org.eigenbase.sql
Class SqlAggFunction

java.lang.Object
  org.eigenbase.sql.SqlOperator
      org.eigenbase.sql.SqlFunction
          org.eigenbase.sql.SqlAggFunction

All Implemented Interfaces:

Aggregation

Direct Known Subclasses:

SqlAvgAggFunction, SqlCountAggFunction, SqlFirstLastValueAggFunction, SqlHistogramAggFunction, SqlMinMaxAggFunction, SqlRankFunction, SqlSingleValueAggFunction, SqlSumAggFunction, SqlSumEmptyIsZeroAggFunction

public abstract class SqlAggFunction
extends SqlFunction
implements Aggregation

Abstract base class for the definition of an aggregate function: an operator which aggregates sets of values into a result.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/SqlAggFunction.java#20 $

Author:

jhyde

Field Summary

Fields inherited from class org.eigenbase.sql.SqlOperator

MaxPrec, NL

Constructor Summary

SqlAggFunction(String name, SqlKind kind, SqlReturnTypeInference returnTypeInference, SqlOperandTypeInference operandTypeInference, SqlOperandTypeChecker operandTypeChecker, SqlFunctionCategory funcType)

Method Summary

OJClass[]	getStartParameterTypes()
boolean	isQuantifierAllowed() Returns whether this function allows a DISTINCT or ALL quantifier.
void	validateCall(SqlCall call, SqlValidator validator, SqlValidatorScope scope, SqlValidatorScope operandScope) Validates a call to this operator.

Methods inherited from class org.eigenbase.sql.SqlFunction

deriveType, getFunctionType, getNameAsId, getParamTypes, getSqlIdentifier, getSyntax, unparse, validateQuantifier

Methods inherited from class org.eigenbase.sql.SqlOperator

acceptCall, acceptCall, adjustType, argumentMustBeScalar, checkOperandCount, checkOperandTypes, createCall, createCall, createCall, createCall, equals, getAllowedSignatures, getAllowedSignatures, getKind, getLeftPrec, getMonotonicity, getName, getOperandCountRange, getOperandTypeChecker, getOperandTypeInference, getReturnTypeInference, getRightPrec, getSignatureTemplate, hashCode, inferReturnType, inferReturnType, isAggregator, isDeterministic, isDynamicFunction, isName, leftPrec, preValidateCall, requiresDecimalExpansion, rewriteCall, rightPrec, toString, unparseListClause, unparseListClause, validateOperands

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eigenbase.rel.Aggregation

getName, getParameterTypes, getReturnType

Constructor Detail

SqlAggFunction

public SqlAggFunction(String name,
                      SqlKind kind,
                      SqlReturnTypeInference returnTypeInference,
                      SqlOperandTypeInference operandTypeInference,
                      SqlOperandTypeChecker operandTypeChecker,
                      SqlFunctionCategory funcType)

Method Detail

getStartParameterTypes

public OJClass[] getStartParameterTypes()

isQuantifierAllowed

public boolean isQuantifierAllowed()

Description copied from class: SqlFunction

Returns whether this function allows a DISTINCT or ALL quantifier. The default is false; some aggregate functions return true.

Overrides:

isQuantifierAllowed in class SqlFunction

validateCall

public void validateCall(SqlCall call,
                         SqlValidator validator,
                         SqlValidatorScope scope,
                         SqlValidatorScope operandScope)

Description copied from class: SqlOperator

Validates a call to this operator.

This method should not perform type-derivation or perform validation related related to types. That is done later, by SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall). This method should focus on structural validation.

A typical implementation of this method first validates the operands, then performs some operator-specific logic. The default implementation just validates the operands.

This method is the default implementation of SqlCall.validate(org.eigenbase.sql.validate.SqlValidator, org.eigenbase.sql.validate.SqlValidatorScope); but note that some sub-classes of SqlCall never call this method.

Overrides:

validateCall in class SqlFunction

Parameters:

call - the call to this operator

validator - the active validator

scope - validator scope

operandScope - validator scope in which to validate operands to this call; usually equal to scope, but not always because some operators introduce new scopes

See Also:

SqlNode.validateExpr(SqlValidator, SqlValidatorScope), SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall)