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https://issues.apache.org/jira/browse/HIVE-16600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16002260#comment-16002260
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liyunzhang_intel commented on HIVE-16600:
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[~lirui]: thanks for review.
bq.I remember you mentioned there was something wrong when you first enable
parallel order by for multi insert. Have you figured out what was the cause?
{code}
set hive.exec.reducers.bytes.per.reducer=256;
set hive.optimize.sampling.orderby=true;
set hive.execution.engine=spark;
drop table if exists e1;
drop table if exists e2;
create table e1 (key string, keyD double);
create table e2 (key string, keyD double, value string);
FROM (select key, cast(key as double) as keyD, value from src order by key) a
INSERT OVERWRITE TABLE e1
SELECT key, COUNT(distinct value) group by key
INSERT OVERWRITE TABLE e2
SELECT key, sum(keyD), value group by key, value;
select * from e1;
select * from e2;
{code}
what i was confused last week is
the result of e1 and e2 is not order by the key when we set
hive.exec.reducers.bytes.per.reducer=256( this makes the parallel order by).
But forget my confuse because the result of e1 and e2 should not be in order
because this is a orderby+groupby case, the result of groupby may not be in
order.
> Refactor SetSparkReducerParallelism#needSetParallelism to enable parallel
> order by in multi_insert cases
> --------------------------------------------------------------------------------------------------------
>
> Key: HIVE-16600
> URL: https://issues.apache.org/jira/browse/HIVE-16600
> Project: Hive
> Issue Type: Sub-task
> Reporter: liyunzhang_intel
> Assignee: liyunzhang_intel
> Attachments: HIVE-16600.1.patch
>
>
> multi_insert_gby.case.q
> {code}
> set hive.exec.reducers.bytes.per.reducer=256;
> set hive.optimize.sampling.orderby=true;
> drop table if exists e1;
> drop table if exists e2;
> create table e1 (key string, value string);
> create table e2 (key string);
> FROM (select key, cast(key as double) as keyD, value from src order by key) a
> INSERT OVERWRITE TABLE e1
> SELECT key, value
> INSERT OVERWRITE TABLE e2
> SELECT key;
> select * from e1;
> select * from e2;
> {code}
> the parallelism of Sort is 1 even we enable parallel order
> by("hive.optimize.sampling.orderby" is set as "true"). This is not
> reasonable because the parallelism should be calcuated by
> [Utilities.estimateReducers|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/spark/SetSparkReducerParallelism.java#L170]
> this is because SetSparkReducerParallelism#needSetParallelism returns false
> when [children size of
> RS|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/spark/SetSparkReducerParallelism.java#L207]
> is greater than 1.
> in this case, the children size of {{RS[2]}} is two.
> the logical plan of the case
> {code}
> TS[0]-SEL[1]-RS[2]-SEL[3]-SEL[4]-FS[5]
> -SEL[6]-FS[7]
> {code}
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