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https://issues.apache.org/jira/browse/DRILL-1946?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aman Sinha resolved DRILL-1946.
-------------------------------
Resolution: Duplicate
Closing as duplicate as per previous comment. I will add a separate unit test
for this.
> Wrong result for aggregation query with lower slice_target
> ----------------------------------------------------------
>
> Key: DRILL-1946
> URL: https://issues.apache.org/jira/browse/DRILL-1946
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Affects Versions: 0.7.0
> Reporter: Aman Sinha
> Assignee: Aman Sinha
> Fix For: 0.8.0
>
>
> Here's the result with the default value of slice_target for the following
> query:
> {code}
> select count(*) from (
> SELECT l_suppkey, sum(l_extendedprice)/sum(l_quantity)
> FROM cp.`tpch/lineitem.parquet`
> WHERE (l_orderkey in (SELECT o_orderkey FROM cp.`tpch/orders.parquet`
> WHERE o_custkey < 2) )
> GROUP BY l_suppkey
> );
> +------------+
> | EXPR$0 |
> +------------+
> | 29 |
> +------------+
> {code}
> I lowered the slice_target in order to force exchanges in the following
> query. The result is wrong.
> {code}
> 0: jdbc:drill:zk=local> alter session set `planner.slice_target` = 1;
> select count(*) from (
> SELECT l_suppkey, sum(l_extendedprice)/sum(l_quantity)
> FROM cp.`tpch/lineitem.parquet`
> WHERE (l_orderkey in (SELECT o_orderkey FROM cp.`tpch/orders.parquet`
> WHERE o_custkey < 2) )
> GROUP BY l_suppkey
> );
> +------------+
> | EXPR$0 |
> +------------+
> | 14 |
> +------------+
> {code}
> The Explain plan for the second query has multiphase aggregates. When I set
> planner.enable_multiphase_agg = false, the result is correct, so it seems to
> be a multiphase aggregate issue based on a preliminary analysis (although
> there might be other things going on).
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