[jira] [Commented] (HIVE-9153) Evaluate CombineHiveInputFormat versus HiveInputFormat [Spark Branch]

["Rui Li (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-9153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14251407#comment-14251407 ] 

Rui Li commented on HIVE-9153:
------------------------------

I used our cluster B to test this. Results show that CombineHiveInputFormat still performs much better than HiveInputFormat for spark. The test query is {code}select count(*) from store_sales where ss_sold_date_sk is not null;{code}
With CombineHiveInputFormat spark spawns 1252 mappers and the query finishes in about 180s, while HiveInputFormat requires 13559 mappers and the query finishes in about 700s.
I didn't find why Tez uses HiveInputFormat as default. But for Tez, HiveInputFormat spawns 332 mappers while CombineHiveInputFormat spawns 1252. So I think Tez has its own way to combine the splits. With 332 mappers, Tez finishes the query in about 90s, and with 1252 mappers, it took about 120s.

> Evaluate CombineHiveInputFormat versus HiveInputFormat [Spark Branch]
> ---------------------------------------------------------------------
>
>                 Key: HIVE-9153
>                 URL: https://issues.apache.org/jira/browse/HIVE-9153
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Spark
>    Affects Versions: spark-branch
>            Reporter: Brock Noland
>            Assignee: Rui Li
>
> The default InputFormat is {{CombineHiveInputFormat}} and thus HOS uses this. However, Tez uses {{HiveInputFormat}}. Since tasks are relatively cheap in Spark, it might make sense for us to use {{HiveInputFormat}} as well. We should evaluate this on a query which has many input splits such as {{select count(\*) from store_sales where something is not null}}.



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