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BQL examples (#41)
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‎docs/ws/api.md‎

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@@ -12,78 +12,115 @@ Bullet-BQL provides users with a friendly SQL-like API to submit queries to the
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## Statement Syntax
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SELECT select
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FROM stream
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`query` is one of
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innerQuery
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outerQuery
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where `innerQuery` is
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SELECT select FROM stream
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( LATERAL VIEW lateralView )?
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( WHERE expression )?
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( GROUP BY expression ( , expression )* )?
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( GROUP BY expressions )?
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( HAVING expression )?
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( ORDER BY orderBy )?
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( WINDOWING window )?
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( LIMIT Integer )?
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';'?
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where `select` is
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and `outerQuery` is
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SELECT select FROM ( innerQuery )
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( LATERAL VIEW lateralView )?
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( WHERE expression )?
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( GROUP BY expressions )?
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( HAVING expression )?
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( ORDER BY orderBy )?
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( LIMIT Integer )?
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where `select` is
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DISTINCT? selectItem ( , selectItem )*
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and `selectItem` is one of
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expression ( AS? identifier )?
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tableFunction
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*
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and `expression` is one of
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valueExpression
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fieldExpression
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fieldExpression ( : fieldType )?
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subFieldExpression ( : fieldType )?
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subSubFieldExpression ( : fieldType )?
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listExpression
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expression IS NULL
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expression IS NOT NULL
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unaryExpression
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functionExpression
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expression NOT? IN expression
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expression RLIKE ANY? expression
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expression ( * | / ) expression
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functionExpression
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expression ( * | / | % ) expression
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expression ( + | - ) expression
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expression ( < | <= | > | >= ) ( ANY | ALL )? expression
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expression ( = | != ) ( ANY | ALL )? expression
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expression ( = | != ) ( ANY | ALL )? expression
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expression NOT? RLIKE ANY? expression
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expression NOT? IN expression
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expression NOT? IN ( expressions )
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expressioon NOT? BETWEEN ( expression, expression )
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expression AND expression
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expression XOR expression
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expression OR expression
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( expression )
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where `valueExpression` is one of Null, Boolean, Integer, Long, Float, Double, or String
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and `expressions` is
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expression ( , expression )*
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and `fieldExpression` is one of
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where `valueExpression` is one of Null, Boolean, Integer, Long, Float, Double, String, or `NOW` - a keyword that is converted to the current unix time in milliseconds
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identifier ( : fieldType )?
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identifier [ Integer ] ( : fieldType )?
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identifier [ Integer ] . identifier ( : fieldType )?
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identifier . identifier ( : fieldType )?
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identifier . identifier . identifier ( : fieldType )?
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and `fieldExpression` is
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identifier
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and `subFieldExpression` is one of
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fieldExpression [ Integer ]
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fieldExpression [ String ]
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fieldExpression [ expression ]
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fieldExpression . identifier
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and `subSubFieldExpression` is one of
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subFieldExpression [ String ]
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subFieldExpression [ expression ]
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subFieldExpression . identifier
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`fieldType` is one of
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primitiveType
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LIST [ primitiveType ]
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MAP [ primitiveType ]
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LIST [ MAP [ primitiveType ] ]
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MAP [ MAP [ primitiveType ] ]
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and `primitiveType` is `INTEGER`, `LONG`, `FLOAT`, `DOUBLE`, `BOOLEAN`, or `STRING`
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where `listExpression` is one of
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[]
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[ expression ( , expression )* ]
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`unaryExpression` is
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[ expressions ]
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`unaryExpression` is
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( NOT | SIZEOF ) ( expression ) with optional parentheses
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( ABS | TRIM | LOWER | UPPER ) ( expression ) with non-optional parentheses
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`functionExpression` is one of
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( SIZEIS | CONTAINSKEY | CONTAINSVALUE | FILTER ) ( expression, expression )
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IF ( expression ( , expression )* ) three arguments
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( SIZEIS | CONTAINSKEY | CONTAINSVALUE | FILTER ) ( expression , expression )
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UNIXTIMESTAMP ( expressions? ) zero, one, or two arguments
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SUBSTRING ( expressions? ) two or three arguments
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( IF | BETWEEN ) ( expressions? ) three arguments
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aggregateExpression
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CAST ( expression AS primitiveType )
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MANUAL, Number ( , Number )* defined points
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and `tableFunction` is one of
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OUTER? EXPLODE ( expression ) AS identifier explode a list to one column
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OUTER? EXPLODE ( expression ) AS ( identifier , identifier ) explode a map to a key and a value column
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and `stream` is one of
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STREAM() default time duration will be set from BQLConfig
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STREAM( ( Integer | MAX ), TIME ) time based duration control
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STREAM( ( Integer | MAX ), TIME ) time based duration control
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`RECORD` will be supported in the future.
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and `orderBy` is
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and `lateralView` is
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tableFunction (LATERAL VIEW tableFunction)*
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and `orderBy` is
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expression ( ASC | DESC )? ( , expression ( ASC | DESC )? )*
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and `window` is one of
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and `window` is one of
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EVERY ( Integer, ( TIME | RECORD ), include )
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TUMBLING ( Integer, ( TIME | RECORD ) )
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`include` is one of
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`include` is one of
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ALL
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FIRST, Integer, ( TIME | RECORD )

‎docs/ws/examples.md‎

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@@ -156,6 +156,44 @@ WHERE NOT CONTAINSVALUE(data_map, 'btsg8l9b234ha')
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LIMIT 1;
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```
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### Filtering with NOW Keyword
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```SQL
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SELECT *
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FROM STREAM(30000, TIME)
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WHERE event_timestamp >= NOW
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LIMIT 10;
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```
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### BETWEEN Filter
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This query checks to see if the field ```heart_rate``` is in-between 70 and 100 inclusive and returns all records for which this is true. The ```BETWEEN``` operator can be written in two ways as shown below.
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```SQL
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SELECT *
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FROM STREAM(30000, TIME)
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WHERE heart_rate BETWEEN (70, 100)
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LIMIT 10;
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```
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```SQL
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SELECT *
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FROM STREAM(30000, TIME)
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WHERE BETWEEN(heart_rate, 70, 100)
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LIMIT 10;
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```
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### IN Filter
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This query checks to see if the field ```color``` is in the given list and returns all records for which is true.
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```SQL
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SELECT *
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FROM STREAM(30000, TIME)
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WHERE color IN ('red', 'green', 'blue')
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LIMIT 10;
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```
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### Relational Filter comparing to other fields
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Instead of comparing to static, constant values, you may use the extended values notation and set ```kind``` to ```FIELD``` to compare to other fields within the same record. The following query returns the first record for which the ```id``` field is set to the ```uid``` field.
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Note that this also means the order of the items could be off. If two items had ```Count``` within 24 of each other, it is possible that the higher one *may* actually have had a true count *lower* than
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the second one and possibly be ranked higher. There is no such situation in this result set.
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### Lateral View Explode
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```SQL
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SELECT student, score
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FROM STREAM(30000, TIME)
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LATERAL VIEW EXPLODE(test_scores) AS (student, score)
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WHERE score >= 80
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LIMIT 10;
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```
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This query explodes the map ```test_scores``` to the fields ```student``` and ```score```. This effectively generates a record with a key field and value field for each entry in the exploded map.
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The lateral view means the generated records are appended to the original record, though in this query, only the exploded fields have been selected.
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```javascript
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{
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"records":[
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{
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"student": "Roger",
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"score": 90
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},
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{
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"student": "Albert",
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"score": 92
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},
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{
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"student": "Emily",
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"score": 90
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},
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{
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"student": "Winston",
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"score": 81
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},
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{
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"student": "Jeff",
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"score": 95
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},
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{
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"student": "Kristen",
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"score": 97
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},
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{
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"student": "Percy",
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"score": 85
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},
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{
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"student": "Tyson",
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"score": 80
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},
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{
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"student": "Jackie",
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"score": 89
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},
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{
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"student": "Alice",
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"score": 100
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}
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],
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"meta": "<EDITED OUT>"
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}
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```
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### Multiple Lateral View Explodes
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Multiple lateral view explodes can also be chained in the same query. For instance, using the above example, instead of the map ```test_scores```, there is the list of maps ```tests```.
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This list could be exploded into a field ```test_scores``` which could the be exploded into the fields ```student``` and ```score``` as before.
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```SQL
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SELECT student, score
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FROM STREAM(30000, TIME)
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LATERAL VIEW EXPLODE(tests) AS test_scores
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LATERAL VIEW EXPLODE(test_scores) AS (student, score)
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WHERE score >= 80
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LIMIT 10;
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```
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### Outer Query
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```SQL
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SELECT COUNT(*)
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FROM (
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SELECT browser_name, COUNT(*)
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FROM STREAM(30000, TIME)
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GROUP BY browser_name
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HAVING COUNT(*) > 10
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)
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```
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This query has an inner query wrapped by an outer query. Note that the inner query selects from ```STREAM``` and is thus the main query while the outer query selects from the inner query.
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Note also that the inner/main query can have a window while the outer query cannot.
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The query above counts the number of browser names that appear more than 10 times in 30 seconds.
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```javascript
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{
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"records":[
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{
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"COUNT(*)": 6
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}
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],
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"meta": "<EDITED OUT>"
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}
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```
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### Window - Tumbling Group-By
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```SQL

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