[GitHub] [druid] xiangqiao123 commented on issue #9689: groupBy query: limit push down to segment scan is poor performance

[GitBox <gi...@apache.org>]

xiangqiao123 commented on issue #9689: groupBy query: limit push down to segment scan is poor performance
URL: https://github.com/apache/druid/issues/9689#issuecomment-613267976
 
 
   > Thanks for the report @xiangqiao123 , do you have any additional details on the query you issued, such as what the limit was, any extractionFn or lookups, and any details about segment size, column type, if string approximate cardinality, or anything else you think might be useful in helping us determine why the performance degraded?
   
   1. Query statement：
   {
       "dimensions": [
           "host",
           "type",
           "status"
       ],
       "aggregations": [
           {
               "type": "longSum",
               "fieldName": "__count__",
               "name": "SUM(__count__)"
           }
       ],
       "intervals": "2020-04-08T00:00:00+08:00/2020-04-09T00:00:00+08:00",
       "limitSpec": {
           "type": "default",
           "limit": 50000,
           "columns": []
       },
       "granularity": {
           "type": "period",
           "period": "PT1M",
           "timeZone": "Asia/Shanghai",
           "origin": "1970-01-01T00:00:00+08:00"
       },
       "queryType": "groupBy",
       "dataSource": "druid_ds",
       "context": {
           "useCache": false,
           "populateCache": false,
       }
   }
   2.This is about 50 segments，1G  per segment

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