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From "Victoria Markman (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (DRILL-2849) Difference in query results over CSV file created by CTAS, compared to results over original CSV file
Date Fri, 08 May 2015 22:40:05 GMT

     [ https://issues.apache.org/jira/browse/DRILL-2849?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Victoria Markman resolved DRILL-2849.
-------------------------------------
    Resolution: Fixed

> Difference in query results over CSV file created by CTAS, compared to results over original
CSV file 
> ------------------------------------------------------------------------------------------------------
>
>                 Key: DRILL-2849
>                 URL: https://issues.apache.org/jira/browse/DRILL-2849
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Storage - Text & CSV
>    Affects Versions: 0.9.0
>         Environment: 64e3ec52b93e9331aa5179e040eca19afece8317 | DRILL-2611: value vectors
should report valid value count | 16.04.2015 @ 13:53:34 EDT
>            Reporter: Khurram Faraaz
>            Assignee: Khurram Faraaz
>            Priority: Critical
>             Fix For: 1.0.0
>
>
> Different results are seen for the same query over CSV data file and another CSV data
file created by CTAS using the same CSV file.
> Tests were executed on 4 node cluster on CentOS.
> I got rid of the header information that is written by CTAS into the new CSV file that
CTAS creates, and then ran my queries over CTAS' CSV file.
> query over uncompressed CSV file, deletions/deletions-00000-of-00020.csv
> {code}
> > select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `deletions/deletions-00000-of-00020.csv`
group by columns[7];
> 88 rows selected (6.893 seconds)
> =================================================
> {code}
> query over CSV file that was created by CTAS. (input to CTAS was deletions/deletions-00000-of-00020.csv)
> Notice there is one more record returned.
> {code}
> > select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `csvToCSV_00000_of_00020/0_0_0.csv`
group by columns[7];
>  
> 89 rows selected (6.623 seconds)
> ==================================================
> {code}
> query over compressed CSV file
> {code}
> > select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `deletions-00000-of-00020.csv.gz`
group by columns[7];
> 88 rows selected (10.526 seconds)
> ==================================================
> {code}
> In the below cases, the count and sum results are different when query is executed over
CSV file that was created by CTAS. ( this may explain why we see the difference in results
in the above queries ? )
> {code}
> 0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `deletions/deletions-00000-of-00020.csv`
where columns[7] is null group by columns[7];
> +------------+------------+------------+------------+------------+
> |   EXPR$0   |   EXPR$1   |   EXPR$2   |   EXPR$3   |   EXPR$4   |
> +------------+------------+------------+------------+------------+
> | 252        | 1.362983396001E12 | 1.165768779027E12 | 1.293794515595635E12 | null  
    |
> +------------+------------+------------+------------+------------+
> 1 row selected (6.013 seconds)
> 0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `deletions-00000-of-00020.csv.gz`
where columns[7] is null group by columns[7];
> +------------+------------+------------+------------+------------+
> |   EXPR$0   |   EXPR$1   |   EXPR$2   |   EXPR$3   |   EXPR$4   |
> +------------+------------+------------+------------+------------+
> | 252        | 1.362983396001E12 | 1.165768779027E12 | 1.293794515595635E12 | null  
    |
> +------------+------------+------------+------------+------------+
> 1 row selected (8.899 seconds)
> {code}
> Notice that count and sum results are different (from those above) when query is executed
over the CSV file created by CTAS.
> {code}
> 0: jdbc:drill:> select count(cast(columns[0] as double)),max(cast(columns[0] as double)),min(cast(columns[0]
as double)),avg(cast(columns[0] as double)), columns[7] from `csvToCSV_00000_of_00020/0_0_0.csv`
where columns[7] is null group by columns[7];
> +------------+------------+------------+------------+------------+
> |   EXPR$0   |   EXPR$1   |   EXPR$2   |   EXPR$3   |   EXPR$4   |
> +------------+------------+------------+------------+------------+
> | 245        | 1.349670663E12 | 1.165768779027E12 | 1.2930281335065144E12 | null    
  |
> +------------+------------+------------+------------+------------+
> 1 row selected (5.736 seconds)
> {code}



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