PREHOOK: query: CREATE TABLE T1(key STRING, val STRING) SKEWED BY (key, val) ON ((2, 12)) STORED AS TEXTFILE PREHOOK: type: CREATETABLE POSTHOOK: query: CREATE TABLE T1(key STRING, val STRING) SKEWED BY (key, val) ON ((2, 12)) STORED AS TEXTFILE POSTHOOK: type: CREATETABLE POSTHOOK: Output: default@T1 PREHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T1.txt' INTO TABLE T1 PREHOOK: type: LOAD PREHOOK: Output: default@t1 POSTHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T1.txt' INTO TABLE T1 POSTHOOK: type: LOAD POSTHOOK: Output: default@t1 PREHOOK: query: CREATE TABLE T2(key STRING, val STRING) SKEWED BY (key) ON ((2)) STORED AS TEXTFILE PREHOOK: type: CREATETABLE POSTHOOK: query: CREATE TABLE T2(key STRING, val STRING) SKEWED BY (key) ON ((2)) STORED AS TEXTFILE POSTHOOK: type: CREATETABLE POSTHOOK: Output: default@T2 PREHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T2.txt' INTO TABLE T2 PREHOOK: type: LOAD PREHOOK: Output: default@t2 POSTHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T2.txt' INTO TABLE T2 POSTHOOK: type: LOAD POSTHOOK: Output: default@t2 PREHOOK: query: -- One of the tables is skewed by 2 columns, and the other table is -- skewed by one column. Ths join is performed on the first skewed column -- The skewed value for the jon key is common to both the tables. -- In this case, the skewed join value is not repeated in the filter. -- adding a order by at the end to make the results deterministic EXPLAIN SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key PREHOOK: type: QUERY POSTHOOK: query: -- One of the tables is skewed by 2 columns, and the other table is -- skewed by one column. Ths join is performed on the first skewed column -- The skewed value for the jon key is common to both the tables. -- In this case, the skewed join value is not repeated in the filter. -- adding a order by at the end to make the results deterministic EXPLAIN SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key POSTHOOK: type: QUERY ABSTRACT SYNTAX TREE: (TOK_QUERY (TOK_FROM (TOK_JOIN (TOK_TABREF (TOK_TABNAME T1) a) (TOK_TABREF (TOK_TABNAME T2) b) (= (. (TOK_TABLE_OR_COL a) key) (. (TOK_TABLE_OR_COL b) key)))) (TOK_INSERT (TOK_DESTINATION (TOK_DIR TOK_TMP_FILE)) (TOK_SELECT (TOK_SELEXPR (TOK_ALLCOLREF (TOK_TABNAME a))) (TOK_SELEXPR (TOK_ALLCOLREF (TOK_TABNAME b)))))) STAGE DEPENDENCIES: Stage-1 is a root stage Stage-2 depends on stages: Stage-1, Stage-4 Stage-4 is a root stage Stage-0 is a root stage STAGE PLANS: Stage: Stage-1 Map Reduce Alias -> Map Operator Tree: subquery1:a TableScan alias: a Filter Operator predicate: expr: (not (key = '2')) type: boolean Reduce Output Operator key expressions: expr: key type: string sort order: + Map-reduce partition columns: expr: key type: string tag: 0 value expressions: expr: key type: string expr: val type: string subquery1:b TableScan alias: b Filter Operator predicate: expr: (not (key = '2')) type: boolean Reduce Output Operator key expressions: expr: key type: string sort order: + Map-reduce partition columns: expr: key type: string tag: 1 value expressions: expr: key type: string expr: val type: string Reduce Operator Tree: Join Operator condition map: Inner Join 0 to 1 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5 Select Operator expressions: expr: _col0 type: string expr: _col1 type: string expr: _col4 type: string expr: _col5 type: string outputColumnNames: _col0, _col1, _col2, _col3 File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.SequenceFileInputFormat output format: org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat Stage: Stage-2 Map Reduce Alias -> Map Operator Tree: #### A masked pattern was here #### TableScan Union Select Operator SELECT * : (no compute) File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.TextInputFormat output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat #### A masked pattern was here #### TableScan Union Select Operator SELECT * : (no compute) File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.TextInputFormat output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat Stage: Stage-4 Map Reduce Alias -> Map Operator Tree: a TableScan alias: a Filter Operator predicate: expr: (key = '2') type: boolean Reduce Output Operator key expressions: expr: key type: string sort order: + Map-reduce partition columns: expr: key type: string tag: 0 value expressions: expr: key type: string expr: val type: string b TableScan alias: b Filter Operator predicate: expr: (key = '2') type: boolean Reduce Output Operator key expressions: expr: key type: string sort order: + Map-reduce partition columns: expr: key type: string tag: 1 value expressions: expr: key type: string expr: val type: string Reduce Operator Tree: Join Operator condition map: Inner Join 0 to 1 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5 Select Operator expressions: expr: _col0 type: string expr: _col1 type: string expr: _col4 type: string expr: _col5 type: string outputColumnNames: _col0, _col1, _col2, _col3 File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.SequenceFileInputFormat output format: org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat Stage: Stage-0 Fetch Operator limit: -1 PREHOOK: query: SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key ORDER BY a.key, b.key, a.val, b.val PREHOOK: type: QUERY PREHOOK: Input: default@t1 PREHOOK: Input: default@t2 #### A masked pattern was here #### POSTHOOK: query: SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key ORDER BY a.key, b.key, a.val, b.val POSTHOOK: type: QUERY POSTHOOK: Input: default@t1 POSTHOOK: Input: default@t2 #### A masked pattern was here #### 2 12 2 22 3 13 3 13 8 18 8 18 8 18 8 18 8 28 8 18 8 28 8 18 PREHOOK: query: DROP TABLE T1 PREHOOK: type: DROPTABLE PREHOOK: Input: default@t1 PREHOOK: Output: default@t1 POSTHOOK: query: DROP TABLE T1 POSTHOOK: type: DROPTABLE POSTHOOK: Input: default@t1 POSTHOOK: Output: default@t1 PREHOOK: query: DROP TABLE T2 PREHOOK: type: DROPTABLE PREHOOK: Input: default@t2 PREHOOK: Output: default@t2 POSTHOOK: query: DROP TABLE T2 POSTHOOK: type: DROPTABLE POSTHOOK: Input: default@t2 POSTHOOK: Output: default@t2 PREHOOK: query: CREATE TABLE T1(key STRING, val STRING) SKEWED BY (key, val) ON ((2, 12)) STORED AS TEXTFILE PREHOOK: type: CREATETABLE POSTHOOK: query: CREATE TABLE T1(key STRING, val STRING) SKEWED BY (key, val) ON ((2, 12)) STORED AS TEXTFILE POSTHOOK: type: CREATETABLE POSTHOOK: Output: default@T1 PREHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T1.txt' INTO TABLE T1 PREHOOK: type: LOAD PREHOOK: Output: default@t1 POSTHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T1.txt' INTO TABLE T1 POSTHOOK: type: LOAD POSTHOOK: Output: default@t1 PREHOOK: query: CREATE TABLE T2(key STRING, val STRING) SKEWED BY (key) ON ((2)) STORED AS TEXTFILE PREHOOK: type: CREATETABLE POSTHOOK: query: CREATE TABLE T2(key STRING, val STRING) SKEWED BY (key) ON ((2)) STORED AS TEXTFILE POSTHOOK: type: CREATETABLE POSTHOOK: Output: default@T2 PREHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T2.txt' INTO TABLE T2 PREHOOK: type: LOAD PREHOOK: Output: default@t2 POSTHOOK: query: LOAD DATA LOCAL INPATH '../data/files/T2.txt' INTO TABLE T2 POSTHOOK: type: LOAD POSTHOOK: Output: default@t2 PREHOOK: query: -- One of the tables is skewed by 2 columns, and the other table is -- skewed by one column. Ths join is performed on the both the columns -- In this case, the skewed join value is repeated in the filter. EXPLAIN SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key and a.val = b.val PREHOOK: type: QUERY POSTHOOK: query: -- One of the tables is skewed by 2 columns, and the other table is -- skewed by one column. Ths join is performed on the both the columns -- In this case, the skewed join value is repeated in the filter. EXPLAIN SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key and a.val = b.val POSTHOOK: type: QUERY ABSTRACT SYNTAX TREE: (TOK_QUERY (TOK_FROM (TOK_JOIN (TOK_TABREF (TOK_TABNAME T1) a) (TOK_TABREF (TOK_TABNAME T2) b) (and (= (. (TOK_TABLE_OR_COL a) key) (. (TOK_TABLE_OR_COL b) key)) (= (. (TOK_TABLE_OR_COL a) val) (. (TOK_TABLE_OR_COL b) val))))) (TOK_INSERT (TOK_DESTINATION (TOK_DIR TOK_TMP_FILE)) (TOK_SELECT (TOK_SELEXPR (TOK_ALLCOLREF (TOK_TABNAME a))) (TOK_SELEXPR (TOK_ALLCOLREF (TOK_TABNAME b)))))) STAGE DEPENDENCIES: Stage-1 is a root stage Stage-2 depends on stages: Stage-1, Stage-4 Stage-4 is a root stage Stage-0 is a root stage STAGE PLANS: Stage: Stage-1 Map Reduce Alias -> Map Operator Tree: subquery1:a TableScan alias: a Filter Operator predicate: expr: (not (((key = '2') and (val = '12')) or (key = '2'))) type: boolean Reduce Output Operator key expressions: expr: key type: string expr: val type: string sort order: ++ Map-reduce partition columns: expr: key type: string expr: val type: string tag: 0 value expressions: expr: key type: string expr: val type: string subquery1:b TableScan alias: b Filter Operator predicate: expr: (not (((key = '2') and (val = '12')) or (key = '2'))) type: boolean Reduce Output Operator key expressions: expr: key type: string expr: val type: string sort order: ++ Map-reduce partition columns: expr: key type: string expr: val type: string tag: 1 value expressions: expr: key type: string expr: val type: string Reduce Operator Tree: Join Operator condition map: Inner Join 0 to 1 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5 Select Operator expressions: expr: _col0 type: string expr: _col1 type: string expr: _col4 type: string expr: _col5 type: string outputColumnNames: _col0, _col1, _col2, _col3 File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.SequenceFileInputFormat output format: org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat Stage: Stage-2 Map Reduce Alias -> Map Operator Tree: #### A masked pattern was here #### TableScan Union Select Operator SELECT * : (no compute) File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.TextInputFormat output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat #### A masked pattern was here #### TableScan Union Select Operator SELECT * : (no compute) File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.TextInputFormat output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat Stage: Stage-4 Map Reduce Alias -> Map Operator Tree: a TableScan alias: a Filter Operator predicate: expr: (((key = '2') and (val = '12')) or (key = '2')) type: boolean Reduce Output Operator key expressions: expr: key type: string expr: val type: string sort order: ++ Map-reduce partition columns: expr: key type: string expr: val type: string tag: 0 value expressions: expr: key type: string expr: val type: string b TableScan alias: b Filter Operator predicate: expr: (((key = '2') and (val = '12')) or (key = '2')) type: boolean Reduce Output Operator key expressions: expr: key type: string expr: val type: string sort order: ++ Map-reduce partition columns: expr: key type: string expr: val type: string tag: 1 value expressions: expr: key type: string expr: val type: string Reduce Operator Tree: Join Operator condition map: Inner Join 0 to 1 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5 Select Operator expressions: expr: _col0 type: string expr: _col1 type: string expr: _col4 type: string expr: _col5 type: string outputColumnNames: _col0, _col1, _col2, _col3 File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.SequenceFileInputFormat output format: org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat Stage: Stage-0 Fetch Operator limit: -1 PREHOOK: query: SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key and a.val = b.val ORDER BY a.key, b.key, a.val, b.val PREHOOK: type: QUERY PREHOOK: Input: default@t1 PREHOOK: Input: default@t2 #### A masked pattern was here #### POSTHOOK: query: SELECT a.*, b.* FROM T1 a JOIN T2 b ON a.key = b.key and a.val = b.val ORDER BY a.key, b.key, a.val, b.val POSTHOOK: type: QUERY POSTHOOK: Input: default@t1 POSTHOOK: Input: default@t2 #### A masked pattern was here #### 3 13 3 13 8 18 8 18 8 18 8 18