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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4735) Count(dir0) on parquet returns 0 result
Date Wed, 09 Aug 2017 14:40:01 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4735?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16120010#comment-16120010
] 

ASF GitHub Bot commented on DRILL-4735:
---------------------------------------

GitHub user arina-ielchiieva opened a pull request:

    https://github.com/apache/drill/pull/900

    DRILL-4735: ConvertCountToDirectScan rule enhancements

    1. ConvertCountToDirectScan rule will be applicable for 2 or more COUNT aggregates.
    To achieve this DynamicPojoRecordReader was added which accepts any number of columns,
    on the contrary with PojoRecordReader which depends on class fields.
    AbstractPojoRecordReader class was added to factor out common logic for these two readers.
    
    2. ConvertCountToDirectScan will distinguish between missing, directory and implicit columns.
    For missing columns count will be set 0, for implicit to the total records count
    since implicit columns are based on files and there is no data without a file.
    If directory column will be encountered, rule won't be applied.
    
    3. MetadataDirectGroupScan class was introduced to indicate which files statistics for
used.
    
    Details in Jira [DRILL-4735](https://issues.apache.org/jira/browse/DRILL-4735).

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/arina-ielchiieva/drill DRILL-4735

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/drill/pull/900.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #900
    
----
commit 031a5b04ae430dbae015d88089c6d10623b9e87a
Author: Arina Ielchiieva <arina.yelchiyeva@gmail.com>
Date:   2017-07-20T16:26:44Z

    DRILL-4735: ConvertCountToDirectScan rule enhancements
    
    1. ConvertCountToDirectScan rule will be applicable for 2 or more COUNT aggregates.
    To achieve this DynamicPojoRecordReader was added which accepts any number of columns,
    on the contrary with PojoRecordReader which depends on class fields.
    AbstractPojoRecordReader class was added to factor out common logic for these two readers.
    
    2. ConvertCountToDirectScan will distinguish between missing, directory and implicit columns.
    For missing columns count will be set 0, for implicit to the total records count
    since implicit columns are based on files and there is no data without a file.
    If directory column will be encountered, rule won't be applied.
    CountsCollector class was introduced to encapsulate counts collection logic.
    
    3. MetadataDirectGroupScan class was introduced to indicate to the user when metadata
was used
    during calculation and for which files it was applied.

commit f3fa3dc2e2a876a21f1ce51b74dfd2544201f6f6
Author: Arina Ielchiieva <arina.yelchiyeva@gmail.com>
Date:   2017-08-08T13:18:37Z

    DRILL-4735: Changes after code review.

----


> Count(dir0) on parquet returns 0 result
> ---------------------------------------
>
>                 Key: DRILL-4735
>                 URL: https://issues.apache.org/jira/browse/DRILL-4735
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization, Storage - Parquet
>    Affects Versions: 1.0.0, 1.4.0, 1.6.0, 1.7.0
>            Reporter: Krystal
>            Assignee: Arina Ielchiieva
>            Priority: Critical
>
> Selecting a count of dir0, dir1, etc against a parquet directory returns 0 rows.
> select count(dir0) from `min_max_dir`;
> +---------+
> | EXPR$0  |
> +---------+
> | 0       |
> +---------+
> select count(dir1) from `min_max_dir`;
> +---------+
> | EXPR$0  |
> +---------+
> | 0       |
> +---------+
> If I put both dir0 and dir1 in the same select, it returns expected result:
> select count(dir0), count(dir1) from `min_max_dir`;
> +---------+---------+
> | EXPR$0  | EXPR$1  |
> +---------+---------+
> | 600     | 600     |
> +---------+---------+
> Here is the physical plan for count(dir0) query:
> {code}
> 00-00    Screen : rowType = RecordType(BIGINT EXPR$0): rowcount = 20.0, cumulative cost
= {22.0 rows, 22.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1346
> 00-01      Project(EXPR$0=[$0]) : rowType = RecordType(BIGINT EXPR$0): rowcount = 20.0,
cumulative cost = {20.0 rows, 20.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1345
> 00-02        Project(EXPR$0=[$0]) : rowType = RecordType(BIGINT EXPR$0): rowcount = 20.0,
cumulative cost = {20.0 rows, 20.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1344
> 00-03          Scan(groupscan=[org.apache.drill.exec.store.pojo.PojoRecordReader@3da85d3b[columns
= null, isStarQuery = false, isSkipQuery = false]]) : rowType = RecordType(BIGINT count):
rowcount = 20.0, cumulative cost = {20.0 rows, 20.0 cpu, 0.0 io, 0.0 network, 0.0 memory},
id = 1343
> {code}
> Here is part of the explain plan for the count(dir0) and count(dir1) in the same select:
> {code}
> 00-00    Screen : rowType = RecordType(BIGINT EXPR$0, BIGINT EXPR$1): rowcount = 60.0,
cumulative cost = {1206.0 rows, 15606.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1623
> 00-01      Project(EXPR$0=[$0], EXPR$1=[$1]) : rowType = RecordType(BIGINT EXPR$0, BIGINT
EXPR$1): rowcount = 60.0, cumulative cost = {1200.0 rows, 15600.0 cpu, 0.0 io, 0.0 network,
0.0 memory}, id = 1622
> 00-02        StreamAgg(group=[{}], EXPR$0=[COUNT($0)], EXPR$1=[COUNT($1)]) : rowType
= RecordType(BIGINT EXPR$0, BIGINT EXPR$1): rowcount = 60.0, cumulative cost = {1200.0 rows,
15600.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1621
> 00-03          Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=maprfs:/drill/testdata/min_max_dir/1999/Apr/voter20.parquet/0_0_0.parquet],
ReadEntryWithPath [path=maprfs:/drill/testdata/min_max_dir/1999/MAR/voter15.parquet/0_0_0.parquet],
ReadEntryWithPath [path=maprfs:/drill/testdata/min_max_dir/1985/jan/voter5.parquet/0_0_0.parquet],
ReadEntryWithPath [path=maprfs:/drill/testdata/min_max_dir/1985/apr/voter60.parquet/0_0_0.parquet],...,
ReadEntryWithPath [path=maprfs:/drill/testdata/min_max_dir/2014/jul/voter35.parquet/0_0_0.parquet]],
selectionRoot=maprfs:/drill/testdata/min_max_dir, numFiles=16, usedMetadataFile=false, columns=[`dir0`,
`dir1`]]]) : rowType = RecordType(ANY dir0, ANY dir1): rowcount = 600.0, cumulative cost =
{600.0 rows, 1200.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 1620
> {code}
> Notice that in the first case, "org.apache.drill.exec.store.pojo.PojoRecordReader" is
used.



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