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https://issues.apache.org/jira/browse/DRILL-4446?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15177027#comment-15177027
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ASF GitHub Bot commented on DRILL-4446:
---------------------------------------
Github user laurentgo commented on a diff in the pull request:
https://github.com/apache/drill/pull/403#discussion_r54828997
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/fragment/DistributionAffinity.java
---
@@ -0,0 +1,61 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.planner.fragment;
+
+/**
+ * Describes an operator's endpoint assignment requirements.
+ */
+public enum DistributionAffinity {
+ /**
+ * No affinity to any endpoints. Operator can run on any endpoint.
+ */
+ NONE(0, SoftAffinityFragmentParallelizer.INSTANCE),
+
+ /**
+ * Operator has soft distribution affinity to one or more endpoints.
Operator performs better when fragments are
+ * assigned to the endpoints with affinity, but not a mandatory
requirement.
+ */
+ SOFT(1, SoftAffinityFragmentParallelizer.INSTANCE),
+
+ /**
+ * Hard distribution affinity to one or more endpoints. Fragments having
the operator must be scheduled on the nodes
+ * with affinity.
+ */
+ HARD(2, HardAffinityFragmentParallelizer.INSTANCE);
+
+ private int level;
+ private FragmentParallelizer fragmentParallelizer;
+
+ DistributionAffinity(final int level, final FragmentParallelizer
fragmentParallelizer) {
+ this.level = level;
+ this.fragmentParallelizer = fragmentParallelizer;
+ }
+
+ public FragmentParallelizer getFragmentParallelizer() {
+ return fragmentParallelizer;
+ }
+
+ /**
+ * Is the current DistributionAffinity less or equal restrictive than
the given DistributionAffinity?
+ * @param distributionAffinity
+ * @return
+ */
+ public boolean isLessOrEqualRestrictive(final DistributionAffinity
distributionAffinity) {
--- End diff --
name suggestion change: lessThanOrEqualTo? At the same time, this enum
implements the Comparable<DistributionAffinity> interface, so as long as the
level is the same as the index, it might be enough...
> Improve current fragment parallelization module
> -----------------------------------------------
>
> Key: DRILL-4446
> URL: https://issues.apache.org/jira/browse/DRILL-4446
> Project: Apache Drill
> Issue Type: New Feature
> Affects Versions: 1.5.0
> Reporter: Venki Korukanti
> Assignee: Venki Korukanti
> Fix For: 1.6.0
>
>
> Current fragment parallelizer {{SimpleParallelizer.java}} can’t handle
> correctly the case where an operator has mandatory scheduling requirement for
> a set of DrillbitEndpoints and affinity for each DrillbitEndpoint (i.e how
> much portion of the total tasks to be scheduled on each DrillbitEndpoint). It
> assumes that scheduling requirements are soft (except one case where Mux and
> DeMux case where mandatory parallelization requirement of 1 unit).
> An example is:
> Cluster has 3 nodes running Drillbits and storage service on each. Data for a
> table is only present at storage services in two nodes. So a GroupScan needs
> to be scheduled on these two nodes in order to read the data. Storage service
> doesn't support (or costly) reading data from remote node.
> Inserting the mandatory scheduling requirements within existing
> SimpleParallelizer is not sufficient as you may end up with a plan that has a
> fragment with two GroupScans each having its own hard parallelization
> requirements.
> Proposal is:
> Add a property to each operator which tells what parallelization
> implementation to use. Most operators don't have any particular strategy
> (such as Project or Filter), they depend on incoming operator. Current
> existing operators which have requirements (all existing GroupScans) default
> to current parallelizer {{SimpleParallelizer}}. {{Screen}} defaults to new
> mandatory assignment parallelizer. It is possible that PhysicalPlan generated
> can have a fragment with operators having different parallelization
> strategies. In that case an exchange is inserted in between operators where a
> change in parallelization strategy is required.
> Will send a detailed design doc.
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