Package org.basex.query.util.index

Class IndexInfo

java.lang.Object

org.basex.query.util.index.IndexInfo

public final class IndexInfo
extends Object

This class contains methods for storing information on new index expressions.

Author:

BaseX Team 2005-21, BSD License, Christian Gruen

Field Summary

Fields

Modifier and Type	Field	Description
final CompileContext	cc	Compilation context.
IndexCosts	costs	Costs of index access (null) if no index access is possible).
final IndexDb	db	Index database.
Expr	expr	Index expression.
String	optInfo	Optimization info.
final Step	step	Step with predicate that can be rewritten for index access.
NameTest	test	Name test of parent element.

Constructor Summary

Constructors

Constructor	Description
IndexInfo(IndexDb db, CompileContext cc, Step step)	Constructor.

Method Summary

Modifier and Type	Method	Description
IndexCosts	costs(Data data, IndexSearch search)	Computes costs if the specified data reference exists.
boolean	create(Expr search, IndexType type, boolean trim, InputInfo ii)	Tries to rewrite the specified input for index access.
void	create(ParseExpr root, boolean parent, String opt, InputInfo ii)	Creates an index expression with an inverted axis path.
boolean	enforce()	Indicates if the index rewriting should be enforced.
IndexType	type(Expr input, IndexType type)	Checks if the specified expression can be rewritten for index access, and returns the applicable index type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

cc

public final CompileContext cc

Compilation context.

db

public final IndexDb db

Index database.

step

public final Step step

Step with predicate that can be rewritten for index access.

optInfo

public String optInfo

Optimization info.

test

public NameTest test

Name test of parent element.

expr

public Expr expr

Index expression.

costs

public IndexCosts costs

Costs of index access (null) if no index access is possible).

Constructor Details

IndexInfo

public IndexInfo(IndexDb db,
 CompileContext cc,
 Step step)

Constructor.

Parameters:

db - index database

cc - compilation context

step - step containing the rewritable predicate

Method Details

type

public IndexType type(Expr input,
 IndexType type)

Checks if the specified expression can be rewritten for index access, and returns the applicable index type.

Parameters:

input - input (if null, no optimization will be possible)

type - index type, predefined by the called expression (can be null)

Returns:

supplied type, IndexType.TEXT, IndexType.ATTRIBUTE, or null if index access is not possible

create

public boolean create(Expr search,
 IndexType type,
 boolean trim,
 InputInfo ii)
               throws QueryException

Tries to rewrite the specified input for index access.

Parameters:

search - expression to find (can be null)

type - index type (can be null)

trim - normalize second string

ii - input info (can be null)

Returns:

success flag

Throws:

QueryException - query exception

create

public void create(ParseExpr root,
 boolean parent,
 String opt,
 InputInfo ii)
            throws QueryException

Creates an index expression with an inverted axis path.

Parameters:

root - new root expression

parent - add parent step

opt - optimization info

ii - input info

Throws:

QueryException - query exception

costs

public IndexCosts costs(Data data,
 IndexSearch search)

Computes costs if the specified data reference exists.

Parameters:

data - data reference

search - index search definition

Returns:

costs costs, or null if index access is not possible

enforce

public boolean enforce()

Indicates if the index rewriting should be enforced.

Returns:

result of check