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Vineet Garg commented on HIVE-21338: ------------------------------------ [~jcamachorodriguez] Would you mind taking a look at https://github.com/apache/hive/pull/557/ > Remove order by and limit for aggregates > ---------------------------------------- > > Key: HIVE-21338 > URL: https://issues.apache.org/jira/browse/HIVE-21338 > Project: Hive > Issue Type: Improvement > Components: Query Planning > Reporter: Vineet Garg > Assignee: Vineet Garg > Priority: Major > Labels: pull-request-available > Attachments: HIVE-21338.1.patch, HIVE-21338.2.patch, > HIVE-21338.3.patch > > Time Spent: 10m > Remaining Estimate: 0h > > If a query is guaranteed to produce at most one row LIMIT and ORDER BY could > be removed. This saves unnecessary vertex for LIMIT/ORDER BY. > {code:sql} > explain select count(*) cs from store_sales where ss_ext_sales_price > 100.00 > order by cs limit 100 > {code} > {code} > STAGE PLANS: > Stage: Stage-1 > Tez > DagId: vgarg_20190227131959_2914830f-eab6-425d-b9f0-b8cb56f8a1e9:4 > Edges: > Reducer 2 <- Map 1 (CUSTOM_SIMPLE_EDGE) > Reducer 3 <- Reducer 2 (SIMPLE_EDGE) > DagName: vgarg_20190227131959_2914830f-eab6-425d-b9f0-b8cb56f8a1e9:4 > Vertices: > Map 1 > Map Operator Tree: > TableScan > alias: store_sales > filterExpr: (ss_ext_sales_price > 100) (type: boolean) > Statistics: Num rows: 1 Data size: 112 Basic stats: > COMPLETE Column stats: NONE > Filter Operator > predicate: (ss_ext_sales_price > 100) (type: boolean) > Statistics: Num rows: 1 Data size: 112 Basic stats: > COMPLETE Column stats: NONE > Select Operator > Statistics: Num rows: 1 Data size: 112 Basic stats: > COMPLETE Column stats: NONE > Group By Operator > aggregations: count() > mode: hash > outputColumnNames: _col0 > Statistics: Num rows: 1 Data size: 120 Basic stats: > COMPLETE Column stats: NONE > Reduce Output Operator > sort order: > Statistics: Num rows: 1 Data size: 120 Basic stats: > COMPLETE Column stats: NONE > value expressions: _col0 (type: bigint) > Execution mode: vectorized > Reducer 2 > Execution mode: vectorized > Reduce Operator Tree: > Group By Operator > aggregations: count(VALUE._col0) > mode: mergepartial > outputColumnNames: _col0 > Statistics: Num rows: 1 Data size: 120 Basic stats: COMPLETE > Column stats: NONE > Reduce Output Operator > key expressions: _col0 (type: bigint) > sort order: + > Statistics: Num rows: 1 Data size: 120 Basic stats: > COMPLETE Column stats: NONE > TopN Hash Memory Usage: 0.1 > Reducer 3 > Execution mode: vectorized > Reduce Operator Tree: > Select Operator > expressions: KEY.reducesinkkey0 (type: bigint) > outputColumnNames: _col0 > Statistics: Num rows: 1 Data size: 120 Basic stats: COMPLETE > Column stats: NONE > Limit > Number of rows: 100 > Statistics: Num rows: 1 Data size: 120 Basic stats: > COMPLETE Column stats: NONE > File Output Operator > compressed: false > Statistics: Num rows: 1 Data size: 120 Basic stats: > COMPLETE Column stats: NONE > table: > input format: > org.apache.hadoop.mapred.SequenceFileInputFormat > output format: > org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat > serde: > org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe > Stage: Stage-0 > Fetch Operator > limit: 100 > Processor Tree: > ListSink > {code} -- This message was sent by Atlassian JIRA (v7.6.3#76005)