Package org.apache.iotdb.db.mpp.plan.expression

Class ResultColumn

java.lang.Object

org.apache.iotdb.db.mpp.plan.expression.ResultColumn

public class ResultColumn
extends java.lang.Object

ResultColumn is used to represent a result column of a query.

Assume that we have time series in db as follows:
[ root.sg.d.a, root.sg.d.b, root.sg.e.a, root.sg.e.b ]

Example 1: select a, a + b, udf(udf(b)) from root.sg.d, root.sg.e;
• Step 1: constructed by ASTVisitor in StatementGenerator:
  result columns:
  [a, a + b, udf(udf(b))]
• Step 2: concatenated with prefix paths:
  result columns:
  [root.sg.d.a, root.sg.e.a, root.sg.d.a + root.sg.d.b, root.sg.d.a + root.sg.e.b, root.sg.e.a + root.sg.d.b, root.sg.e.a + root.sg.e.b, udf(udf(root.sg.d.b)), udf(udf(root.sg.e.b))]
• Step 3: remove wildcards:
  result columns:
  [root.sg.d.a, root.sg.e.a, root.sg.d.a + root.sg.d.b, root.sg.d.a + root.sg.e.b, root.sg.e.a + root.sg.d.b, root.sg.e.a + root.sg.e.b, udf(udf(root.sg.d.b)), udf(udf(root.sg.e.b))]

Example 2: select *, a + *, udf(udf(*)) from root.sg.d;
• Step 1: constructed by ASTVisitor in StatementGenerator:
  result columns:
  [*, a + * , udf(udf(*))]
• Step 2: concatenated with prefix paths:
  result columns:
  [root.sg.d.*, root.sg.d.a + root.sg.d.*, udf(udf(root.sg.d.*))]
• Step 3: remove wildcards:
  result columns:
  [root.sg.d.a, root.sg.d.b, root.sg.d.a + root.sg.d.a, root.sg.d.a + root.sg.d.b, udf(udf(root.sg.d.a)), udf(udf(root.sg.d.b))]

Constructor Summary

Constructors

Constructor	Description
ResultColumn(java.nio.ByteBuffer byteBuffer)
ResultColumn(Expression expression)
ResultColumn(Expression expression, java.lang.String alias)

Method Summary

Modifier and Type	Method	Description
java.util.List<org.apache.iotdb.commons.path.PartialPath>	collectPaths()
void	concat(java.util.List<org.apache.iotdb.commons.path.PartialPath> prefixPaths, java.util.List<ResultColumn> resultColumns, boolean needAliasCheck)
static ResultColumn	deserialize(java.nio.ByteBuffer byteBuffer)
boolean	equals(java.lang.Object o)
java.lang.String	getAlias()
org.apache.iotdb.tsfile.file.metadata.enums.TSDataType	getDataType()
Expression	getExpression()
java.lang.String	getExpressionString()
java.lang.String	getResultColumnName()
boolean	hasAlias()
int	hashCode()
void	removeWildcards(WildcardsRemover wildcardsRemover, java.util.List<ResultColumn> resultColumns, boolean needAliasCheck)
static void	serialize(ResultColumn resultColumn, java.nio.ByteBuffer byteBuffer)
void	setDataType(org.apache.iotdb.tsfile.file.metadata.enums.TSDataType dataType)
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ResultColumn

public ResultColumn(Expression expression,
                    java.lang.String alias)

ResultColumn

public ResultColumn(Expression expression)

ResultColumn

public ResultColumn(java.nio.ByteBuffer byteBuffer)

Method Detail

concat

public void concat(java.util.List<org.apache.iotdb.commons.path.PartialPath> prefixPaths,
                   java.util.List<ResultColumn> resultColumns,
                   boolean needAliasCheck)
            throws LogicalOptimizeException

Parameters:

prefixPaths - prefix paths in the from clause

resultColumns - used to collect the result columns

needAliasCheck - used to skip illegal alias judgement here. Including !isGroupByLevel because count(*) may be * unfolded to more than one expression, but it still can be aggregated together later.

Throws:

LogicalOptimizeException

removeWildcards

public void removeWildcards(WildcardsRemover wildcardsRemover,
                            java.util.List<ResultColumn> resultColumns,
                            boolean needAliasCheck)
                     throws LogicalOptimizeException

Parameters:

wildcardsRemover - used to remove wildcards from expression and apply slimit & soffset control

resultColumns - used to collect the result columns

needAliasCheck - used to skip illegal alias judgement here. Including !isGroupByLevel because count(*) may be * unfolded to more than one expression, but it still can be aggregated together later.

Throws:

LogicalOptimizeException

collectPaths

public java.util.List<org.apache.iotdb.commons.path.PartialPath> collectPaths()

getExpression

public Expression getExpression()

hasAlias

public boolean hasAlias()

getAlias

public java.lang.String getAlias()

getResultColumnName

public java.lang.String getResultColumnName()

getExpressionString

public java.lang.String getExpressionString()

setDataType

public void setDataType(org.apache.iotdb.tsfile.file.metadata.enums.TSDataType dataType)

getDataType

public org.apache.iotdb.tsfile.file.metadata.enums.TSDataType getDataType()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

hashCode

public final int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public final boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

serialize

public static void serialize(ResultColumn resultColumn,
                             java.nio.ByteBuffer byteBuffer)

deserialize

public static ResultColumn deserialize(java.nio.ByteBuffer byteBuffer)