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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5657) Implement size-aware result set loader
Date Fri, 10 Nov 2017 17:47:00 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16247832#comment-16247832
] 

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

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

    https://github.com/apache/drill/pull/914#discussion_r149765040
  
    --- Diff: exec/vector/src/main/java/org/apache/drill/exec/record/MaterializedField.java
---
    @@ -168,6 +174,58 @@ public boolean equals(Object obj) {
                 Objects.equals(this.type, other.type);
       }
     
    +  public boolean isEquivalent(MaterializedField other) {
    +    if (! name.equalsIgnoreCase(other.name)) {
    +      return false;
    +    }
    +
    +    // Requires full type equality, including fields such as precision and scale.
    +    // But, unset fields are equivalent to 0. Can't use the protobuf-provided
    +    // isEquals(), that treats set and unset fields as different.
    +
    +    if (type.getMinorType() != other.type.getMinorType()) {
    +      return false;
    +    }
    +    if (type.getMode() != other.type.getMode()) {
    +      return false;
    +    }
    +    if (type.getScale() != other.type.getScale()) {
    +      return false;
    +    }
    +    if (type.getPrecision() != other.type.getPrecision()) {
    +      return false;
    +    }
    +
    +    // Compare children -- but only for maps, not the internal children
    +    // for Varchar, repeated or nullable types.
    +
    +    if (type.getMinorType() != MinorType.MAP) {
    +      return true;
    +    }
    +
    +    if (children == null  ||  other.children == null) {
    +      return children == other.children;
    +    }
    +    if (children.size() != other.children.size()) {
    +      return false;
    +    }
    +
    +    // Maps are name-based, not position. But, for our
    +    // purposes, we insist on identical ordering.
    +
    +    Iterator<MaterializedField> thisIter = children.iterator();
    +    Iterator<MaterializedField> otherIter = other.children.iterator();
    +    while (thisIter.hasNext()) {
    --- End diff --
    
    isEquivalent requires identical ordering which is a stronger requirement than the guarantee
that the children list is providing. Could we use contains() to find the child and then apply
isEquivalent recursively?



> 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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