[jira] [Updated] (KUDU-2231) "materializing_iterator_do_pushdown=true" cause simple query slow

["Grant Henke (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KUDU-2231?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Grant Henke updated KUDU-2231:
------------------------------
    Fix Version/s: 1.6.1
                   1.5.1

> "materializing_iterator_do_pushdown=true" cause simple query slow
> -----------------------------------------------------------------
>
>                 Key: KUDU-2231
>                 URL: https://issues.apache.org/jira/browse/KUDU-2231
>             Project: Kudu
>          Issue Type: Bug
>          Components: master, tserver
>    Affects Versions: 1.4.0, 1.5.0, 1.6.0
>         Environment: CentOS release 6.5 (2.6.32-431.11.9.el6.ucloud.x86_64)
> KUDU-1.4.0-1.cdh5.12.1.p0.10
> IMPALA 2.6.0
> x86-64 
> Intel CPU
>            Reporter: DawnZhang
>            Assignee: Dan Burkert
>            Priority: Major
>             Fix For: 1.5.1, 1.7.0, 1.6.1
>
>         Attachments: 756ACA6F105F0905EBCB79B940FFCE86.jpg, F8C604537B8E921DDCCA78995DC11BDA.jpg, screenshot-1.png
>
>
> I ran the following SQL again and again
> while refresh 8050/scans page at the same time.
> sql:
> {code:sql}
> select count(xx_id),count(yy_id),count(time) from  test_table  where event_id =29983; 
> {code}
> "Cells read from disk"  is much more greater then table size when materializing_iterator_do_pushdown = true (default).
> after setting materializing_iterator_do_pushdown = false 
> "Cells read from disk" reduced to some reasonable value (close to table size)
> and the  sql run faster.
> here's detail:
> table under test:
> {code:sql}
> CREATE TABLE rawdata.test_table (
>   day INT NOT NULL ENCODING BIT_SHUFFLE COMPRESSION DEFAULT_COMPRESSION,
>   user_id BIGINT NOT NULL ENCODING BIT_SHUFFLE COMPRESSION DEFAULT_COMPRESSION,
>   time TIMESTAMP NOT NULL ENCODING BIT_SHUFFLE COMPRESSION DEFAULT_COMPRESSION,
>   event_id INT NULL ENCODING BIT_SHUFFLE COMPRESSION DEFAULT_COMPRESSION,
>   distinct_id STRING NULL ENCODING DICT_ENCODING COMPRESSION DEFAULT_COMPRESSION,
>   ...
>   ...  other fields ...
>   ...
>   PRIMARY KEY (day, user_id, time, _offset)
> )
> PARTITION BY HASH (user_id) PARTITIONS 9
> STORED AS KUDU
> TBLPROPERTIES ( ... );
> {code}
> table size (select count(1) from test_table) : 19510709
> CASE 1, materializing_iterator_do_pushdown = true
> [^756ACA6F105F0905EBCB79B940FFCE86.jpg]
> CASE 2, materializing_iterator_do_pushdown = false (sql ran faster)
> [^F8C604537B8E921DDCCA78995DC11BDA.jpg]
> it looks like kudu scan table multiple times for the simple sql caused by some silly bug.



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