Stamatis Zampetakis created CALCITE-4204:
--------------------------------------------
Summary: Intermittent precision in Druid results when using
aggregation functions over columns of type DOUBLE
Key: CALCITE-4204
URL: https://issues.apache.org/jira/browse/CALCITE-4204
Project: Calcite
Issue Type: Bug
Components: druid-adapter
Environment: The results were obtained by using a dockerized Druid at
0.17.1: [https://github.com/zabetak/calcite-druid-dataset]
Reporter: Stamatis Zampetakis
Queries with aggregation functions on columns of type DOUBLE return results
where the precision of the columns involved in the computation may differ from
one execution to the other.
Consider the following query which can be found under
DruidAdapterIT#testSingleAverageFunction.
{code:sql}
select "store_state", sum("store_cost") / count(*) as a
from "foodmart"
group by "store_state"
order by a desc
{code}
The same query executed multiple times returns different results
+Result 1+
{noformat}
store_state=OR; A=2.6271402406293403
store_state=CA; A=2.599338206292706
store_state=WA; A=2.582870859286872
{noformat}
+Result 2+
{noformat}
store_state=OR; A=2.62714024062934
store_state=CA; A=2.599338206292706
store_state=WA; A=2.582870859286872
{noformat}
+Result 3+
{noformat}
store_state=OR; A=2.6271402406293394
store_state=CA; A=2.599338206292706
store_state=WA; A=2.582870859286872
{noformat}
Column "store_cost" in Druid is defined as shown below:
{noformat}
"metricsSpec" : [
...
{
"name" : "store_sales",
"type" : "doubleSum",
"fieldName" : "store_sales"
}
...]
{noformat}
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