[jira] [Comment Edited] (HIVE-17486) Enable SharedWorkOptimizer in tez on HOS
[
https://issues.apache.org/jira/browse/HIVE-17486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16308995#comment-16308995
]
liyunzhang edited comment on HIVE-17486 at 1/3/18 1:40 AM:
---
[~stakiar]:
the original purpose to change M->R to M->M->R is to let
CombineEquivalentWorkResolver combine same Maps. Like
logical plan
{code}
TS[0]-FIL[52]-SEL[2]-GBY[3]-RS[4]-GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
TS[1] -FIL[53]-SEL[9]-GBY[10]-RS[11]-GBY[12]-RS[43]-JOIN[48]
{code}
physical plan
{code}
Map1:TS[0]
Map2:TS[1]
Map3:FIL[52]-SEL[2]-GBY[3]-RS[4]
Map4:FIL[53]-SEL[9]-GBY[10]-RS[11]
Reducer1:GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
Reducer2:GBY[12]-RS[43]
{code}
For {{CombineEquivalentWorkResolver}}, it will combine same Maps. In above
case, Map2 will be removed because TS\[0\] is same as TS\[1\].
But when I finished the code, I found that there is no necessary to use this
way to combine TS\[0\] and TS\[1\]. {{MapInput}} is responsible for TS and I
only need generate same MapInput for TS\[0\] and TS\[1\]. More detail see
HIVE-17486.5.patch.
was (Author: kellyzly):
[~stakiar]:
the original purpose to change M->R to M->M->R is to let
CombineEquivalentWorkResolver combine same Maps. Like
logical plan
{code}
TS[0]-FIL[52]-SEL[2]-GBY[3]-RS[4]-GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
TS[1] -FIL[53]-SEL[9]-GBY[10]-RS[11]-GBY[12]-RS[43]-JOIN[48]
{code}
physical plan
{code}
Map1:TS[0]
Map2:TS[1]
Map3:FIL[52]-SEL[2]-GBY[3]-RS[4]
Map4:FIL[53]-SEL[9]-GBY[10]-RS[11]
Reducer1:GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
Reducer2:GBY[12]-RS[43]
{code}
For {{CombineEquivalentWorkResolver}}, it will combine same Maps. In above
case, Map2 will be removed because TS\[0\] is same as TS\[1\].
But when I finish the code, I found that there is no necessary to use this way
to combine TS\[0\] and TS\[1\]. {{MapInput}} is responsible for TS and I only
need generate same MapInput for TS\[0\] and TS\[1\]. More detail see
HIVE-17486.5.patch.
> Enable SharedWorkOptimizer in tez on HOS
>
>
> Key: HIVE-17486
> URL: https://issues.apache.org/jira/browse/HIVE-17486
> Project: Hive
> Issue Type: Bug
>Reporter: liyunzhang
>Assignee: liyunzhang
> Attachments: HIVE-17486.1.patch, HIVE-17486.2.patch,
> HIVE-17486.3.patch, HIVE-17486.4.patch, explain.28.share.false,
> explain.28.share.true, scanshare.after.svg, scanshare.before.svg
>
>
> in HIVE-16602, Implement shared scans with Tez.
> Given a query plan, the goal is to identify scans on input tables that can be
> merged so the data is read only once. Optimization will be carried out at the
> physical level. In Hive on Spark, it caches the result of spark work if the
> spark work is used by more than 1 child spark work. After sharedWorkOptimizer
> is enabled in physical plan in HoS, the identical table scans are merged to 1
> table scan. This result of table scan will be used by more 1 child spark
> work. Thus we need not do the same computation because of cache mechanism.
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[jira] [Comment Edited] (HIVE-17486) Enable SharedWorkOptimizer in tez on HOS
[ https://issues.apache.org/jira/browse/HIVE-17486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16292203#comment-16292203 ] liyunzhang edited comment on HIVE-17486 at 12/15/17 9:15 AM: - [~lirui] and [~xuefuz]: I have updated HIVE-17486.2.patch and designed again . A similar case like DS/query28.sql is run successfully. This proved that current design(M-M-R) can use RDD cache to reduce the table scan. In the latest design doc, there is a simple case. Currently, although i have added the simple case(spark_optimize_shared_work.q), there is some exception when running qtest in my local env. Once fix the problem, will trigger Hive QA to test. was (Author: kellyzly): [~lirui] and [~xuefuz]: I have updated HIVE-17486.2.patch and designed again because a similar case like DS/query28.sql is run successfully. This proved that current design(M-M-R) can use RDD cache to reduce the table scan. In the latest design doc, there is a simple case. Currently, although i have added the simple case(spark_optimize_shared_work.q), there is some exception when running qtest in my local env. Once fix the problem, will trigger Hive QA to test. > Enable SharedWorkOptimizer in tez on HOS > > > Key: HIVE-17486 > URL: https://issues.apache.org/jira/browse/HIVE-17486 > Project: Hive > Issue Type: Bug >Reporter: liyunzhang >Assignee: liyunzhang > Attachments: HIVE-17486.1.patch, HIVE-17486.2.patch, > explain.28.share.false, explain.28.share.true, scanshare.after.svg, > scanshare.before.svg > > > in HIVE-16602, Implement shared scans with Tez. > Given a query plan, the goal is to identify scans on input tables that can be > merged so the data is read only once. Optimization will be carried out at the > physical level. In Hive on Spark, it caches the result of spark work if the > spark work is used by more than 1 child spark work. After sharedWorkOptimizer > is enabled in physical plan in HoS, the identical table scans are merged to 1 > table scan. This result of table scan will be used by more 1 child spark > work. Thus we need not do the same computation because of cache mechanism. -- This message was sent by Atlassian JIRA (v6.4.14#64029)
[jira] [Comment Edited] (HIVE-17486) Enable SharedWorkOptimizer in tez on HOS
[
https://issues.apache.org/jira/browse/HIVE-17486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16285558#comment-16285558
]
liyunzhang edited comment on HIVE-17486 at 12/11/17 6:41 AM:
-
[~xuefuz]
{quote} It seems that we can do so whenever an TS is connected to multiple
RSs. The split point should happen at the fork. {quote} not very understand
about this. Currently the split is on the TS
for example
{code}
TS[0]-FIL[52]-SEL[2]-GBY[3]-RS[4]-GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
-FIL[53]-SEL[9]-GBY[10]-RS[11]-GBY[12]-RS[43]-JOIN[48]
{code}
->
{code}
Map1: TS[0]
Map2:FIL[52]-SEL[2]-GBY[3]-RS[4]
Map3:FIL[53]-SEL[9]-GBY[10]-RS[11]
Reducer1:GBY[5]-RS[42]-JOIN[48]-SEL[49]-LIM[50]-FS[51]
Reducer2:GBY[12]-RS[43]
{code}
was (Author: kellyzly):
[~xuefuz]
{quote} It seems that we can do so whenever an TS is connected to multiple
RSs. The split point should happen at the fork. {quote} not very understand
about this. Please explain more, thanks!
> Enable SharedWorkOptimizer in tez on HOS
>
>
> Key: HIVE-17486
> URL: https://issues.apache.org/jira/browse/HIVE-17486
> Project: Hive
> Issue Type: Bug
>Reporter: liyunzhang
>Assignee: liyunzhang
> Attachments: HIVE-17486.1.patch, explain.28.share.false,
> explain.28.share.true, scanshare.after.svg, scanshare.before.svg
>
>
> in HIVE-16602, Implement shared scans with Tez.
> Given a query plan, the goal is to identify scans on input tables that can be
> merged so the data is read only once. Optimization will be carried out at the
> physical level. In Hive on Spark, it caches the result of spark work if the
> spark work is used by more than 1 child spark work. After sharedWorkOptimizer
> is enabled in physical plan in HoS, the identical table scans are merged to 1
> table scan. This result of table scan will be used by more 1 child spark
> work. Thus we need not do the same computation because of cache mechanism.
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This message was sent by Atlassian JIRA
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[jira] [Comment Edited] (HIVE-17486) Enable SharedWorkOptimizer in tez on HOS
[
https://issues.apache.org/jira/browse/HIVE-17486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16235125#comment-16235125
]
liyunzhang edited comment on HIVE-17486 at 11/2/17 3:35 AM:
[~lirui]:
{quote}
My understanding is HoS also supports one Map connecting to multiple Reducers
{quote}
There is only 1 RS in Map in HoS. It is true that there are cases that 1 Map is
used by two Reducers in HoS. But in HoT, 2 RS are allowed in 1 Map, the
different 2 RS in the 1 Map can transfer different data to 2 different
Reducers.
{quote}
The problem here is HoS doesn't merge equivalent works as aggressively as HoT
does.
{quote}
yes
was (Author: kellyzly):
[~lirui]:
{quote}
My understanding is HoS also supports one Map connecting to multiple Reducers
{quote}
There is only 1 RS in Map in HoS. It is true that there are cases that 1 Map is
used by two Reducers in HoS. But in HoT, 2 RS are allowed in 1 Map, the
different 2 RS in the 1 Map can transfer different data to 2 different
Reducers.
> Enable SharedWorkOptimizer in tez on HOS
>
>
> Key: HIVE-17486
> URL: https://issues.apache.org/jira/browse/HIVE-17486
> Project: Hive
> Issue Type: Bug
>Reporter: liyunzhang
>Assignee: liyunzhang
>Priority: Major
> Attachments: scanshare.after.svg, scanshare.before.svg
>
>
> in HIVE-16602, Implement shared scans with Tez.
> Given a query plan, the goal is to identify scans on input tables that can be
> merged so the data is read only once. Optimization will be carried out at the
> physical level. In Hive on Spark, it caches the result of spark work if the
> spark work is used by more than 1 child spark work. After sharedWorkOptimizer
> is enabled in physical plan in HoS, the identical table scans are merged to 1
> table scan. This result of table scan will be used by more 1 child spark
> work. Thus we need not do the same computation because of cache mechanism.
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