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https://issues.apache.org/jira/browse/PHOENIX-3158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15410751#comment-15410751
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Lars Hofhansl commented on PHOENIX-3158:
----------------------------------------
That happens even though the DistinctPrefixFilter is not even used in this
case. It has to do with the plan massaging done in this case.
{noformat}
select /*+ RANGE_SCAN */ count(distinct(pk1)) from test1 where c1 < 0;
+------------------------+
| DISTINCT_COUNT("PK1") |
+------------------------+
| 0 |
+------------------------+
select count(distinct(pk1)) from test1 where c1 < 0;
+------------------------+
| DISTINCT_COUNT("PK1") |
+------------------------+
+------------------------+
explain select /*+ RANGE_SCAN */ count(distinct(pk1)) from test1 where c1 < 0;
+-----------------------------------------------------------------------------------------------+
| PLAN
|
+-----------------------------------------------------------------------------------------------+
| CLIENT 4-CHUNK 566237 ROWS 41943207 BYTES PARALLEL 4-WAY RANGE SCAN OVER
TEST1 [1,*] - [1,0] |
| SERVER FILTER BY FIRST KEY ONLY
|
| SERVER AGGREGATE INTO SINGLE ROW
|
+-----------------------------------------------------------------------------------------------+
explain select count(distinct(pk1)) from test1 where c1 < 0;
+-----------------------------------------------------------------------------------------------+
| PLAN
|
+-----------------------------------------------------------------------------------------------+
| CLIENT 4-CHUNK 566237 ROWS 41943207 BYTES PARALLEL 4-WAY RANGE SCAN OVER
TEST1 [1,*] - [1,0] |
| SERVER FILTER BY FIRST KEY ONLY
|
| SERVER AGGREGATE INTO SINGLE ROW
|
| CLIENT MERGE SORT
|
+-----------------------------------------------------------------------------------------------+
{noformat}
> COUNT(DISTINCT) may return null install of 0 after PHOENIX-258
> --------------------------------------------------------------
>
> Key: PHOENIX-3158
> URL: https://issues.apache.org/jira/browse/PHOENIX-3158
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Lars Hofhansl
> Fix For: 4.8.1
>
> Attachments: 3158.txt
>
>
> This is fine to fix in 4.8.1.
> I'll attach a test to indicate the issue.
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