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Hive QA commented on HIVE-19586: -------------------------------- | (/) *{color:green}+1 overall{color}* | \\ \\ || Vote || Subsystem || Runtime || Comment || || || || || {color:brown} Prechecks {color} || | {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. {color} | | {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m 49s{color} | {color:green} master passed {color} | || || || || {color:brown} Patch Compile Tests {color} || | {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. {color} | | {color:black}{color} | {color:black} {color} | {color:black} 20m 49s{color} | {color:black} {color} | \\ \\ || 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? -- This message was sent by Atlassian JIRA (v7.6.3#76005)