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https://issues.apache.org/jira/browse/HIVE-14353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15398540#comment-15398540
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Nemon Lou commented on HIVE-14353:
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The motivation of this jira ticket is that ,I found that query46 was lower with
CBO on than off, while the join order is the same. ( I changed the join order
in SQL manually when CBO is off.)
After comparing these two query plans,the major difference is the select
operator introduced by CBO's projection pruning.
> Performance degradation after Projection Pruning in CBO
> --------------------------------------------------------
>
> Key: HIVE-14353
> URL: https://issues.apache.org/jira/browse/HIVE-14353
> Project: Hive
> Issue Type: Bug
> Components: CBO, Logical Optimizer
> Affects Versions: 1.2.1
> Reporter: Nemon Lou
> Attachments: q46_cbo_no_projection_prune_explain.txt,
> q46_cbo_projection_prune_explain.rar
>
>
> TPC-DS with factor 1024.
> Hive on Spark.
> With and without projection prunning,time spent are quite different.
> The way to disable projection prunning : disable HiveRelFieldTrimmer in code
> and compile a new jar.
> ||queries||CBO_no_projection_prune||CBO||
> |q27| 160|251 |
> |q7 | 200|312 |
> |q88| 701|1092|
> |q68| 234|345 |
> |q39| 53|78 |
> |q73| 160|228 |
> |q31| 463|659 |
> |q79| 242|343 |
> |q46| 256|363 |
> |q60| 271|382 |
> |q66| 198|278 |
> |q34| 155|217 |
> |q19| 184|256 |
> |q26| 154|214 |
> |q56| 262|364 |
> |q75| 942|1303|
> |q71| 288|388 |
> |q25| 329|442 |
> |q52| 142|190 |
> |q42| 142|189 |
> |q3 | 139|185 |
> |q98| 153|203 |
> |q89| 187|248 |
> |q58| 264|340 |
> |q43| 127|162 |
> |q32| 174|221 |
> |q96| 156|197 |
> |q70| 320|404 |
> |q29| 499|629 |
> |q18| 266|329 |
> |q21| 76 |92 |
> |q90| 139|165 |
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