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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5657) Implement size-aware result set loader
Date Wed, 09 Aug 2017 00:03:00 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119210#comment-16119210
] 

ASF GitHub Bot commented on DRILL-5657:
---------------------------------------

Github user bitblender commented on a diff in the pull request:

    https://github.com/apache/drill/pull/866#discussion_r130429208
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/physical/rowSet/TupleSchema.java
---
    @@ -0,0 +1,91 @@
    +/*
    + * 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.rowSet;
    +
    +import org.apache.drill.exec.physical.rowSet.impl.MaterializedSchema;
    +import org.apache.drill.exec.record.BatchSchema;
    +import org.apache.drill.exec.record.MaterializedField;
    +
    +/**
    + * Defines the schema of a tuple: either the top-level row or a nested
    + * "map" (really structure). A schema is a collection of columns (backed
    + * by vectors in the loader itself.) Columns are accessible by name or
    + * index. New columns may be added at any time; the new column takes the
    + * next available index.
    + */
    +
    +public interface TupleSchema {
    +
    +  public interface TupleColumnSchema {
    +    MaterializedField schema();
    +
    +    /**
    +     * Report if a column is selected.
    +     * @param colIndex index of the column to check
    +     * @return true if the column is selected (data is collected),
    +     * false if the column is unselected (data is discarded)
    +     */
    +
    +    boolean isSelected();
    --- End diff --
    
    What does it mean for a  column to be selected? Selected in the query?


> Implement size-aware result set loader
> --------------------------------------
>
>                 Key: DRILL-5657
>                 URL: https://issues.apache.org/jira/browse/DRILL-5657
>             Project: Apache Drill
>          Issue Type: Improvement
>    Affects Versions: Future
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>             Fix For: Future
>
>
> A recent extension to Drill's set of test tools created a "row set" abstraction to allow
us to create, and verify, record batches with very few lines of code. Part of this work involved
creating a set of "column accessors" in the vector subsystem. Column readers provide a uniform
API to obtain data from columns (vectors), while column writers provide a uniform writing
interface.
> DRILL-5211 discusses a set of changes to limit value vectors to 16 MB in size (to avoid
memory fragmentation due to Drill's two memory allocators.) The column accessors have proven
to be so useful that they will be the basis for the new, size-aware writers used by Drill's
record readers.
> A step in that direction is to retrofit the column writers to use the size-aware {{setScalar()}}
and {{setArray()}} methods introduced in DRILL-5517.
> Since the test framework row set classes are (at present) the only consumer of the accessors,
those classes must also be updated with the changes.
> This then allows us to add a new "row mutator" class that handles size-aware vector writing,
including the case in which a vector fills in the middle of a row.



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