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https://issues.apache.org/jira/browse/DRILL-6340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16514660#comment-16514660
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ASF GitHub Bot commented on DRILL-6340:
---------------------------------------
Ben-Zvi commented on a change in pull request #1302: DRILL-6340: Output Batch
Control in Project using the RecordBatchSizer
URL: https://github.com/apache/drill/pull/1302#discussion_r195891265
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/project/ProjectMemoryManager.java
##########
@@ -0,0 +1,315 @@
+/*
+ * 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.physical.impl.project;
+
+import org.apache.drill.common.expression.LogicalExpression;
+import org.apache.drill.common.types.TypeProtos;
+import org.apache.drill.common.types.TypeProtos.DataMode;
+import org.apache.drill.common.types.TypeProtos.MajorType;
+import org.apache.drill.common.types.TypeProtos.MinorType;
+import
org.apache.drill.exec.physical.impl.project.OutputWidthExpression.VarLenReadExpr;
+import org.apache.drill.exec.record.RecordBatch;
+import org.apache.drill.exec.record.RecordBatchMemoryManager;
+import org.apache.drill.exec.record.RecordBatchSizer;
+import org.apache.drill.exec.record.TypedFieldId;
+import org.apache.drill.exec.vector.FixedWidthVector;
+import org.apache.drill.exec.vector.ValueVector;
+import
org.apache.drill.exec.physical.impl.project.OutputWidthExpression.FixedLenExpr;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ *
+ * ProjectMemoryManager(PMM) is used to estimate the size of rows produced by
ProjectRecordBatch.
+ * The PMM works as follows:
+ *
+ * Setup phase: As and when ProjectRecordBatch creates or transfers a field,
it registers the field with PMM.
+ * If the field is a variable width field, PMM records the expression that
produces the variable
+ * width field. The expression is a tree of LogicalExpressions. The PMM walks
this tree of LogicalExpressions
+ * to produce a tree of OutputWidthExpressions. The widths of Fixed width
fields are just accumulated into a single
+ * total. Note: The PMM, currently, cannot handle new complex fields, it just
uses a hard-coded estimate for such fields.
+ *
+ *
+ * Execution phase: Just before a batch is processed by Project, the PMM walks
the tree of OutputWidthExpressions
+ * and conversts them to FixedWidthExpressions. It uses the RecordBatchSizer
and the function annotations to do this conversion.
Review comment:
"converts"
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> Output Batch Control in Project using the RecordBatchSizer
> ----------------------------------------------------------
>
> Key: DRILL-6340
> URL: https://issues.apache.org/jira/browse/DRILL-6340
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Relational Operators
> Reporter: Karthikeyan Manivannan
> Assignee: Karthikeyan Manivannan
> Priority: Major
> Labels: doc-impacting
> Fix For: 1.14.0
>
>
> This bug is for tracking the changes required to implement Output Batch
> Sizing in Project using the RecordBatchSizer. The challenge in doing this
> mainly lies in dealing with expressions that produce variable-length columns.
> The following doc talks about some of the design approaches for dealing with
> such variable-length columns.
> [https://docs.google.com/document/d/1h0WsQsen6xqqAyyYSrtiAniQpVZGmQNQqC1I2DJaxAA/edit?usp=sharing]
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