Package org.apache.calcite.rex

@DefaultQualifier(value=org.checkerframework.checker.nullness.qual.NonNull.class,locations=FIELD) @DefaultQualifier(value=org.checkerframework.checker.nullness.qual.NonNull.class,locations=PARAMETER) @DefaultQualifier(value=org.checkerframework.checker.nullness.qual.NonNull.class,locations=RETURN) package org.apache.calcite.rex

Provides a language for representing row-expressions.

Life-cycle

A SqlToRelConverter converts a SQL parse tree consisting of SqlNode objects into a relational expression (RelNode). Several kinds of nodes in this tree have row expressions (RexNode).

After the relational expression has been optimized, a JavaRelImplementor converts it into to a plan. If the plan is a Java parse tree, row-expressions are translated into equivalent Java expressions.

Expressions

Every row-expression has a type. (Compare with SqlNode, which is created before validation, and therefore types may not be available.)

Every node in the parse tree is a RexNode. Sub-types are:

• RexLiteral represents a boolean, numeric, string, or date constant, or the value NULL.
• RexVariable represents a leaf of the tree. It has sub-types:
  • RexCorrelVariable is a correlating variable for nested-loop joins
  • RexInputRef refers to a field of an input relational expression
  • RexCall is a call to an operator or function. By means of special operators, we can use this construct to represent virtually every non-leaf node in the tree.
  • RexRangeRef refers to a collection of contiguous fields from an input relational expression. It usually exists only during translation.

Expressions are generally created using a RexBuilder factory.

Related packages

• org.apache.calcite.sql SQL object model
• org.apache.calcite.plan Core classes, including RelDataType and RelDataTypeFactory.

Related Packages

Package	Description
org.apache.calcite	Main package for Calcite, the dynamic data management platform.

Class	Description
LogicVisitor	Visitor pattern for traversing a tree of RexNode objects.
RexAction	Deprecated.
RexAnalyzer	Analyzes an expression, figures out what are the unbound variables, assigns a variety of values to each unbound variable, and evaluates the expression.
RexBiVisitor<R,P>	Visitor pattern for traversing a tree of RexNode objects and passing a payload to each.
RexBiVisitorImpl<R,P>	Default implementation of RexBiVisitor, which visits each node but does nothing while it's there.
RexBuilder	Factory for row expressions.
RexCall	An expression formed by a call to an operator with zero or more expressions as operands.
RexCallBinding	RexCallBinding implements SqlOperatorBinding by referring to an underlying collection of RexNode operands.
RexChecker	Visitor which checks the validity of a RexNode expression.
RexCorrelVariable	Reference to the current row of a correlating relational expression.
RexDigestIncludeType	Defines if type information should be printed for RexLiteral.
RexDynamicParam	Dynamic parameter reference in a row-expression.
RexExecutable	Result of compiling code generated from a RexNode expression.
RexExecutor	Can reduce expressions, writing a literal for each into a list.
RexExecutorImpl	Evaluates a RexNode expression.
RexFieldAccess	Access to a field of a row-expression.
RexFieldCollation	Expression combined with sort flags (DESCENDING, NULLS LAST).
RexInputRef	Variable which references a field of an input relational expression.
RexInterpreter	Evaluates RexNode expressions.
RexLambda	Represents a lambda expression.
RexLambdaRef	Variable that references a field of a lambda expression.
RexLiteral	Constant value in a row-expression.
RexLocalRef	Local variable.
RexMultisetUtil	Utility class for various methods related to multisets.
RexNode	Row expression.
RexNodeAndFieldIndex	RexNodeAndFieldIndex has the same meaning as RexInputRef, they are both reference a field of an input relational expression.
RexNormalize	Context required to normalize a row-expression.
RexOver	Call to an aggregate function over a window.
RexPattern	Deprecated.
RexPatternFieldRef	Variable that references a field of an input relational expression.
RexPermutationShuttle	Visitor which replaces RexLocalRef objects after the expressions in a RexProgram have been reordered.
RexPermuteInputsShuttle	Shuttle which applies a permutation to its input fields.
RexProgram	A collection of expressions which read inputs, compute output expressions, and optionally use a condition to filter rows.
RexProgramBuilder	Workspace for constructing a RexProgram.
RexRangeRef	Reference to a range of columns.
RexShuttle	Passes over a row-expression, calling a handler method for each node, appropriate to the type of the node.
RexSimplify	Context required to simplify a row-expression.
RexSlot	Abstract base class for RexInputRef, RexLocalRef and RexLambdaRef.
RexSlot.SelfPopulatingList	Thread-safe list that populates itself if you make a reference beyond the end of the list.
RexSqlConvertlet	Converts a RexNode expression into a SqlNode expression.
RexSqlConvertletTable	Collection of RexSqlConvertlets.
RexSqlReflectiveConvertletTable	Implementation of RexSqlConvertletTable.
RexSqlStandardConvertletTable	Standard implementation of RexSqlConvertletTable.
RexSubQuery	Scalar expression that represents an IN, EXISTS or scalar sub-query.
RexTableInputRef	Variable which references a column of a table occurrence in a relational plan.
RexTableInputRef.RelTableRef	Identifies uniquely a table by its qualified name and its entity number (occurrence).
RexToSqlNodeConverter	Converts expressions from RexNode to SqlNode.
RexToSqlNodeConverterImpl	Standard implementation of RexToSqlNodeConverter.
RexTransformer	Takes a tree of RexNode objects and transforms it into another in one sense equivalent tree.
RexUnaryBiVisitor<R>	Default implementation of a RexBiVisitor whose payload and return type are the same.
RexUnknownAs	Policy for whether a simplified expression may instead return another value.
RexUtil	Utility methods concerning row-expressions.
RexUtil.ExpandDisjunctionHelper<K>	Helper class that expands predicates from disjunctions (split by K).
RexUtil.ExprSimplifier	Deprecated.
RexUtil.FieldAccessFinder	Visitor which builds a bitmap of the inputs used by an expression.
RexUtil.FixNullabilityShuttle	Shuttle that fixes up an expression to match changes in nullability of input fields.
RexUtil.RexFinder	Visitor that tells whether a node matching a particular description exists in a tree.
RexUtil.SubQueryCollector	Visitor that collects all the top level SubQueries RexSubQuery in a projection list of a given Project.
RexUtil.SubQueryFinder	Visitor that throws Util.FoundOne if applied to an expression that contains a RexSubQuery.
RexVariable	A row-expression which references a field.
RexVisitor<R>	Visitor pattern for traversing a tree of RexNode objects.
RexVisitorImpl<R>	Default implementation of RexVisitor, which visits each node but does nothing while it's there.
RexWindow	Specification of the window of rows over which a RexOver windowed aggregate is evaluated.
RexWindowBound	Abstracts "XX PRECEDING/FOLLOWING" and "CURRENT ROW" bounds for windowed aggregates.
RexWindowBounds	Helpers for RexWindowBound.
RexWindowExclusion	Representation of different kinds of exclude clause in window functions.