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From "Ashish Sharma (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (HIVE-12898) Hive should support ORC block skipping on nested fields
Date Thu, 26 Apr 2018 11:59:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-12898?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ashish Sharma reassigned HIVE-12898:
------------------------------------

    Assignee: Ashish Sharma

> Hive should support ORC block skipping on nested fields
> -------------------------------------------------------
>
>                 Key: HIVE-12898
>                 URL: https://issues.apache.org/jira/browse/HIVE-12898
>             Project: Hive
>          Issue Type: Improvement
>          Components: ORC
>    Affects Versions: 0.14.0, 1.2.1
>            Reporter: Michael Haeusler
>            Assignee: Ashish Sharma
>            Priority: Major
>
> Hive supports predicate pushdown (block skipping) for ORC tables only on top-level fields.
Hive should also support block skipping on nested fields (within structs).
> Example top-level: the following query selects 0 rows, using a predicate on top-level
column foo. We also see 0 INPUT_RECORDS in the summary:
> {code:sql}
> SET hive.tez.exec.print.summary=true;
> CREATE TABLE t_toplevel STORED AS ORC AS SELECT 23 AS foo;
> SELECT * FROM t_toplevel WHERE foo=42 ORDER BY foo;
> [...]
> VERTICES         TOTAL_TASKS  FAILED_ATTEMPTS KILLED_TASKS DURATION_SECONDS    CPU_TIME_MILLIS
    GC_TIME_MILLIS  INPUT_RECORDS   OUTPUT_RECORDS
> Map 1                      1                0            0             1.22         
    2,640                102              0                0
> {code}
> Example nested: the following query also selects 0 rows, but using a predicate on nested
column foo.bar. Unfortunately we see 1 INPUT_RECORDS in the summary:
> {code:sql}
> SET hive.tez.exec.print.summary=true;
> CREATE TABLE t_nested STORED AS ORC AS SELECT NAMED_STRUCT('bar', 23) AS foo;
> SELECT * FROM t_nested WHERE foo.bar=42 ORDER BY foo;
> [...]
> VERTICES         TOTAL_TASKS  FAILED_ATTEMPTS KILLED_TASKS DURATION_SECONDS    CPU_TIME_MILLIS
    GC_TIME_MILLIS  INPUT_RECORDS   OUTPUT_RECORDS
> Map 1                      1                0            0             3.66         
    5,210                 68              1                0
> {code}



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