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https://issues.apache.org/jira/browse/PHOENIX-2965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15321443#comment-15321443
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James Taylor commented on PHOENIX-2965:
---------------------------------------
I'd remove the statement.isDistinct() check here as I don't think it's needed
and it might even lead to an issue:
{code}
---
a/phoenix-core/src/main/java/org/apache/phoenix/iterate/BaseResultIterators.java
+++
b/phoenix-core/src/main/java/org/apache/phoenix/iterate/BaseResultIterators.java
@@ -230,7 +230,7 @@ public abstract class BaseResultIterators extends
ExplainTable implements Result
!plan.getStatement().getHint().hasHint(HintNode.Hint.RANGE_SCAN) &&
cols <
plan.getTableRef().getTable().getRowKeySchema().getFieldCount() &&
plan.getGroupBy().isOrderPreserving() &&
- (plan.getStatement().isDistinct() ||
context.getAggregationManager().isEmpty()))
+ (plan.getStatement().isDistinct() ||
context.getAggregationManager().isEmpty() ||
plan.getGroupBy().isUngroupedAggregate()))
{code}
One more test to add would be an aggregate query that does a distinct (in which
case plan.getStatement().isDistinct() would be true). In this case, the
distinct is executed by deduping on the client side. I don't think you'd want
to use the optimization, but it might kick in with out changing the above.
{code}
SELECT DISTINCT sum(pk2) FROM t GROUP BY pk1;
{code}
> Use DistinctPrefixFilter logic for COUNT(DISTINCT ...) and COUNT(...) GROUP BY
> ------------------------------------------------------------------------------
>
> Key: PHOENIX-2965
> URL: https://issues.apache.org/jira/browse/PHOENIX-2965
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Lars Hofhansl
> Fix For: 4.8.0
>
> Attachments: 2965-v2.txt, 2965-v3.txt, 2965-v4.txt, 2965-v5.txt,
> 2965.txt
>
>
> Parent uses skip scanning to optimize DISTINCT and certain GROUP BY
> operations along the row key.
> COUNT queries are optimized differently, could be sped up significantly as
> well.
> [~giacomotaylor], I might need to help into where COUNT(DISTINCT) queries are
> planned and optimized.
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