The top level query expression object. More...

#include <qExpr.h>

Inheritance diagram for ibis::qExpr:

Classes
struct	TTN
	A data structure including a query expression and the list of table names mentioned in the expression. More...

struct	weight
	A functor to be used by the function reorder. More...

Public Types
enum	COMPARE { OP_UNDEFINED, OP_LT, OP_GT, OP_LE, OP_GE, OP_EQ }
	Comparison operator supported in RANGE.

typedef std::vector< TTN >	termTableList

enum	TYPE { LOGICAL_UNDEFINED, LOGICAL_NOT, LOGICAL_AND, LOGICAL_OR, LOGICAL_XOR, LOGICAL_MINUS, RANGE, DRANGE, STRING, ANYSTRING, KEYWORD, ALLWORDS, COMPRANGE, MATHTERM, DEPRECATEDJOIN, TOPK, EXISTS, ANYANY, LIKE, INTHOD, UINTHOD }
	Definition of node types. More...

Public Member Functions
bool	directEval () const
	Can the expression be directly evaluated?

virtual qExpr *	dup () const
	!< Reorder the expressions tree. More...

void	extractDeprecatedJoins (std::vector< const deprecatedJoin * > &) const
	Extract conjunctive terms of the deprecated joins.

qRange *	findRange (const char *vname)
	Find the first range condition involving the named variable.

void	getConjunctiveTerms (termTableList &) const
	Extract the top-level conjunctive terms. More...

qExpr *&	getLeft ()
	Return a pointer to the left child. More...

const qExpr *	getLeft () const
	Return a const pointer to the left child.

qExpr *&	getRight ()
	Return a pointer to the right child. More...

const qExpr *	getRight () const
	Return a const pointer to the right child.

virtual void	getTableNames (std::set< std::string > &plist) const
	Identify the data partitions involved in the query expression. More...

TYPE	getType () const
	Return the node type.

virtual bool	isConstant () const
	Is this expression a constant? A constant remains the same not matter which row it is applied to. More...

virtual bool	isSimple () const
	Is the expression simple? A simple expression contains only range conditions connected with logical operators. More...

bool	isTerminal () const
	Is this expression a terminal node of an expression tree?

virtual uint32_t	nItems () const
	Count the number of items in the query expression.

qExpr &	operator= (const qExpr &rhs)
	Assignment operator.

virtual void	print (std::ostream &) const
	Print out the node in the string form. More...

virtual void	printFull (std::ostream &out) const
	Print out the full expression. More...

	qExpr ()
	Default constructor. It generates a node of undefined type.

	qExpr (TYPE op)
	Construct a node of specified type. Not for implicit type conversion.

	qExpr (TYPE op, qExpr qe1, qExpr qe2)
	Construct a full specified node. More...

	qExpr (const qExpr &qe)
	Copy Constructor. Deep copy.

double	reorder (const weight &)
	After reordering, the lightest weight is one the left side of a group of commutable operators. More...

int	separateSimple (ibis::qExpr &simple, ibis::qExpr &tail) const
	Separate an expression tree into two connected with an AND operator. More...

void	setLeft (qExpr *expr)
	Change the left child. More...

void	setRight (qExpr *expr)
	Change the right child. More...

void	swap (qExpr &rhs)
	Swap the content. No exception expected.

virtual	~qExpr ()
	Destructor. More...

Static Public Member Functions
static std::string	extractTableName (const char *)
	Extract the data partition name from the column name cn. More...

static void	simplify (ibis::qExpr *&)
	Attempt to simplify the query expressions. More...

static void	splitColumnName (const char *, std::string &, std::string &)
	Split the incoming name into data partition name and column name. More...

Protected Member Functions
void	adjust ()
	Adjust the tree to favor the sequential evaluation order. More...

Protected Attributes
qExpr *	left
	The left child.

qExpr *	right
	The right child.

TYPE	type
	The type of node. More...

Detailed Description

The top level query expression object.

It encodes the logical operations between two child expressions, serving as the interior nodes of an expression tree. Leaf nodes are going to be derived later.

Member Enumeration Documentation

enum ibis::qExpr::TYPE

Definition of node types.

Logical operators are listed in the front and leaf node types are listed at the end.

Constructor & Destructor Documentation

ibis::qExpr::qExpr	(	TYPE	op,
		qExpr *	qe1,
		qExpr *	qe2
	)

inline

Construct a full specified node.

The ownership of qe1 and qe2 is transferred to the newly created object. The destructor of this object will delete qe1 and qe2, the user shall not delete them directly or indirectly through the destruction of another object. This constructor is primarily used by the parsers that compose query expressions, where the final query expression tree is passed to the user. This design allows the user to take control of the final query expression without directly managing any of the lower level nodes in the expression tree.

virtual ibis::qExpr::~qExpr ( )

inlinevirtual

Destructor.

It recursively deletes the nodes of an expression tree. In other word, it owns the descendents it points to.

References left, and right.

Member Function Documentation

void ibis::qExpr::adjust ( )

protected

Adjust the tree to favor the sequential evaluation order.

Make the expression tree lean left.

References adjust(), and left.

Referenced by adjust().

virtual qExpr* ibis::qExpr::dup ( ) const

inlinevirtual

!< Reorder the expressions tree.

Duplicate this query expression. Return the pointer to the new object.

Reimplemented in ibis::qAnyAny, ibis::deprecatedJoin, ibis::compRange, ibis::math::stringFunction1, ibis::math::customFunction1, ibis::math::stdFunction2, ibis::math::stdFunction1, ibis::math::bediener, ibis::math::literal, ibis::math::number, ibis::math::variable, ibis::math::term, ibis::qAllWords, ibis::qKeyword, ibis::qLike, ibis::qAnyString, ibis::qExists, ibis::qString, ibis::qUIntHod, ibis::qIntHod, ibis::qDiscreteRange, ibis::qContinuousRange, and ibis::selectClause::variable.

Referenced by ibis::whereClause::addExpr(), ibis::whereClause::setExpr(), and ibis::whereClause::whereClause().

std::string ibis::qExpr::extractTableName ( const char * cn )

static

Extract the data partition name from the column name cn.

It looks for the first period '.' in the column name. If a period is found, the characters before the period is returned as a string, otherwise, an empty string is returned.

Note: The data partition name will be outputed in lowercase characters.

Referenced by ibis::quaere::create(), ibis::qRange::getTableNames(), ibis::qString::getTableNames(), ibis::qAnyString::getTableNames(), ibis::qLike::getTableNames(), ibis::qKeyword::getTableNames(), ibis::qAllWords::getTableNames(), ibis::math::variable::getTableNames(), and ibis::qAnyAny::getTableNames().

void ibis::qExpr::getConjunctiveTerms ( termTableList & ttl ) const

Extract the top-level conjunctive terms.

If the top-most operator is not the AND operator, the whole expression tree is considered one term. Because this function may be called recursively, the argument ttl is not cleared by this function. The caller needs to make sure it is cleared on input.

Referenced by ibis::quaere::create().

qExpr*& ibis::qExpr::getLeft ( )

inline

Return a pointer to the left child.

The pointer can be modified. The object assigned to be the new left child is owned by this object.

References left.

Referenced by ibis::whereClause::amplify(), ibis::quaere::create(), ibis::query::doContract(), ibis::countQuery::doEstimate(), ibis::countQuery::doEvaluate(), ibis::query::doExpand(), ibis::countQuery::doScan(), ibis::part::doScan(), ibis::query::doScan(), ibis::math::bediener::dup(), ibis::math::stdFunction1::dup(), ibis::math::stdFunction2::dup(), ibis::selectClause::hasAggregation(), ibis::compRange::isConstant(), ibis::query::weight::operator()(), ibis::math::barrel::recordVariable(), ibis::math::bediener::reduce(), ibis::math::stdFunction1::reduce(), simplify(), ibis::whereClause::verifyExpr(), and ibis::selectClause::verifyTerm().

qExpr*& ibis::qExpr::getRight ( )

inline

Return a pointer to the right child.

The pointer can be modified. The object assigned to be the new right child of this expression is owned by this object after the assignment.

References right.

Referenced by ibis::whereClause::amplify(), ibis::quaere::create(), ibis::query::doContract(), ibis::countQuery::doEstimate(), ibis::countQuery::doEvaluate(), ibis::query::doExpand(), ibis::countQuery::doScan(), ibis::part::doScan(), ibis::query::doScan(), ibis::math::bediener::dup(), ibis::math::stdFunction2::dup(), ibis::selectClause::hasAggregation(), ibis::compRange::isConstant(), ibis::query::weight::operator()(), ibis::math::barrel::recordVariable(), ibis::math::bediener::reduce(), simplify(), ibis::whereClause::verifyExpr(), and ibis::selectClause::verifyTerm().

void ibis::qExpr::getTableNames ( std::set< std::string > & plist ) const

virtual

Identify the data partitions involved in the query expression.

Return the list of data partition names in a set.

It records a '*' for the variables without explicit partition names.

Reimplemented in ibis::qAnyAny, ibis::compRange, ibis::math::variable, ibis::qAllWords, ibis::qKeyword, ibis::qLike, ibis::qAnyString, ibis::qString, and ibis::qRange.

Referenced by ibis::quaere::create().

virtual bool ibis::qExpr::isConstant ( ) const

inlinevirtual

Is this expression a constant? A constant remains the same not matter which row it is applied to.

Reimplemented in ibis::compRange, ibis::math::literal, and ibis::math::number.

Referenced by ibis::countQuery::doEstimate(), ibis::countQuery::doEvaluate(), ibis::query::doEvaluate(), ibis::countQuery::doScan(), ibis::query::doScan(), and simplify().

virtual bool ibis::qExpr::isSimple ( ) const

inlinevirtual

Is the expression simple? A simple expression contains only range conditions connected with logical operators.

Reimplemented in ibis::compRange, and ibis::qExists.

void ibis::qExpr::print ( std::ostream & out ) const

virtual

Print out the node in the string form.

The short-form of the print function.

It only prints information about the current node of the query expression tree.

Reimplemented in ibis::qAnyAny, ibis::deprecatedJoin, ibis::compRange, ibis::math::stringFunction1, ibis::math::customFunction1, ibis::math::stdFunction2, ibis::math::stdFunction1, ibis::math::bediener, ibis::math::literal, ibis::math::number, ibis::math::variable, ibis::math::term, ibis::qAllWords, ibis::qKeyword, ibis::qLike, ibis::qAnyString, ibis::qExists, ibis::qString, ibis::qUIntHod, ibis::qIntHod, ibis::qDiscreteRange, ibis::qContinuousRange, and ibis::selectClause::variable.

Referenced by ibis::qDiscreteRange::printFull(), ibis::qString::printFull(), ibis::qAnyString::printFull(), ibis::qLike::printFull(), ibis::qKeyword::printFull(), ibis::qAllWords::printFull(), ibis::query::removeComplexConditions(), separateSimple(), and simplify().

void ibis::qExpr::printFull ( std::ostream & out ) const

virtual

Print out the full expression.

The long form of the print function.

It recursively prints out the whole query expression tree, which can be quite long.

Reimplemented in ibis::qAnyAny, ibis::deprecatedJoin, ibis::compRange, ibis::math::stringFunction1, ibis::math::customFunction1, ibis::math::stdFunction2, ibis::math::stdFunction1, ibis::math::bediener, ibis::math::literal, ibis::math::number, ibis::math::variable, ibis::math::term, ibis::qAllWords, ibis::qKeyword, ibis::qLike, ibis::qAnyString, ibis::qExists, ibis::qString, ibis::qUIntHod, ibis::qIntHod, ibis::qDiscreteRange, and ibis::qContinuousRange.

Referenced by ibis::query::setWhereClause(), and simplify().

double ibis::qExpr::reorder ( const weight & wt )

After reordering, the lightest weight is one the left side of a group of commutable operators.

References directEval(), left, reorder(), right, and type.

Referenced by reorder().

int ibis::qExpr::separateSimple	(	ibis::qExpr *&	simple,
		ibis::qExpr *&	tail
	)		const

Separate an expression tree into two connected with an AND operator.

The terms that are simply range conditions are placed in simple, and the remaining conditions are left in tail.

It returns 0 if there is a mixture of simple and complex conditions. In this case, both simple and tail would be non-nil. The return value is -1 if all conditions are complex and 1 if all conditions are simple. In these two cases, both simple and tail are nil.

References left, print(), right, and type.

Referenced by ibis::query::removeComplexConditions().

void ibis::qExpr::setLeft ( qExpr * expr )

inline

Change the left child.

This object takes the ownership of expr. The user can not delete expr either directly or indirectly through the destruction of another object (other than this one, of course).

References left.

Referenced by ibis::quaere::create(), ibis::math::bediener::dup(), ibis::math::stdFunction1::dup(), ibis::math::stdFunction2::dup(), fastbit_selection_combine(), fastbit_selection_create(), fastbit_selection_create_nd(), fastbit_selection_osr(), ibis::query::setWhereClause(), and simplify().

void ibis::qExpr::setRight ( qExpr * expr )

inline

Change the right child.

This object takes the ownership of expr. The user can not delete expr either directly or indirectly through the destruction of another object (other than this one, of course).

References right.

Referenced by ibis::quaere::create(), ibis::math::bediener::dup(), ibis::math::stdFunction2::dup(), fastbit_selection_combine(), ibis::query::setWhereClause(), and simplify().

void ibis::qExpr::simplify ( ibis::qExpr *& expr )

static

Attempt to simplify the query expressions.

Operations performed include converting compRanges into qRanges, qDiscreteRange into qContinuousRange, perform constant evaluations, combining pairs of inverse functions.

This is necessary because the parser always generates compRange instead of qRange. The goal of simplifying arithmetic expressions is to reduce the number of accesses to the variable values (potentially reducing the number of disk accesses).

Note: Be aware that rearranging the arithmetic expressions may affect the round-off perperties of these expressions, and therefore affect their computed results. Even though the typical differences might be small (after ten significant digits), however, the differences could accumulated and became noticeable. To turn off this optimization, set ibis::math::preserveInputExpressions to true.

References ibis::qDiscreteRange::convert(), ibis::qAnyString::convert(), ibis::math::term::eval(), getLeft(), getRight(), getType(), ibis::qContinuousRange::inRange(), isConstant(), left, ibis::compRange::makeConstantFalse(), ibis::qDiscreteRange::nItems(), ibis::math::preserveInputExpressions, print(), printFull(), ibis::math::term::reduce(), right, setLeft(), setRight(), type, and ibis::qAnyString::valueList().

Referenced by ibis::whereClause::amplify(), ibis::whereClause::parse(), and ibis::whereClause::simplify().

void ibis::qExpr::splitColumnName	(	const char *	inm,
		std::string &	pn,
		std::string &	cn
	)

static

Split the incoming name into data partition name and column name.

It looks for the first period '.' in the incoming name. If a period is found, the characters before the period is returned as pn, and the characters after the period is returned as cn. If no period is found, pn will be a blank string and cn will be a copy of inm.

Note: Both output names will be in lower case only.

Member Data Documentation

TYPE ibis::qExpr::type

protected

The type of node.

It indicates the type of the operator or the leaf node.

Referenced by getType(), reorder(), separateSimple(), simplify(), and swap().

The documentation for this class was generated from the following files:

qExpr.h
qExpr.cpp



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Classes

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Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation