[jira] [Commented] (CALCITE-1805) Druid adapter incorrectly pushes down "COUNT(c)"; Druid only supports "COUNT(*)"

["slim bouguerra (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16025810#comment-16025810 ] 

slim bouguerra commented on CALCITE-1805:
-----------------------------------------

The example you gave yes but not an arbitrary one like the example below. Your example can be written a count of number of rows returned by group by countryName where countryName not null.
{code} 
select sum(case when "countryName" is null then -1 else 1 end) from "wikiticker"
{code}

> Druid adapter incorrectly pushes down "COUNT(c)"; Druid only supports "COUNT(*)"
> --------------------------------------------------------------------------------
>
>                 Key: CALCITE-1805
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1805
>             Project: Calcite
>          Issue Type: Bug
>          Components: druid
>    Affects Versions: 1.12.0
>            Reporter: slim bouguerra
>            Assignee: Julian Hyde
>
> Currently queries like 
> {code}select count(column) from table{code} is pushed to druid as timeseries with an aggregator {code} {"type":"count","name":"EXPR$0","fieldName":"countryName"} {code}
> Such an aggregator does not exist in druid. The count aggregator does only work as {code} count(*) {code}. 
> here is a test case that summarize the issue.
> {code}  @Test public void testCount() {
>     final String sql = "SELECT count(\"countryName\") FROM (SELECT \"countryName\" FROM \"wikiticker\" WHERE \"countryName\"  IS NOT NULL) as a"; // correct count
>     sql(sql, WIKI_AUTO2).returnsUnordered("EXPR$0=3799");
>     final String sql2 = "SELECT count(\"countryName\") FROM (SELECT \"countryName\" FROM \"wikiticker\") as a";
>     sql(sql2, WIKI_AUTO2).returnsUnordered("EXPR$0=3799"); // it will fail
>   }{code} First test will pass while the second will not.   



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