[
https://issues.apache.org/jira/browse/BEAM-3485?focusedWorklogId=95578&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-95578
]
ASF GitHub Bot logged work on BEAM-3485:
----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Apr/18 16:12
Start Date: 26/Apr/18 16:12
Worklog Time Spent: 10m
Work Description: iemejia commented on a change in pull request #5124:
[BEAM-3485] Fix split generation for Cassandra clusters
URL: https://github.com/apache/beam/pull/5124#discussion_r184447540
##########
File path:
sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/SplitGenerator.java
##########
@@ -0,0 +1,184 @@
+/*
+ * 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.cassandra;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.Lists;
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.List;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** Splits given Cassandra table's token range into splits. */
+final class SplitGenerator {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(SplitGenerator.class);
+
+ private final String partitioner;
+ private final BigInteger rangeMin;
+ private final BigInteger rangeMax;
+ private final BigInteger rangeSize;
+
+ SplitGenerator(String partitioner) {
+ rangeMin = getRangeMin(partitioner);
+ rangeMax = getRangeMax(partitioner);
+ rangeSize = getRangeSize(partitioner);
+ this.partitioner = partitioner;
+ }
+
+ private static BigInteger getRangeMin(String partitioner) {
+ if (partitioner.endsWith("RandomPartitioner")) {
+ return BigInteger.ZERO;
+ } else if (partitioner.endsWith("Murmur3Partitioner")) {
+ return new BigInteger("2").pow(63).negate();
+ } else {
+ throw new UnsupportedOperationException(
+ "Unsupported partitioner. " + "Only Random and Murmur3 are
supported");
+ }
+ }
+
+ private static BigInteger getRangeMax(String partitioner) {
+ if (partitioner.endsWith("RandomPartitioner")) {
+ return new BigInteger("2").pow(127).subtract(BigInteger.ONE);
+ } else if (partitioner.endsWith("Murmur3Partitioner")) {
+ return new BigInteger("2").pow(63).subtract(BigInteger.ONE);
+ } else {
+ throw new UnsupportedOperationException(
+ "Unsupported partitioner. " + "Only Random and Murmur3 are
supported");
+ }
+ }
+
+ static BigInteger getRangeSize(String partitioner) {
+ return
getRangeMax(partitioner).subtract(getRangeMin(partitioner)).add(BigInteger.ONE);
+ }
+
+ /**
+ * Given big0 properly ordered list of tokens, compute at least {@code
totalSplitCount} splits.
+ *
+ * @param totalSplitCount requested total amount of splits. This function
may generate more
+ * splits.
+ * @param ringTokens list of all start tokens in big0 cluster. They have to
be in ring order.
+ * @return big0 list containing at least {@code totalSplitCount} splits.
+ */
+ List<List<RingRange>> generateSplits(long totalSplitCount, List<BigInteger>
ringTokens) {
Review comment:
Can you please add to this documentation a brief discussion on the splitting
strategy, something like:
```The split uses smart coalescence to group token ranges that share the
same replicas together....```
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Issue Time Tracking
-------------------
Worklog Id: (was: 95578)
Time Spent: 5h 20m (was: 5h 10m)
> CassandraIO.read() splitting produces invalid queries
> -----------------------------------------------------
>
> Key: BEAM-3485
> URL: https://issues.apache.org/jira/browse/BEAM-3485
> Project: Beam
> Issue Type: Bug
> Components: io-java-cassandra
> Reporter: Eugene Kirpichov
> Assignee: Alexander Dejanovski
> Priority: Major
> Time Spent: 5h 20m
> Remaining Estimate: 0h
>
> See
> [https://stackoverflow.com/questions/48090668/how-to-increase-dataflow-read-parallelism-from-cassandra/48131264?noredirect=1#comment83548442_48131264]
> As the question author points out, the error is likely that token($pk) should
> be token(pk). This was likely masked by BEAM-3424 and BEAM-3425, and the
> splitting code path effectively was never invoked, and was broken from the
> first PR - so there are likely other bugs.
> When testing this issue, we must ensure good code coverage in an IT against a
> real Cassandra instance.
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