Hive LLAP
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LLAP是hive 2.0.0版本引入的新特性，hive官方称为(Live long and process)，hortonworks公司的CDH称为(low-latency analytical processing)，其实它们都是一样的，都是实现将数据预取、缓存到基于yarn运行的守护进程中，降低和减少系统IO和与HDFS DataNode的交互，具体的特性细节参考官方文档 Hive llap (如果链接未生效，在文章后面的链接中获取)，但是由于版本更新频繁和官方文档的维护不力因素，很多地方和使用上让人概念不清、正确和错误分不清，特别是用CDH这样的集成套件，很多细节被忽略，本文一一来细说和总结各类问题。
1 hive llap该怎么部署
分两种情况： 1. 如果使用的hadoop yarn版本是3.1.0以下(不包含3.1.0)，需要使用 Apache slider 来部署，因为在hadoop yarn 3.1.0之前，yarn本身不支持长时间运行的服务(long running services)，而slider组件是可以打包、管理和部署长时间运行的服务到yarn上运行的。 2. 如果使用的hadoop yarn版本是3.1.0及以上，完全不需要slider组件了，因为从 hadoop yarn 3.1.0 开始，yarn已经合并支持long running services了，slider项目也停止更新了。
因此，部署时要考虑使用的组件版本，再确定部署方案，对于开源项目，使用的版本和环境很重要，如果组件本身已经提供特性和功能，并且一直处于维护状态，建议尽量不要使用其它组件替代，替代成本和异常问题远比想象的高。
当然，如果你使用的是CDH类的集成套件，套件本身已经集成封装，每个套件版本会提供相应的支持，这些内容就无需多虑了。
2 注意事项
- llap 目前只支持tez引擎，需要先部署好hive和tez；
- 由于llap依赖zookeeper和hadoop组件，如果集群开启了安全认证(比如kerberos)，llap也要进行安全认证相关配置，使用到的配置参数如：
<property>
<name>hive.llap.daemon.keytab.file</name>
<value>/etc/security/keytabs/demo.keytab</value>
</property>
<property>
<name>hive.llap.daemon.service.principal</name>
<value>demo/sywu@sywukeb</value>
</property>
<property>
<name>hive.llap.task.scheduler.am.registry.keytab.file</name>
<value>/etc/security/keytabs/demo.service.keytab</value>
</property>
<property>
<name>hive.llap.task.scheduler.am.registry.principal</name>
<value>demo/sywu@sywukeb</value>
</property>
另外随着程序的更新，官方文档上的参数参差不齐，有些参数需要阅读和从代码中查找。
- 一些网上资料和CDH文档的部署方式使用hive用户和权限运行llap服务，hive的权限很大，如果集群很大，使用的人很多，对权限控制粒度要求高，不适合使用这种方式，应该考虑多个llap服务，为不同的用户或者项目组开放不同的llap服务。
- 由于LLAP所具有的优势(预取、缓存)，对于大的集群，考虑面向不同场景和用户使用不同的llap服务，提高查询命中率，提升性能，我认为是合理的。
3 llap初始化
以下以hadoop 3.1.0，hive 3.1.0，tez 0.9.1，集群无安全认证为例，首先配置llap；
<property>
<name>hive.llap.execution.mode</name>
<value>all</value>
</property>
<property>
<name>hive.execution.mode</name>
<value>llap</value>
</property>
<property>
<name>hive.llap.daemon.service.hosts</name>
<value>@sywu-llap01</value>
</property>
<property>
<name>hive.llap.daemon.memory.per.instance.mb</name>
<value>25600</value>
</property>
<property>
<name>hive.llap.daemon.num.executors</name>
<value>8</value>
</property>
<property>
<name>hive.llap.zk.sm.connectionString</name>
<value>sywu01:2181</value>
</property>
<property>
<name>hive.llap.zk.registry.namespace</name>
<value>hive_sywu01</value>
</property>
<property>
<name>hive.llap.zk.registry.user</name>
<value>sywu</value>
</property>
hive.llap.daemon.service.hosts 配置llap 实例名称，这个名称和启动的名称相同。然后打包和准备部署llap 服务的文件；
hive --service llap --name sywu-llap01 --instances 4 --size 60g --loglevel info --cache 30g --executors 10 --iothreads 10 --args " -XX:+UseG1GC -XX:+ResizeTLAB -XX:+UseNUMA -XX:-ResizePLAB"
这个命令会在当前目录生成llap 服务文件夹，里面包含启动llap的脚本，llap的相关配置和jar包；
$ ll
total 184M
-rwxr-xr-x 1 sywu01 sywu01 184M Oct 20 15:28 llap-20Oct2020.tar.gz
-rwxr-xr-x 1 sywu01 sywu01 273 Oct 20 15:28 run.sh
-rwxr-xr-x 1 sywu01 sywu01 2.0K Oct 20 15:29 Yarnfile
执行run.sh 文件启动llap服务。到此llap部署到yarn上并运行。
LLAPSTATUS
--------------------------------------------------------------------------------
LLAP Application running with ApplicationId=application_1602234006497_0592
--------------------------------------------------------------------------------
LLAP Application running with ApplicationId=application_1602234006497_0592
--------------------------------------------------------------------------------
{
"amInfo" : {
"appName" : "sywu-llap01",
"appType" : "yarn-service",
"appId" : "application_1602234006497_0592"
},
"state" : "RUNNING_ALL",
"desiredInstances" : 4,
"liveInstances" : 4,
"launchingInstances" : 0,
"appStartTime" : 0,
"runningThresholdAchieved" : false,
"runningInstances" : [ {
"hostname" : "sywu01",
"containerId" : "container_e48_1602234006497_0592_01_000013",
"statusUrl" : "http://sywu01:15002/status",
"webUrl" : "http://sywu01:15002",
"rpcPort" : 45795,
"mgmtPort" : 15004,
"shufflePort" : 15551,
"yarnContainerExitStatus" : 0
}, {
"hostname" : "sywu02",
"containerId" : "container_e48_1602234006497_0592_01_000005",
"statusUrl" : "http://sywu02:15002/status",
"webUrl" : "http://sywu02:15002",
"rpcPort" : 46845,
"mgmtPort" : 15004,
"shufflePort" : 15551,
"yarnContainerExitStatus" : 0
}, {
"hostname" : "sywu01",
"containerId" : "container_e48_1602234006497_0592_01_000008",
"statusUrl" : "http://sywu01:15002/status",
"webUrl" : "http://sywu01:15002",
"rpcPort" : 33382,
"mgmtPort" : 15004,
"shufflePort" : 15551,
"yarnContainerExitStatus" : 0
}, {
"hostname" : "sywu03",
"containerId" : "container_e48_1602234006497_0592_01_000010",
"statusUrl" : "http://sywu03:15002/status",
"webUrl" : "http://sywu03:15002",
"rpcPort" : 43520,
"mgmtPort" : 15004,
"shufflePort" : 15551,
"yarnContainerExitStatus" : 0
} ]
}
4 性能测试
到此，hive已经有mr和tez引擎，并支持llap，使用hortonworks公司开源的 hive-testbench项目 生成1Tb数据；
$ ./tpcds-setup.sh 1000
用query10.sql 中的关联脚本查询测试；
select
cd_gender,cd_marital_status,cd_education_status,count(*) cnt1,cd_purchase_estimate,count(*) cnt2,cd_credit_rating,count(*) cnt3,cd_dep_count,count(*) cnt4,cd_dep_employed_count,count(*) cnt5,cd_dep_college_count,count(*) cnt6
from
customer c,customer_address ca,customer_demographics
where
c.c_current_addr_sk = ca.ca_address_sk and
ca_county in ('Fillmore County','McPherson County','Bonneville County','Boone County','Brown County') and
cd_demo_sk = c.c_current_cdemo_sk and
exists (select *
from store_sales,date_dim
where c.c_customer_sk = ss_customer_sk and
ss_sold_date_sk = d_date_sk and
d_year = 2000 and
d_moy between 3 and 3+3) and
(exists (select *
from web_sales,date_dim
where c.c_customer_sk = ws_bill_customer_sk and
ws_sold_date_sk = d_date_sk and
d_year = 2000 and
d_moy between 3 ANd 3+3) or
exists (select *
from catalog_sales,date_dim
where c.c_customer_sk = cs_ship_customer_sk and
cs_sold_date_sk = d_date_sk and
d_year = 2000 and
d_moy between 3 and 3+3))
group by cd_gender,
cd_marital_status,
cd_education_status,
cd_purchase_estimate,
cd_credit_rating,
cd_dep_count,
cd_dep_employed_count,
cd_dep_college_count
order by cd_gender,
cd_marital_status,
cd_education_status,
cd_purchase_estimate,
cd_credit_rating,
cd_dep_count,
cd_dep_employed_count,
cd_dep_college_count
limit 100;
mr 引擎执行情况；
INFO : Query ID = sywu01_20201023113411_add04434-7382-4376-8883-26ab298b1c6f
INFO : Total jobs = 8
INFO : Starting task [Stage-24:MAPREDLOCAL] in parallel
INFO : Starting task [Stage-25:MAPREDLOCAL] in parallel
INFO : Starting task [Stage-26:MAPREDLOCAL] in parallel
INFO : Starting task [Stage-27:MAPREDLOCAL] in parallel
INFO : Launching Job 1 out of 8
INFO : Starting task [Stage-20:MAPRED] in parallel
INFO : Launching Job 2 out of 8
INFO : Starting task [Stage-14:MAPRED] in parallel
INFO : Launching Job 3 out of 8
INFO : Starting task [Stage-11:MAPRED] in parallel
INFO : Launching Job 4 out of 8
INFO : Starting task [Stage-18:MAPRED] in parallel
INFO : Starting task [Stage-17:CONDITIONAL] in parallel
INFO : Launching Job 5 out of 8
INFO : Starting task [Stage-3:MAPRED] in parallel
INFO : Launching Job 6 out of 8
INFO : Starting task [Stage-4:MAPRED] in parallel
INFO : Launching Job 7 out of 8
INFO : Starting task [Stage-5:MAPRED] in parallel
INFO : MapReduce Jobs Launched:
INFO : Stage-Stage-18: Map: 3 Cumulative CPU: 779.28 sec HDFS Read: 77140427 HDFS Write: 5298244 SUCCESS
INFO : Stage-Stage-20: Map: 350 Cumulative CPU: 4134.07 sec HDFS Read: 3203667384 HDFS Write: 193140638 SUCCESS
INFO : Stage-Stage-11: Map: 153 Reduce: 151 Cumulative CPU: 4631.57 sec HDFS Read: 886558268 HDFS Write: 46326191 SUCCESS
INFO : Stage-Stage-14: Map: 257 Reduce: 271 Cumulative CPU: 6646.95 sec HDFS Read: 1049371661 HDFS Write: 106287345 SUCCESS
INFO : Stage-Stage-3: Map: 19 Reduce: 2 Cumulative CPU: 394.45 sec HDFS Read: 351370942 HDFS Write: 1399528 SUCCESS
INFO : Stage-Stage-4: Map: 2 Reduce: 1 Cumulative CPU: 15.71 sec HDFS Read: 1415039 HDFS Write: 12296 SUCCESS
INFO : Stage-Stage-5: Map: 1 Reduce: 1 Cumulative CPU: 8.31 sec HDFS Read: 23606 HDFS Write: 7168 SUCCESS
INFO : Total MapReduce CPU Time Spent: 0 days 4 hours 36 minutes 50 seconds 340 msec
INFO : Completed executing command(queryId=sywu01_20201023113411_add04434-7382-4376-8883-26ab298b1c6f); Time taken: 838.106 seconds
INFO : OK
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| cd_gender | cd_marital_status | cd_education_status | cnt1 | cd_purchase_estimate | cnt2 | cd_credit_rating | cnt3 | cd_dep_count | cnt4 | cd_dep_employed_count | cnt5 | cd_dep_college_count | cnt6 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 0 | 1 | 0 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 0 | 1 | 5 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
....
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 0 | 1 | 4 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 3 | 1 | 2 | 1 | 1 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 4 | 1 | 0 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 6 | 1 | 6 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | Low Risk | 1 | 0 | 1 | 3 | 1 | 4 | 1 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
100 rows selected (850.686 seconds)
tez 引擎执行情况；
INFO : Query ID = sywu01_20201023175253_265d5780-7be4-47ad-ad4b-ef8154bb3842
INFO : Total jobs = 1
INFO : Launching Job 1 out of 1
INFO : Starting task [Stage-1:MAPRED] in parallel
----------------------------------------------------------------------------------------------
VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING FAILED KILLED
----------------------------------------------------------------------------------------------
Map 6 .......... container SUCCEEDED 14 14 0 0 0 10
Map 7 .......... container SUCCEEDED 4 4 0 0 3 3
Map 1 .......... container SUCCEEDED 6 6 0 0 0 1
Map 9 .......... container SUCCEEDED 1 1 0 0 0 1
Reducer 5 ...... container SUCCEEDED 1 1 0 0 0 1
Map 8 .......... container SUCCEEDED 20 20 0 0 0 0
Map 10 ......... container SUCCEEDED 6 6 0 0 0 0
Reducer 11 ..... container SUCCEEDED 234 234 0 0 0 0
Map 12 ......... container SUCCEEDED 10 10 0 0 0 0
Reducer 13 ..... container SUCCEEDED 234 234 0 0 0 0
Reducer 2 ...... container SUCCEEDED 234 234 0 0 0 0
Reducer 3 ...... container SUCCEEDED 145 145 0 0 0 0
Reducer 4 ...... container SUCCEEDED 1 1 0 0 0 0
----------------------------------------------------------------------------------------------
VERTICES: 13/13 [==========================>>] 100% ELAPSED TIME: 36.01 s
----------------------------------------------------------------------------------------------
INFO : Completed executing command(queryId=sywu01_20201023175253_265d5780-7be4-47ad-ad4b-ef8154bb3842); Time taken: 54.039 seconds
INFO : OK
- Query Execution Summary
- ----------------------------------------------------------------------------------------------
- OPERATION DURATION
- ----------------------------------------------------------------------------------------------
- Compile Query 0.00s
- Prepare Plan 0.00s
- Get Query Coordinator (AM) 0.00s
- Submit Plan 1603446798.35s
- Start DAG 1.05s
- Run DAG 34.93s
- ----------------------------------------------------------------------------------------------
-
- Task Execution Summary
- ----------------------------------------------------------------------------------------------
- VERTICES DURATION(ms) CPU_TIME(ms) GC_TIME(ms) INPUT_RECORDS OUTPUT_RECORDS
- ----------------------------------------------------------------------------------------------
- Map 1 16546.00 130,790 1,748 13,963,497 82,778
- Map 10 4568.00 49,540 484 27,755,681 15,784
- Map 12 3554.00 75,240 987 55,261,069 41,887
- Map 6 14520.00 131,700 5,584 6,000,000 42,697
- Map 7 13490.00 34,760 780 1,920,800 1,920,800
- Map 8 4073.00 80,900 472 106,067,119 73,854
- Map 9 3146.00 10,200 375 10,000 366
- Reducer 11 1531.00 27,450 623 15,784 157,859
- Reducer 13 1026.00 32,250 697 41,887 261,474
- Reducer 2 4577.00 267,060 4,652 575,965 22,170
- Reducer 3 4046.00 263,850 5,876 22,170 61,923
- Reducer 4 503.00 1,430 20 61,923 0
- Reducer 5 12877.00 2,360 0 82,778 3
- ----------------------------------------------------------------------------------------------
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| cd_gender | cd_marital_status | cd_education_status | cnt1 | cd_purchase_estimate | cnt2 | cd_credit_rating | cnt3 | cd_dep_count | cnt4 | cd_dep_employed_count | cnt5 | cd_dep_college_count | cnt6 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 0 | 1 | 0 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 0 | 1 | 5 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
....
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 0 | 1 | 4 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 3 | 1 | 2 | 1 | 1 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 4 | 1 | 0 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 6 | 1 | 6 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | Low Risk | 1 | 0 | 1 | 3 | 1 | 4 | 1 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
100 rows selected (61.765 seconds)
tez引擎 + llap 执行情况；
INFO : Query ID = sywu01_20201023174916_f4c7d891-7395-4720-9eb1-5bf1fd7c024c
INFO : Total jobs = 1
INFO : Launching Job 1 out of 1
INFO : Starting task [Stage-1:MAPRED] in parallel
----------------------------------------------------------------------------------------------
VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING FAILED KILLED
----------------------------------------------------------------------------------------------
Map 6 .......... llap SUCCEEDED 3 3 0 0 0 0
Map 7 .......... llap SUCCEEDED 4 4 0 0 0 0
Map 1 .......... llap SUCCEEDED 6 6 0 0 0 0
Map 9 .......... llap SUCCEEDED 1 1 0 0 0 0
Reducer 5 ...... llap SUCCEEDED 1 1 0 0 0 0
Map 8 .......... llap SUCCEEDED 6 6 0 0 0 0
Map 10 ......... llap SUCCEEDED 6 6 0 0 0 0
Reducer 11 ..... llap SUCCEEDED 234 234 0 0 0 0
Map 12 ......... llap SUCCEEDED 7 7 0 0 0 0
Reducer 13 ..... llap SUCCEEDED 234 234 0 0 0 0
Reducer 2 ...... llap SUCCEEDED 234 234 0 0 0 2
Reducer 3 ...... llap SUCCEEDED 145 145 0 0 0 3
Reducer 4 ...... llap SUCCEEDED 1 1 0 0 0 0
----------------------------------------------------------------------------------------------
VERTICES: 13/13 [==========================>>] 100% ELAPSED TIME: 11.34 s
----------------------------------------------------------------------------------------------
INFO : Completed executing command(queryId=sywu01_20201023174916_f4c7d891-7395-4720-9eb1-5bf1fd7c024c); Time taken: 30.035 seconds
INFO : OK
- Query Execution Summary
- ----------------------------------------------------------------------------------------------
- OPERATION DURATION
- ----------------------------------------------------------------------------------------------
- Compile Query 0.00s
- Prepare Plan 0.00s
- Get Query Coordinator (AM) 0.00s
- Submit Plan 1603446581.98s
- Start DAG 1.00s
- Run DAG 11.02s
- ----------------------------------------------------------------------------------------------
-
- Task Execution Summary
- ----------------------------------------------------------------------------------------------
- VERTICES DURATION(ms) CPU_TIME(ms) GC_TIME(ms) INPUT_RECORDS OUTPUT_RECORDS
- ----------------------------------------------------------------------------------------------
- Map 1 2042.00 0 0 13,963,497 82,778
- Map 10 1527.00 0 0 27,755,681 15,767
- Map 12 1530.00 0 0 55,261,069 40,935
- Map 6 514.00 0 0 6,000,000 42,697
- Map 7 514.00 0 0 1,920,800 1,920,800
- Map 8 3063.00 0 0 106,067,119 59,399
- Map 9 0.00 0 0 10,000 366
- Reducer 11 1536.00 0 0 15,767 14,579
- Reducer 13 1019.00 0 0 40,935 33,694
- Reducer 2 3059.00 0 0 190,450 22,170
- Reducer 3 2540.00 0 0 22,170 14,423
- Reducer 4 278.00 0 0 14,423 0
- Reducer 5 2041.00 0 0 82,778 3
- ----------------------------------------------------------------------------------------------
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| cd_gender | cd_marital_status | cd_education_status | cnt1 | cd_purchase_estimate | cnt2 | cd_credit_rating | cnt3 | cd_dep_count | cnt4 | cd_dep_employed_count | cnt5 | cd_dep_college_count | cnt6 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 0 | 1 | 0 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 0 | 1 | 5 | 1 |
| F | D | 2 yr Degree | 1 | 500 | 1 | Good | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
....
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 0 | 1 | 4 | 1 | 4 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 3 | 1 | 2 | 1 | 1 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 4 | 1 | 0 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | High Risk | 1 | 5 | 1 | 6 | 1 | 6 | 1 |
| F | D | 2 yr Degree | 1 | 3500 | 1 | Low Risk | 1 | 0 | 1 | 3 | 1 | 4 | 1 |
+------------+--------------------+-----------------------+-------+-----------------------+-------+-------------------+-------+---------------+-------+------------------------+-------+-----------------------+-------+
100 rows selected (37.668 seconds)
5 总结
可以看到，mr引擎的执行耗时(850.686 seconds)是tez引擎执行耗时(61.765 seconds)和tez引擎+llap执行耗时(37.668 seconds)的近14倍，资源使用率远远高于后者；tez引擎和tez引擎+llap确实极大的提升了查询性能，也让hive更越进一步，而这一切的代价，仅是对架构、底层的了解和认识以及组件的升级和更新能够获得的。
链接
- https://cwiki.apache.org/confluence/display/Hive/LLAP - Hive llap
- https://issues.apache.org/jira/browse/YARN-4692 - Simplified and first-class support for services in YARN
- http://hadoop.apache.org/docs/r3.1.0 - Apache Hadoop 3.1.0
- http://incubator.apache.org/projects/slider.html - Apache slider
- https://issues.apache.org/jira/browse/HIVE-9850 - documentation for llap
- https://issues.apache.org/jira/browse/HIVE-7926 - long-lived daemons for query fragment execution, I/O and caching
- https://github.com/hortonworks/hive-testbench - A testbench for experimenting with Apache Hive at any data scale.
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