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https://issues.apache.org/jira/browse/HIVE-19586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16499329#comment-16499329
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Hive QA commented on HIVE-19586:
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| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m
0s{color} | {color:green} The patch does not contain any @author tags. {color} |
|| || || || {color:brown} master Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 7m
2s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m
58s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m
34s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 3m
32s{color} | {color:blue} ql in master has 2278 extant Findbugs warnings.
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| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
49s{color} | {color:green} master passed {color} |
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| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m
14s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m
53s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 0m
53s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m
35s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m
0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 3m
42s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
51s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m
11s{color} | {color:green} The patch does not generate ASF License warnings.
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| {color:black}{color} | {color:black} {color} | {color:black} 20m 49s{color} |
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|| Subsystem || Report/Notes ||
| Optional Tests | asflicense javac javadoc findbugs checkstyle compile |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian
3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux |
| Build tool | maven |
| Personality |
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-11465/dev-support/hive-personality.sh
|
| git revision | master / 3bccc4e |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| modules | C: ql U: ql |
| Console output |
http://104.198.109.242/logs//PreCommit-HIVE-Build-11465/yetus.txt |
| Powered by | Apache Yetus http://yetus.apache.org |
This message was automatically generated.
> Optimize Count(distinct X) pushdown based on the storage capabilities
> ----------------------------------------------------------------------
>
> Key: HIVE-19586
> URL: https://issues.apache.org/jira/browse/HIVE-19586
> Project: Hive
> Issue Type: Improvement
> Components: Druid integration, Logical Optimizer
> Reporter: slim bouguerra
> Assignee: slim bouguerra
> Priority: Major
> Attachments: HIVE-19586.2.patch, HIVE-19586.3.patch,
> HIVE-19586.3.patch, HIVE-19586.4.patch, HIVE-19586.5.patch,
> HIVE-19586.6.patch, HIVE-19586.patch
>
>
> h1. Goal
> Provide a way to rewrite queries with combination of COUNT(Distinct) and
> Aggregates like SUM as a series of Group By.
> This can be useful to push down to Druid queries like
> {code}
> select count(DISTINCT interval_marker), count (distinct dim), sum(num_l)
> FROM druid_test_table GROUP BY `__time`, `zone` ;
> {code}
> In general this can be useful to be used in cases where storage handlers can
> not perform count (distinct column)
> h1. How to do it.
> Use the Calcite rule {code}
> org.apache.calcite.rel.rules.AggregateExpandDistinctAggregatesRule{code} that
> breaks down Count distinct to a single Group by with Grouping sets or
> multiple series of Group by that might be linked with Joins if multiple
> counts are present.
> FYI today Hive does have a similar rule {code}
> org.apache.hadoop.hive.ql.optimizer.calcite.rules.HiveExpandDistinctAggregatesRule{code},
> but it only provides a rewrite to Grouping sets based plan.
> I am planing to use the actual Calcite rule, [~ashutoshc] any concerns or
> caveats to be aware of?
> h2. Concerns/questions
> Need to have a way to switch between Grouping sets or Simple chained group by
> based on the plan cost. For instance for Druid based scan it makes always
> sense (at least today) to push down a series of Group by and stitch result
> sets in Hive later (as oppose to scan everything).
> But this might be not true for other storage handler that can handle Grouping
> sets it is better to push down the Grouping sets as one table scan.
> Am still unsure how i can lean on the cost optimizer to select the best plan,
> [~ashutoshc]/[~jcamachorodriguez] any inputs?
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