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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4287) Incorrect aggregate query results when stats are disable for parallelization
Date Tue, 31 Oct 2017 06:59:02 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16226354#comment-16226354
] 

James Taylor commented on PHOENIX-4287:
---------------------------------------

Good catch, [~samarthjain]. Minor nit: it might be a little more clear to just have a new
local variable like initialKeyBytes before the inner while loop that stores the current value
of currentKeyBytes that you can use to set currentKeyBytes back to if you're not using stats
for parallelization.

> Incorrect aggregate query results when stats are disable for parallelization
> ----------------------------------------------------------------------------
>
>                 Key: PHOENIX-4287
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4287
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.12.0
>         Environment: HBase 1.3.1
>            Reporter: Mujtaba Chohan
>            Assignee: Samarth Jain
>              Labels: localIndex
>             Fix For: 4.12.1
>
>         Attachments: PHOENIX-4287.patch, PHOENIX-4287_v2.patch, PHOENIX-4287_v3.patch,
PHOENIX-4287_v3_wip.patch
>
>
> With {{phoenix.use.stats.parallelization}} set to {{false}}, aggregate query returns
incorrect results when stats are available.
> With local index and stats disabled for parallelization:
> {noformat}
> explain select count(*) from TABLE_T;
> +-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+
> |                                                 PLAN                              
                   | EST_BYTES_READ  | EST_ROWS_READ  |  EST_INFO |
> +-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+
> | CLIENT 0-CHUNK 332170 ROWS 625043899 BYTES PARALLEL 0-WAY RANGE SCAN OVER TABLE_T [1]
 | 625043899       | 332170         | 150792825 |
> |     SERVER FILTER BY FIRST KEY ONLY                                               
                   | 625043899       | 332170         | 150792825 |
> |     SERVER AGGREGATE INTO SINGLE ROW                                              
                   | 625043899       | 332170         | 150792825 |
> +-------------------------------------------------------------------------------------------------------+-----------------+----------------+-----------+
> select count(*) from TABLE_T;
> +-----------+
> | COUNT(1)  |
> +-----------+
> | 0         |
> +-----------+
> {noformat}
> Using data table
> {noformat}
> explain select /*+NO_INDEX*/ count(*) from TABLE_T;
> +--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+
> |                                               PLAN                                
              | EST_BYTES_READ  | EST_ROWS_READ  |  EST_INFO_TS   |
> +--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+
> | CLIENT 2-CHUNK 332151 ROWS 438492470 BYTES PARALLEL 1-WAY FULL SCAN OVER TABLE_T  |
438492470       | 332151         | 1507928257617  |
> |     SERVER FILTER BY FIRST KEY ONLY                                               
              | 438492470       | 332151         | 1507928257617  |
> |     SERVER AGGREGATE INTO SINGLE ROW                                              
              | 438492470       | 332151         | 1507928257617  |
> +--------------------------------------------------------------------------------------------------+-----------------+----------------+----------------+
> select /*+NO_INDEX*/ count(*) from TABLE_T;
> +-----------+
> | COUNT(1)  |
> +-----------+
> | 14        |
> +-----------+
> {noformat}
> Without stats available, results are correct:
> {noformat}
> explain select /*+NO_INDEX*/ count(*) from TABLE_T;
> +----------------------------------------------------------------------+-----------------+----------------+--------------+
> |                                 PLAN                                 | EST_BYTES_READ
 | EST_ROWS_READ  | EST_INFO_TS  |
> +----------------------------------------------------------------------+-----------------+----------------+--------------+
> | CLIENT 2-CHUNK PARALLEL 1-WAY FULL SCAN OVER TABLE_T  | null            | null    
      | null         |
> |     SERVER FILTER BY FIRST KEY ONLY                                  | null       
    | null           | null         |
> |     SERVER AGGREGATE INTO SINGLE ROW                                 | null       
    | null           | null         |
> +----------------------------------------------------------------------+-----------------+----------------+--------------+
> select /*+NO_INDEX*/ count(*) from TABLE_T;
> +-----------+
> | COUNT(1)  |
> +-----------+
> | 333327    |
> +-----------+
> {noformat}



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