Package org.yamcs.yarch.streamsql

Class SelectExpression

java.lang.Object

org.yamcs.yarch.streamsql.SelectExpression

public class SelectExpression
extends Object

Corresponds to a queries like "select 2*x, x+sum(y+3) from t[...] where x>5 group by x" chain of data/processing (D=Data, P=Processing, agg=aggregate):

 (D1)   inputDef             (x,y)
 
 (P1.1) where filter         (x>5)
 (P1.2) aggInputList
 
 (D2)   aggInputDef          (x,y+3)
 
 (P2)   aggSelectList

 (D3)   aggOutputDef         (x,sum(y+3))
 
 (P3)   selectList
 
 (D4)   outputDef            (2*x,x+sum(y+3))
 

P1.2 is performed by the WindowProcessor If there is no aggregate, then P3 follows directly after P1.1

Constructor Summary

Constructors

Constructor	Description
SelectExpression()

Method Summary

Modifier and Type	Method	Description
void	bind(ExecutionContext c)
Stream	execute(ExecutionContext c)
TupleDefinition	getOutputDefinition()
boolean	isFinite()
void	setAscending(boolean ascending)
void	setFirstSource(TupleSourceExpression tsrc)
void	setFollow(boolean follow)
void	setLimit(BigDecimal offset, BigDecimal limit)
void	setSelectList(List<SelectItem> selectList)
void	setWhereClause(Expression whereClause)
void	setWindow(WindowSpecification windowSpec)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SelectExpression

public SelectExpression()

Method Details

setSelectList

public void setSelectList(List<SelectItem> selectList)

setFirstSource

public void setFirstSource(TupleSourceExpression tsrc)

setWhereClause

public void setWhereClause(Expression whereClause)

setWindow

public void setWindow(WindowSpecification windowSpec)

setAscending

public void setAscending(boolean ascending)

setFollow

public void setFollow(boolean follow)

setLimit

public void setLimit(BigDecimal offset,
 BigDecimal limit)

bind

public void bind(ExecutionContext c)
          throws StreamSqlException

Throws:

StreamSqlException

getOutputDefinition

public TupleDefinition getOutputDefinition()

execute

public Stream execute(ExecutionContext c)
               throws StreamSqlException

Throws:

StreamSqlException

isFinite

public boolean isFinite()