org.apache.druid.sql.calcite.expression

Class DruidExpression

java.lang.Object

org.apache.druid.sql.calcite.expression.DruidExpression

public class DruidExpression
extends Object

Represents two kinds of expression-like concepts that native Druid queries support: (1) SimpleExtractions, which are direct column access, possibly with an extractionFn (2) native Druid expressions and virtual columns When added to VirtualColumnRegistry whenever used by projections, filters, aggregators, or other query components, these will be converted into native virtual columns using toVirtualColumn(String, ColumnType, ExprMacroTable) Approximate expression structure is retained in the arguments, which when fed into the DruidExpression.ExpressionGenerator that all DruidExpression must be created with will produce the final String expression (which will be later parsed into Expr during native processing). This allows using the DruidExpression.DruidExpressionShuttle to examine this expression "tree" and potentially rewrite some or all of the tree as it visits nodes, and the nodeType property provides high level classification of the types of expression which a node produces.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	DruidExpression.DruidExpressionCreator Create a DruidExpression given some set of input argument sub-expressions
static interface	DruidExpression.DruidExpressionShuttle
static interface	DruidExpression.ExpressionGenerator Used by DruidExpression to compile a string which can be parsed into an Expr from given the sub-expression arguments
static class	DruidExpression.ExpressionVirtualColumnCreator
static class	DruidExpression.IdentifierExpressionGenerator Direct reference to a physical or virtual column
static class	DruidExpression.LiteralExpressionGenerator Builds expressions for a static constant value
static class	DruidExpression.NodeType
static interface	DruidExpression.VirtualColumnCreator Used by a DruidExpression to translate itself into a VirtualColumn to add to a native query when referenced by a projection, filter, aggregator, etc.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
static DruidExpression	fromColumn(String column) Deprecated. use ofColumn(ColumnType, String) or ofColumn(ColumnType, String, SimpleExtraction) instead
static DruidExpression	fromExpression(String expression) Deprecated. use ofExpression(ColumnType, ExpressionGenerator, List) instead to participate in virtual column and expression optimization
static DruidExpression	fromFunctionCall(String functionName, List<DruidExpression> args) Deprecated. use ofFunctionCall(ColumnType, String, List) instead to participate in virtual column and expression optimization
static DruidExpression.ExpressionGenerator	functionCall(String functionName)
static String	functionCall(String functionName, DruidExpression... args) Deprecated. use functionCall(String) instead
static String	functionCall(String functionName, List<DruidExpression> args) Deprecated. use functionCall(String) instead
List<DruidExpression>	getArguments() Get sub DruidExpression arguments of this expression
String	getDirectColumn()
ColumnType	getDruidType() The ColumnType of this expression as inferred when this expression was created.
String	getExpression()
SimpleExtraction	getSimpleExtraction()
DruidExpression.NodeType	getType()
int	hashCode()
boolean	isDirectColumnAccess()
boolean	isSimpleExtraction()
DruidExpression	map(Function<SimpleExtraction,SimpleExtraction> extractionMap, Function<String,String> expressionMap)
static String	nullLiteral()
static String	numberLiteral(Number n)
static DruidExpression	of(SimpleExtraction simpleExtraction, String expression) Deprecated. use ofExpression(ColumnType, SimpleExtraction, ExpressionGenerator, List) instead to participate in virtual column and expression optimization
static DruidExpression	ofColumn(ColumnType columnType, String column)
static DruidExpression	ofColumn(ColumnType columnType, String column, SimpleExtraction simpleExtraction)
static DruidExpression	ofExpression(ColumnType columnType, DruidExpression.ExpressionGenerator expressionGenerator, List<DruidExpression> arguments)
static DruidExpression	ofExpression(ColumnType columnType, SimpleExtraction simpleExtraction, DruidExpression.ExpressionGenerator expressionGenerator, List<DruidExpression> arguments)
static DruidExpression	ofFunctionCall(ColumnType columnType, String functionName, List<DruidExpression> args)
static DruidExpression	ofLiteral(ColumnType columnType, String literal)
static DruidExpression	ofStringLiteral(String s)
static DruidExpression	ofVirtualColumn(ColumnType type, DruidExpression.ExpressionGenerator expressionGenerator, List<DruidExpression> arguments, DruidExpression.VirtualColumnCreator virtualColumnCreator)
Expr	parse(ExprMacroTable macroTable) Compile the DruidExpression into a string and parse it into a native Druid Expr
static String	stringLiteral(String s)
VirtualColumn	toExpressionVirtualColumn(String name, ColumnType outputType, ExprMacroTable macroTable)
String	toString()
VirtualColumn	toVirtualColumn(String name, ColumnType outputType, ExprMacroTable macroTable)
DruidExpression	visit(DruidExpression.DruidExpressionShuttle shuttle) Visit all sub DruidExpression (the arguments of this expression), allowing the DruidExpression.DruidExpressionShuttle to potentially rewrite these arguments with new DruidExpression, finally building a new version of this DruidExpression with updated arguments.
DruidExpression	withArguments(List<DruidExpression> newArgs)

Methods inherited from class java.lang.Object

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

Method Detail

numberLiteral

public static String numberLiteral(Number n)

stringLiteral

public static String stringLiteral(String s)

nullLiteral

public static String nullLiteral()

functionCall

public static DruidExpression.ExpressionGenerator functionCall(String functionName)

functionCall

@Deprecated
public static String functionCall(String functionName,
                                              List<DruidExpression> args)

Deprecated. use functionCall(String) instead

functionCall

@Deprecated
public static String functionCall(String functionName,
                                              DruidExpression... args)

Deprecated. use functionCall(String) instead

ofLiteral

public static DruidExpression ofLiteral(@Nullable
                                        ColumnType columnType,
                                        String literal)

ofStringLiteral

public static DruidExpression ofStringLiteral(String s)

ofColumn

public static DruidExpression ofColumn(@Nullable
                                       ColumnType columnType,
                                       String column,
                                       SimpleExtraction simpleExtraction)

ofColumn

public static DruidExpression ofColumn(ColumnType columnType,
                                       String column)

ofFunctionCall

public static DruidExpression ofFunctionCall(ColumnType columnType,
                                             String functionName,
                                             List<DruidExpression> args)

ofVirtualColumn

public static DruidExpression ofVirtualColumn(ColumnType type,
                                              DruidExpression.ExpressionGenerator expressionGenerator,
                                              List<DruidExpression> arguments,
                                              DruidExpression.VirtualColumnCreator virtualColumnCreator)

ofExpression

public static DruidExpression ofExpression(@Nullable
                                           ColumnType columnType,
                                           DruidExpression.ExpressionGenerator expressionGenerator,
                                           List<DruidExpression> arguments)

ofExpression

public static DruidExpression ofExpression(@Nullable
                                           ColumnType columnType,
                                           SimpleExtraction simpleExtraction,
                                           DruidExpression.ExpressionGenerator expressionGenerator,
                                           List<DruidExpression> arguments)

of

@Deprecated
public static DruidExpression of(SimpleExtraction simpleExtraction,
                                             String expression)

Deprecated. use ofExpression(ColumnType, SimpleExtraction, ExpressionGenerator, List) instead to participate in virtual column and expression optimization

fromColumn

@Deprecated
public static DruidExpression fromColumn(String column)

Deprecated. use ofColumn(ColumnType, String) or ofColumn(ColumnType, String, SimpleExtraction) instead

fromExpression

@Deprecated
public static DruidExpression fromExpression(String expression)

Deprecated. use ofExpression(ColumnType, ExpressionGenerator, List) instead to participate in virtual column and expression optimization

fromFunctionCall

@Deprecated
public static DruidExpression fromFunctionCall(String functionName,
                                                           List<DruidExpression> args)

Deprecated. use ofFunctionCall(ColumnType, String, List) instead to participate in virtual column and expression optimization

getExpression

public String getExpression()

isDirectColumnAccess

public boolean isDirectColumnAccess()

getDirectColumn

public String getDirectColumn()

isSimpleExtraction

public boolean isSimpleExtraction()

getSimpleExtraction

public SimpleExtraction getSimpleExtraction()

getArguments

public List<DruidExpression> getArguments()

Get sub DruidExpression arguments of this expression

parse

public Expr parse(ExprMacroTable macroTable)

Compile the DruidExpression into a string and parse it into a native Druid Expr

toVirtualColumn

public VirtualColumn toVirtualColumn(String name,
                                     ColumnType outputType,
                                     ExprMacroTable macroTable)

toExpressionVirtualColumn

public VirtualColumn toExpressionVirtualColumn(String name,
                                               ColumnType outputType,
                                               ExprMacroTable macroTable)

getType

public DruidExpression.NodeType getType()

getDruidType

@Nullable
public ColumnType getDruidType()

The ColumnType of this expression as inferred when this expression was created. This is likely the result of converting the output of RexNode.getType() using Calcites.getColumnTypeForRelDataType(RelDataType), but may also be supplied by other means. This value is not currently used other than for tracking the types of the DruidExpression tree. The value passed to toVirtualColumn(String, ColumnType, ExprMacroTable) will instead be whatever type "hint" was specified when the expression was added to the VirtualColumnRegistry.

map

public DruidExpression map(Function<SimpleExtraction,SimpleExtraction> extractionMap,
                           Function<String,String> expressionMap)

withArguments

public DruidExpression withArguments(List<DruidExpression> newArgs)

visit

public DruidExpression visit(DruidExpression.DruidExpressionShuttle shuttle)

Visit all sub DruidExpression (the arguments of this expression), allowing the DruidExpression.DruidExpressionShuttle to potentially rewrite these arguments with new DruidExpression, finally building a new version of this DruidExpression with updated arguments.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object