Package 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, ExpressionParser) 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	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 enum	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	Description
boolean	containsSpecializedNodes()	Returns true if this expression or any of its arguments (recursively) has DruidExpression.NodeType.SPECIALIZED type, indicating the expression would benefit from virtual column specialization.
static String	doubleLiteral(double n)
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, List<DruidExpression> args)	Deprecated. use functionCall(String) instead
static String	functionCall(String functionName, 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	isArray()
boolean	isDirectColumnAccess()
boolean	isIdentifierOrSpecialized()	Returns whether this expression is DruidExpression.NodeType.IDENTIFIER or DruidExpression.NodeType.SPECIALIZED.
boolean	isSimpleExtraction()
static String	longLiteral(long n)
DruidExpression	map(Function<SimpleExtraction,SimpleExtraction> extractionMap, Function<String,String> expressionMap)
DruidExpression	map(Function<SimpleExtraction,SimpleExtraction> extractionMap, Function<String,String> expressionMap, ColumnType newType)
static String	nullLiteral()
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	ofLiteral(DruidLiteral literal)	Create a literal expression from an ExprEval.
static DruidExpression	ofStringLiteral(String s)
static DruidExpression	ofVirtualColumn(ColumnType type, DruidExpression.ExpressionGenerator expressionGenerator, List<DruidExpression> arguments, DruidExpression.VirtualColumnCreator virtualColumnCreator)
static String	stringLiteral(String s)
VirtualColumn	toExpressionVirtualColumn(String name, ColumnType outputType, ExpressionParser parser)
String	toString()
VirtualColumn	toVirtualColumn(String name, ColumnType outputType, ExpressionParser parser)
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 Details

longLiteral

public static String longLiteral(long n)

doubleLiteral

public static String doubleLiteral(double 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)

ofLiteral

public static DruidExpression ofLiteral(DruidLiteral literal)

Create a literal expression from an ExprEval.

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()

isArray

public boolean isArray()

getArguments

public List<DruidExpression> getArguments()

Get sub DruidExpression arguments of this expression

toVirtualColumn

public VirtualColumn toVirtualColumn(String name,
 ColumnType outputType,
 ExpressionParser parser)

toExpressionVirtualColumn

public VirtualColumn toExpressionVirtualColumn(String name,
 ColumnType outputType,
 ExpressionParser parser)

getType

public DruidExpression.NodeType getType()

isIdentifierOrSpecialized

public boolean isIdentifierOrSpecialized()

Returns whether this expression is DruidExpression.NodeType.IDENTIFIER or DruidExpression.NodeType.SPECIALIZED. Useful because these are the expressions that can be expected to become direct column references once virtual columns have gone through a specialization pass.

containsSpecializedNodes

public boolean containsSpecializedNodes()

Returns true if this expression or any of its arguments (recursively) has DruidExpression.NodeType.SPECIALIZED type, indicating the expression would benefit from virtual column specialization.

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, ExpressionParser) 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)

map

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

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