com.hp.hpl.jena.query
Class ARQ

java.lang.Object
  com.hp.hpl.jena.query.ARQ

public class ARQ
extends Object

ARQ - miscellaneous settings

Field Summary

static boolean	allowDuplicateSelectColumns Indicate whether duplicate select and groupby variables are allowed.
static String	arqIRI IRI for ARQ
static String	arqParamNS Root of ARQ-defined parameter names
static String	arqSymbolPrefix Prefix for ARQ-defined parameter names
static String	BUILD_DATE The date and time at which this release was built
static Symbol	constantBNodeLabels Controls bNode labels as <_:...> or not - that is a pseudo URIs.
static Symbol	enableExecutionTimeLogging Enable logging of execution timing.
static Symbol	enablePropertyFunctions Enable built-in property functions - also called "magic properties".
static Symbol	extensionValueTypes Expression evaluation without extension types (e.g.
static Symbol	generateToList Generate the ToList operation in the algebra (as ARQ is stream based, ToList is a non-op).
static Symbol	hideNonDistiguishedVariables Context key to control hiding non-distinuished variables
static Symbol	inputGraphBNodeLabels If true, XML result sets will use the bNode label in the result set itself.
static Symbol	javaRegex Symbol to name java.util.regex regular expression engine
static String	logExecName Name of the execution logger
static String	logHttpRequestName Name of the logger for remote HTTP requests
static String	logInfoName Name of the information logger
static String	NAME The product name
static Symbol	optDistinctToReduced Context key controlling whether a DISTINCT-ORDER BY query is done by replacing the distinct with a reduced.
static Symbol	optExprConstantFolding Context key controlling whether the standard optimizer applies constant folding to expressions
static Symbol	optFilterConjunction Context key controlling whether the standard optimizer applies optimizations to conjunctions (&&) in filters.
static Symbol	optFilterDisjunction Context key controlling whether the standard optimizer applies optimizations to disjunctions (||) in filters.
static Symbol	optFilterEquality Context key controlling whether the standard optimizer applies optimizations to equalities in FILTERs.
static Symbol	optFilterExpandOneOf Context key controlling whether the standard optimizer applies optimizations to IN and NOT IN.
static Symbol	optFilterImplicitJoin Context key controlling whether the standard optimizer applies optimizations to implicit joins in FILTERs.
static Symbol	optFilterInequality Context key controlling whether the standard optimizer applies optimizations to inequalities in FILTERs This optimization is conservative - it does not take place if there is a potential risk of changing query semantics
static Symbol	optFilterPlacement Context key controlling whether the main query engine moves filters to the "best" place.
static Symbol	optFilterPlacementBGP Context key controlling whether to do filter placement within BGP and quad blocks.
static Symbol	optFilterPlacementConservative Context key controlling whether the main query engine moves filters to the "best" place using the more limited and conservative strategy which does not place as many filters Must be explicitly set "true" to operate.
static Symbol	optimization Context key controlling whether the main query engine applies the default optimization transformations.
static Symbol	optImplicitLeftJoin Context key controlling whether the standard optimizer applies optimizations to implicit left joins.
static Symbol	optIndexJoinStrategy Context key controlling whether the standard optimizer applies optimizations to the evaluation of joins to favour index joins wherever possible
static Symbol	optMergeBGPs Context key controlling whether the standard optimizater applies optimizations to joined BGPs to merge them into single BGPs
static Symbol	optOrderByDistinctApplication Context key controlling whether a DISTINCT-ORDER BY query is done by applying the ORDER BY after the DISTINCT when default SPARQL semantics usually mean ORDER BY applies before DISTINCT.
static Symbol	optPathFlatten Context key controlling whether the main query engine flattens simple paths (e.g.
static Symbol	optPromoteTableEmpty Context key controlling whether the standard optimizer applies table empty promotion
static Symbol	optTermStrings Context key for a declaration that xsd:strings and simple literals are different in the storage.
static Symbol	optTopNSorting Context key controlling whether an ORDER BY-LIMIT query is done avoiding total sort using an heap.
static Symbol	outputGraphBNodeLabels If true, XML result sets written will contain the graph bNode label See also inputGraphBNodeLabels
static String	PATH The root package name for ARQ
static Symbol	propertyFunctions Context key controlling whether the main query engine
static Symbol	queryTimeout Set timeout.
static Symbol	regexImpl Determine which regular expression system to use.
static Symbol	serviceParams Use this Symbol to allow passing additional query parameters to a SERVICE call.
static Symbol	spillToDiskThreshold A Long value that specifies the number of bindings (or triples for CONSTRUCT queries) to be stored in memory by sort operations or hash tables before switching to temporary disk files.
static Symbol	stageGenerator Context key for StageBuilder used in BGP compilation
static Symbol	strictSPARQL Stick exactly to the spec.
static Symbol	symLogExec Symbol to enable logging of execution.
static Symbol	useSAX Use the SAX parser for XML result sets.
static String	VERSION The full name of the current ARQ version
static Symbol	xercesRegex Symbol to name the Xerces-J regular expression engine

Constructor Summary

ARQ()

Method Summary

static void	enableBlankNodeResultLabels() Turn on processing of blank node labels in queries
static void	enableBlankNodeResultLabels(boolean val) Turn on/off processing of blank node labels in queries
static void	enableOptimizer(boolean state) Globally switch the default optimizer on and off : Note that storage subsystems may also be applying separately controlled optimizations.
static void	enableOptimizer(Context context, boolean state) Switch the default optimizer on and off for a specific Context.
static Context	getContext()
static org.slf4j.Logger	getExecLogger() The execution logger
static Explain.InfoLevel	getExecutionLogging() Get the currently global execution logging setting
static org.slf4j.Logger	getHttpRequestLogger() The HTTP Request logger
static org.slf4j.Logger	getInfoLogger() The information logger
static void	init() Ensure things have started - applications do not need call this.
static boolean	isFalse(Symbol symbol)
static boolean	isFalseOrUndef(Symbol symbol)
static boolean	isStrictMode()
static boolean	isTrue(Symbol symbol)
static boolean	isTrueOrUndef(Symbol symbol)
static void	set(Symbol symbol, boolean value)
static void	setExecutionLogging(Explain.InfoLevel infoLevel) Set execution logging - logging is to logger "com.hp.hpl.jena.arq.exec" at level INFO.
static void	setFalse(Symbol symbol)
static void	setNormalMode() Set normal mode, including expression evaluation
static void	setNormalMode(Context context) Explicitly set the values for normal operation.
static void	setStrictMode() Set strict mode, including expression evaluation
static void	setStrictMode(Context context) Set strict mode for a given Context.
static void	setTrue(Symbol symbol)
static void	unset(Symbol symbol)

Methods inherited from class java.lang.Object

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

Field Detail

logExecName

public static final String logExecName

Name of the execution logger

See Also:

Constant Field Values

logInfoName

public static final String logInfoName

Name of the information logger

See Also:

Constant Field Values

logHttpRequestName

public static final String logHttpRequestName

Name of the logger for remote HTTP requests

See Also:

Constant Field Values

symLogExec

public static final Symbol symLogExec

Symbol to enable logging of execution. Must also set log4j, or other logging system, for logger "com.hp.hpl.jena.sparql.exec" e.g. log4j.properties -- log4j.logger.com.hp.hpl.jena.sparql.exec=INFO See the ARQ Logging Documentation.

arqIRI

public static final String arqIRI

IRI for ARQ

See Also:

Constant Field Values

arqParamNS

public static final String arqParamNS

Root of ARQ-defined parameter names

See Also:

Constant Field Values

arqSymbolPrefix

public static final String arqSymbolPrefix

Prefix for ARQ-defined parameter names

See Also:

Constant Field Values

strictSPARQL

public static final Symbol strictSPARQL

Stick exactly to the spec.

constantBNodeLabels

public static final Symbol constantBNodeLabels

Controls bNode labels as <_:...> or not - that is a pseudo URIs. This does not affect [] or _:a bNodes as variables in queries.

enablePropertyFunctions

public static final Symbol enablePropertyFunctions

Enable built-in property functions - also called "magic properties". These are properties in triple patterns that need calculation, not matching. See ARQ documentation for more details. rdfs:member and http://jena.hpl.hp.com/ARQ/list#member are provided.

enableExecutionTimeLogging

public static final Symbol enableExecutionTimeLogging

Enable logging of execution timing.

outputGraphBNodeLabels

public static final Symbol outputGraphBNodeLabels

If true, XML result sets written will contain the graph bNode label See also inputGraphBNodeLabels

inputGraphBNodeLabels

public static final Symbol inputGraphBNodeLabels

If true, XML result sets will use the bNode label in the result set itself. See also outputGraphBNodeLabels

queryTimeout

public static final Symbol queryTimeout

Set timeout. The value of this symbol gives thevalue of the timeout in milliseconds

• A Number; the long value is used
• A string, e.g. "1000", parsed as a number
• A string, as two numbers separated by a comma, e.g. "500,10000" parsed as two numbers

See Also:

QueryExecution.setTimeout(long), QueryExecution.setTimeout(long,long)

stageGenerator

public static final Symbol stageGenerator

Context key for StageBuilder used in BGP compilation

hideNonDistiguishedVariables

public static final Symbol hideNonDistiguishedVariables

Context key to control hiding non-distinuished variables

useSAX

public static final Symbol useSAX

Use the SAX parser for XML result sets. The default is to use StAX for full streaming of XML results. The SAX parser takes a copy of the result set before giving the ResultSet to the calling application.

allowDuplicateSelectColumns

public static final boolean allowDuplicateSelectColumns

Indicate whether duplicate select and groupby variables are allowed. If false, duplicates are silently supressed; it's not an error.

See Also:

Constant Field Values

regexImpl

public static final Symbol regexImpl

Determine which regular expression system to use. The value of this context entry should be a string or symbol of one of the following: javaRegex : use java.util.regex (support features outside the strict SPARQL regex language) xercesRegex : use the internal XPath regex engine (more compliant)

javaRegex

public static final Symbol javaRegex

Symbol to name java.util.regex regular expression engine

xercesRegex

public static final Symbol xercesRegex

Symbol to name the Xerces-J regular expression engine

serviceParams

public static final Symbol serviceParams

Use this Symbol to allow passing additional query parameters to a SERVICE call. Parameters need to be grouped by SERVICE , a Map>> is assumed. The key of the first map is the SERVICE IRI, the value is a Map which maps the name of a query string parameters to its values.

See Also:

Service

spillToDiskThreshold

public static final Symbol spillToDiskThreshold

A Long value that specifies the number of bindings (or triples for CONSTRUCT queries) to be stored in memory by sort operations or hash tables before switching to temporary disk files. The value defaults to -1, which will always keep the bindings in memory and never write to temporary files. The amount of memory used will vary based on the size of the bindings. If you are retrieving large literal strings, then you may need to lower the value.

Note that for a complex query, several sort or hash operations might be running in parallel; each one will be allowed to retain as many bindings in memory as this value specifies before it starts putting data in temporary files. Also, several running sessions could be doing such operations concurrently. Therefore, the total number of bindings held in memory could be many times this value; it is necessary to keep this fact in mind when choosing the value.

Operations currently affected by this symbol:
ORDER BY, SPARQL Update, CONSTRUCT (optionally)

TODO: Give a reasonable suggested value here. 10,000?

See Also:

JENA-119

optimization

public static final Symbol optimization

Context key controlling whether the main query engine applies the default optimization transformations.

optPathFlatten

public static final Symbol optPathFlatten

Context key controlling whether the main query engine flattens simple paths (e.g. ?x :p/:q ?z => ?x :p ?.0 . ?.0 ?q ?z)

Default is "true"

optFilterPlacement

public static final Symbol optFilterPlacement

Context key controlling whether the main query engine moves filters to the "best" place. Default is "true" - filter placement is done.

optFilterPlacementBGP

public static final Symbol optFilterPlacementBGP

Context key controlling whether to do filter placement within BGP and quad blocks. Modies the effect of optFilterPlacement. Default is "true" - filter placement is pushed into BGPs.

optFilterPlacementConservative

public static final Symbol optFilterPlacementConservative

Context key controlling whether the main query engine moves filters to the "best" place using the more limited and conservative strategy which does not place as many filters Must be explicitly set "true" to operate. Filter placement, via optFilterPlacement must also be active (which it is by default).

See Also:

optFilterPlacement

optTopNSorting

public static final Symbol optTopNSorting

Context key controlling whether an ORDER BY-LIMIT query is done avoiding total sort using an heap. Default is "true" - total sort if avoided by default when ORDER BY is used with LIMIT.

optDistinctToReduced

public static final Symbol optDistinctToReduced

Context key controlling whether a DISTINCT-ORDER BY query is done by replacing the distinct with a reduced. Default is "true" - the reduced operator does not need to keep a data structure with all previously seen bindings.

optOrderByDistinctApplication

public static final Symbol optOrderByDistinctApplication

Context key controlling whether a DISTINCT-ORDER BY query is done by applying the ORDER BY after the DISTINCT when default SPARQL semantics usually mean ORDER BY applies before DISTINCT. This optimization applies only in a subset of cases unlike the more general optDistinctToReduced optimization.

See TransformOrderByDistinctApplication for more discussion on exactly when this may apply

optFilterEquality

public static final Symbol optFilterEquality

Context key controlling whether the standard optimizer applies optimizations to equalities in FILTERs. This optimization is conservative - it does not take place if there is a potential risk of changing query semantics.

optFilterInequality

public static final Symbol optFilterInequality

Context key controlling whether the standard optimizer applies optimizations to inequalities in FILTERs This optimization is conservative - it does not take place if there is a potential risk of changing query semantics

optFilterImplicitJoin

public static final Symbol optFilterImplicitJoin

Context key controlling whether the standard optimizer applies optimizations to implicit joins in FILTERs. This optimization is conservative - it does not take place if there is a potential risk of changing query semantics.

optImplicitLeftJoin

public static final Symbol optImplicitLeftJoin

Context key controlling whether the standard optimizer applies optimizations to implicit left joins. This optimization is conservative - it does not take place if there is a potential risk of changing query semantics.

optTermStrings

public static final Symbol optTermStrings

Context key for a declaration that xsd:strings and simple literals are different in the storage. They are the same value in a memory store. When in doubt, xsd:strings are assumed to be the same value as simple literals

optExprConstantFolding

public static final Symbol optExprConstantFolding

Context key controlling whether the standard optimizer applies constant folding to expressions

optFilterConjunction

public static final Symbol optFilterConjunction

Context key controlling whether the standard optimizer applies optimizations to conjunctions (&&) in filters.

optFilterExpandOneOf

public static final Symbol optFilterExpandOneOf

Context key controlling whether the standard optimizer applies optimizations to IN and NOT IN.

optFilterDisjunction

public static final Symbol optFilterDisjunction

Context key controlling whether the standard optimizer applies optimizations to disjunctions (||) in filters.

optPromoteTableEmpty

public static final Symbol optPromoteTableEmpty

Context key controlling whether the standard optimizer applies table empty promotion

optIndexJoinStrategy

public static final Symbol optIndexJoinStrategy

Context key controlling whether the standard optimizer applies optimizations to the evaluation of joins to favour index joins wherever possible

optMergeBGPs

public static final Symbol optMergeBGPs

Context key controlling whether the standard optimizater applies optimizations to joined BGPs to merge them into single BGPs

propertyFunctions

public static final Symbol propertyFunctions

Context key controlling whether the main query engine

extensionValueTypes

public static final Symbol extensionValueTypes

Expression evaluation without extension types (e.g. xsd:date, language tags)

generateToList

public static final Symbol generateToList

Generate the ToList operation in the algebra (as ARQ is stream based, ToList is a non-op). Default is not to do so. Strict mode will also enable this.

PATH

public static final String PATH

The root package name for ARQ

See Also:

Constant Field Values

NAME

public static final String NAME

The product name

See Also:

Constant Field Values

VERSION

public static final String VERSION

The full name of the current ARQ version

BUILD_DATE

public static final String BUILD_DATE

The date and time at which this release was built

Constructor Detail

ARQ

public ARQ()

Method Detail

getExecLogger

public static org.slf4j.Logger getExecLogger()

The execution logger

getInfoLogger

public static org.slf4j.Logger getInfoLogger()

The information logger

getHttpRequestLogger

public static org.slf4j.Logger getHttpRequestLogger()

The HTTP Request logger

getExecutionLogging

public static Explain.InfoLevel getExecutionLogging()

Get the currently global execution logging setting

setExecutionLogging

public static void setExecutionLogging(Explain.InfoLevel infoLevel)

Set execution logging - logging is to logger "com.hp.hpl.jena.arq.exec" at level INFO. An appropriate logging configuration is also required.

enableBlankNodeResultLabels

public static void enableBlankNodeResultLabels()

Turn on processing of blank node labels in queries

enableBlankNodeResultLabels

public static void enableBlankNodeResultLabels(boolean val)

Turn on/off processing of blank node labels in queries

enableOptimizer

public static void enableOptimizer(boolean state)

Globally switch the default optimizer on and off : Note that storage subsystems may also be applying separately controlled optimizations.

enableOptimizer

public static void enableOptimizer(Context context,
                                   boolean state)

Switch the default optimizer on and off for a specific Context. Note that storage subsystems may also be applying separately controlled optimizations.

setStrictMode

public static void setStrictMode()

Set strict mode, including expression evaluation

setStrictMode

public static void setStrictMode(Context context)

Set strict mode for a given Context. Does not influence expression evaluation because NodeValues are controlled globally, not per context.

isStrictMode

public static boolean isStrictMode()

setNormalMode

public static void setNormalMode()

Set normal mode, including expression evaluation

setNormalMode

public static void setNormalMode(Context context)

Explicitly set the values for normal operation. Does not influence expression evaluation.

init

public static void init()

Ensure things have started - applications do not need call this. The method is public so any part of ARQ can call it. Note the final static initializer call

getContext

public static Context getContext()

set

public static void set(Symbol symbol,
                       boolean value)

setTrue

public static void setTrue(Symbol symbol)

setFalse

public static void setFalse(Symbol symbol)

unset

public static void unset(Symbol symbol)

isTrue

public static boolean isTrue(Symbol symbol)

isFalse

public static boolean isFalse(Symbol symbol)

isTrueOrUndef

public static boolean isTrueOrUndef(Symbol symbol)

isFalseOrUndef

public static boolean isFalseOrUndef(Symbol symbol)