com.orientechnologies.orient.core.sql.functions

Interface OSQLFunction

All Known Subinterfaces:

OIndexableSQLFunction, OSQLFunctionFiltered

All Known Implementing Classes:

ODatabaseFunction, OLuceneSearchFunctionTemplate, OLuceneSearchMoreLikeThisFunction, OLuceneSearchOnClassFunction, OLuceneSearchOnFieldsFunction, OLuceneSearchOnIndexFunction, OSpatialFunctionAbstract, OSpatialFunctionAbstractIndexable, OSQLFunctionAbsoluteValue, OSQLFunctionAbstract, OSQLFunctionAstar, OSQLFunctionAstar, OSQLFunctionAverage, OSQLFunctionBoth, OSQLFunctionBothE, OSQLFunctionBothV, OSQLFunctionCoalesce, OSQLFunctionConcat, OSQLFunctionConfigurableAbstract, OSQLFunctionCount, OSQLFunctionDate, OSQLFunctionDecimal, OSQLFunctionDecode, OSQLFunctionDifference, OSQLFunctionDijkstra, OSQLFunctionDijkstra, OSQLFunctionDistance, OSQLFunctionDistinct, OSQLFunctionDocument, OSQLFunctionEncode, OSQLFunctionEval, OSQLFunctionFirst, OSQLFunctionFormat, OSQLFunctionFormat, OSQLFunctionGremlin, OSQLFunctionHeuristicPathFinderAbstract, OSQLFunctionHeuristicPathFinderAbstract, OSQLFunctionIf, OSQLFunctionIfNull, OSQLFunctionIn, OSQLFunctionIndexKeySize, OSQLFunctionInE, OSQLFunctionIntersect, OSQLFunctionInterval, OSQLFunctionInV, OSQLFunctionLabel, OSQLFunctionLast, OSQLFunctionList, OSQLFunctionMap, OSQLFunctionMathAbstract, OSQLFunctionMax, OSQLFunctionMedian, OSQLFunctionMin, OSQLFunctionMode, OSQLFunctionMove, OSQLFunctionMoveFiltered, OSQLFunctionMultiValueAbstract, OSQLFunctionOut, OSQLFunctionOutE, OSQLFunctionOutV, OSQLFunctionPathFinder, OSQLFunctionPathFinder, OSQLFunctionPercentile, OSQLFunctionSequence, OSQLFunctionSet, OSQLFunctionShortestPath, OSQLFunctionShortestPath, OSQLFunctionStandardDeviation, OSQLFunctionStrcmpci, OSQLFunctionSum, OSQLFunctionSymmetricDifference, OSQLFunctionSysdate, OSQLFunctionThrowCME, OSQLFunctionTraversedEdge, OSQLFunctionTraversedElement, OSQLFunctionTraversedVertex, OSQLFunctionUnionAll, OSQLFunctionUUID, OSQLFunctionVariance, OSQLStaticReflectiveFunction, OSTAsBinaryFunction, OSTAsGeoJSONFunction, OSTAsTextFunction, OSTBufferFunction, OSTContainsFunction, OSTDisjointFunction, OSTDistanceFunction, OSTDistanceSphereFunction, OSTDWithinFunction, OSTEnvelopFunction, OSTEqualsFunction, OSTGeomFromGeoJSONFunction, OSTGeomFromTextFunction, OSTIntersectsFunction, OSTSrid, OSTWithinFunction

public interface OSQLFunction

Interface that defines a SQL Function. Functions can be state-less if registered as instance, or state-full when registered as class. State-less function are reused across queries, so don't keep any run-time information inside of it. State-full function, instead, stores Implement it and register it with: OSQLParser.getInstance().registerFunction() to being used by the SQL engine.

??? could it be possible to have a small piece of code here showing where to register a function using services ???

Author:

Luca Garulli (l.garulli--(at)--orientdb.com)

Method Summary

Modifier and Type	Method and Description
boolean	aggregateResults() A function can make calculation on several records before returning a result.
void	config(Object[] configuredParameters) Configure the function.
Object	execute(Object iThis, OIdentifiable iCurrentRecord, Object iCurrentResult, Object[] iParams, OCommandContext iContext) Process a record.
boolean	filterResult() A function can act both as transformation or filtering records.
int	getMaxParams() Maximum number of parameter this function can handle.
int	getMinParams() Minimum number of parameter this function must have.
String	getName() Function name, the name is used by the sql parser to identify a call this function.
Object	getResult() Only called when function aggregates results after all records have been passed to the function.
String	getSyntax() Returns a convenient SQL String representation of the function.
Object	mergeDistributedResult(List<Object> resultsToMerge) This method correspond to distributed query execution
void	setResult(Object iResult) Called by OCommandExecutor, given parameter is the number of results.
boolean	shouldMergeDistributedResult() This method correspond to distributed query execution

Method Detail

execute

Object execute(Object iThis,
               OIdentifiable iCurrentRecord,
               Object iCurrentResult,
               Object[] iParams,
               OCommandContext iContext)

Process a record.

Parameters:

iThis -

iCurrentRecord - : current record

iCurrentResult - TODO

iParams - : function parameters, number is ensured to be within minParams and maxParams.

iContext - : object calling this function

Returns:

function result, can be null. Special cases : can be null if function aggregate results, can be null if function filter results : this mean result is excluded

config

void config(Object[] configuredParameters)

Configure the function.

Parameters:

configuredParameters -

aggregateResults

boolean aggregateResults()

A function can make calculation on several records before returning a result.

Example of such function : sum, count, max, min ...

The final result of the aggregation is obtain by calling getResult()

Returns:

true if function aggregate results

filterResult

boolean filterResult()

A function can act both as transformation or filtering records. If the function may reduce the number final records than it must return true.

Function should return null for the execute method if the record must be excluded.

Returns:

true if the function acts as a record filter.

getName

String getName()

Function name, the name is used by the sql parser to identify a call this function.

Returns:

String , function name, never null or empty.

getMinParams

int getMinParams()

Minimum number of parameter this function must have.

Returns:

minimum number of parameters

getMaxParams

int getMaxParams()

Maximum number of parameter this function can handle.

Returns:

maximum number of parameters ??? -1 , negative or Integer.MAX_VALUE for unlimited ???

getSyntax

String getSyntax()

Returns a convenient SQL String representation of the function.

Example :

  myFunction( param1, param2, [optionalParam3])
 

This text will be used in exception messages.

Returns:

String , never null.

getResult

Object getResult()

Only called when function aggregates results after all records have been passed to the function.

Returns:

Aggregation result

setResult

void setResult(Object iResult)

Called by OCommandExecutor, given parameter is the number of results. ??? strange ???

Parameters:

iResult -

shouldMergeDistributedResult

boolean shouldMergeDistributedResult()

This method correspond to distributed query execution

Returns:

true if results that comes from different nodes need to be merged to obtain valid one, false otherwise

mergeDistributedResult

Object mergeDistributedResult(List<Object> resultsToMerge)

This method correspond to distributed query execution

Parameters:

resultsToMerge - is the results that comes from different nodes

Returns:

is the valid merged result