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Posted to issues@calcite.apache.org by "Nishant Bangarwa (JIRA)" <ji...@apache.org> on 2017/03/03 14:26:45 UTC
[jira] [Created] (CALCITE-1670) Count distinct on druid is
translated to Cardinality aggregator which is approximate
Nishant Bangarwa created CALCITE-1670:
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Summary: Count distinct on druid is translated to Cardinality aggregator which is approximate
Key: CALCITE-1670
URL: https://issues.apache.org/jira/browse/CALCITE-1670
Project: Calcite
Issue Type: Bug
Reporter: Nishant Bangarwa
Assignee: Julian Hyde
Right now count distinct on Druid is pushed as a 'cardinality' aggregator which uses hyperloglog and return approximate results. See cardinality aggregator here - http://druid.io/docs/latest/querying/aggregations.html for details.
https://github.com/apache/calcite/blob/master/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java#L721
{code}
case COUNT:
if (aggCall.isDistinct()) {
return new JsonCardinalityAggregation("cardinality", name, list);
}
return new JsonAggregation("count", name, only);
{code}
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