.hcatalog;
+
+import static
org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkArgument;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import org.apache.beam.sdk.io.hcatalog.HCatalogIO.Read;
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.values.KV;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hive.metastore.IMetaStoreClient;
+import org.apache.hadoop.hive.metastore.api.Partition;
+import org.apache.hive.hcatalog.common.HCatConstants;
+import org.apache.hive.hcatalog.data.HCatRecord;
+import org.apache.hive.hcatalog.data.transfer.DataTransferFactory;
+import org.apache.hive.hcatalog.data.transfer.HCatReader;
+import org.apache.hive.hcatalog.data.transfer.ReadEntity;
+import org.apache.hive.hcatalog.data.transfer.ReaderContext;
+
+/** Reads partition at a given index. */
+class PartitionReaderFn extends DoFn<KV<Read, Integer>, HCatRecord> {
+ private transient IMetaStoreClient metaStoreClient;
+ private Map<String, String> configProperties;
+
+ public PartitionReaderFn(Map<String, String> configProperties) {
+ this.configProperties = configProperties;
+ }
+
+ private ReaderContext getReaderContext(Read readRequest, Integer
partitionIndexToRead)
+ throws Exception {
+ final List<Partition> partitions =
+ metaStoreClient.listPartitions(
+ readRequest.getDatabase(), readRequest.getTable(),
Short.MAX_VALUE);
+ final Partition partition = partitions.get(partitionIndexToRead);
+ checkArgument(
+ partition != null, "Unable to find a partition to read at index " +
partitionIndexToRead);
+
+ final int desiredSplitCount = HCatalogUtils.getSplitCount(readRequest,
partition);
+ final List<String> values = partition.getValues();
+ final List<String> partitionCols = readRequest.getPartitionCols();
+ checkArgument(
+ values.size() == partitionCols.size(),
+ "Number of input partitions should be equal to the values of list
partition values.");
+
+ List<String> filter = new ArrayList<>();
+ for (int i = 0; i < partitionCols.size(); i++) {
+ filter.add(partitionCols.get(i) + "=" + "'" + values.get(i) + "'");
+ }
+ final String filterString = String.join(" and ", filter);
+
+ ReadEntity entity =
+ new ReadEntity.Builder()
+ .withDatabase(readRequest.getDatabase())
+ .withFilter(filterString)
+ .withTable(readRequest.getTable())
+ .build();
+ // pass the 'desired' split count as an hint to the API
+ Map<String, String> configProps = new
HashMap<>(readRequest.getConfigProperties());
+ configProps.put(
+ HCatConstants.HCAT_DESIRED_PARTITION_NUM_SPLITS,
String.valueOf(desiredSplitCount));
+ return DataTransferFactory.getHCatReader(entity,
configProps).prepareRead();
+ }
+
+ @ProcessElement
+ public void processElement(ProcessContext c) throws Exception {
+ final Read readRequest = c.element().getKey();
+ final Integer partitionIndexToRead = c.element().getValue();
+ ReaderContext readerContext = getReaderContext(readRequest,
partitionIndexToRead);
+ for (int i = 0; i < readerContext.numSplits(); i++) {
Review comment:
Why do we need a nested loop here: is it possible to just read the whole
partition without "splitting" it?
If you want to read the splits of a partition in parallel, then you need to
split this into two DoFn's with a reshuffle in between.
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Issue Time Tracking
-------------------
Worklog Id: (was: 260579)
Time Spent: 10h 40m (was: 10.5h)
> Support unbounded reads with HCatalogIO
> ---------------------------------------
>
> Key: BEAM-7450
> URL: https://issues.apache.org/jira/browse/BEAM-7450
> Project: Beam
> Issue Type: New Feature
> Components: io-java-hcatalog
> Reporter: Ankit Jhalaria
> Assignee: Ankit Jhalaria
> Priority: Minor
> Fix For: 2.14.0
>
> Time Spent: 10h 40m
> Remaining Estimate: 0h
>
> # Current version of HcatalogIO is a bounded source.
> # While migrating our jobs to aws, we realized that it would be helpful to
> have an unbounded hcat reader that can behave as an unbounded source and
> polls for new partitions as and when they become available.
> # I have used splittable pardo(s) to do this. There is a flag that can be
> set to treat this as a bounded source which will terminate if that flag is
> set.
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