[jira] [Commented] (DRILL-7450) Improve performance for ANALYZE command

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-7450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16981365#comment-16981365 ] 

ASF GitHub Bot commented on DRILL-7450:
---------------------------------------

vvysotskyi commented on pull request #1907: DRILL-7450: Improve performance for ANALYZE command
URL: https://github.com/apache/drill/pull/1907
 
 
   Jira - [DRILL-7450](https://issues.apache.org/jira/browse/DRILL-7450).
   
   This pull request contains several commits that may be reviewed one-by-one.
   The first commit "Improve performance for `ANALYZE` command" contains changes for two-phase metadata stream aggregation support. The main logic is placed in `MetadataAggPrule` - it converts the lowest `MetadataAggRel` into the following plan:
   
   ```
   MetadataAggPrel(PHASE_2of2)
     \
     HashToMergeExchangePrel
       \
       MetadataAggPrel(PHASE_1of2)
   ```
   
   Also, this commit introduces `ConvertMetadataAggregateToDirectScanRule` rule which replaces the lowest `MetadataAggRel` with `DrillDirectScanRel` populated from row groups metadata if required metadata is present:
   
   ```
   MetadataAggRel(metadataLevel=ROW_GROUP)
     \
     DrillScanRel
   ```
   
   is converted into
   
   ```
   DrillDirectScanRel
   ```
   
   The last commit contains changes to use hash aggregation for `PHASE_1of2` for `ANALYZE` to reduce memory usage and avoid sorting non-aggregated data.
 
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> Improve performance for ANALYZE command
> ---------------------------------------
>
>                 Key: DRILL-7450
>                 URL: https://issues.apache.org/jira/browse/DRILL-7450
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.17.0
>            Reporter: Vova Vysotskyi
>            Assignee: Vova Vysotskyi
>            Priority: Blocker
>             Fix For: 1.17.0
>
>
> In the scope of DRILL-7273 was introduced ANALYZE command for collecting metadata and storing it to the metastore.
> But current implementation uses too much memory and is low-performant. It uses stream aggregate for collecting metadata, but all incoming data should be sorted before producing the aggregation. Memory usage may be reduced by using hash aggregate, so sort may not be produced and it should increase performance.



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