gate.mimir.search.query

Interface QueryExecutor

All Superinterfaces:

it.unimi.di.big.mg4j.search.DocumentIterator

All Known Implementing Classes:

AbstractIntersectionQueryExecutor, AbstractOverlapQuery.OverlapQueryExecutor, AbstractQueryExecutor, AndQuery.AndQueryExecutor, AnnotationQuery.AnnotationQueryExecutor, ConstQuery.ConstQueryExecutor, GapQuery.GapQueryExecutor, MinusQuery.MinusQueryExecutor, OrQuery.OrQueryExecutor, RepeatsQuery.RepeatsQueryExecutor, SequenceQuery.SequenceQueryExecutor, TermQuery.TermQueryExecutor

public interface QueryExecutor
extends it.unimi.di.big.mg4j.search.DocumentIterator

A query executor is capable of running a query (represented as a tree of QueryNodes over a set of indexes.

Field Summary

Fields inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

END_OF_LIST

Method Summary

Modifier and Type	Method and Description
void	close() Closes this QueryExecutor and releases all resources used.
long	getLatestDocument() Returns the value returned by the most recent call to #nextDocument(int).
QueryEngine	getQueryEngine() Gets the QueryEngine that has created this query executor.
QueryNode	getQueryNode() Gets that QueryNode representing the query being executed.
long	nextDocument(long greaterThan) Gets the next document that contains a match, with a document ID greater than the ID provided in the from parameter.
Binding	nextHit() Gets the next matching position, in the document last returned by DocumentIterator.nextDocument().

Methods inherited from interface it.unimi.di.big.mg4j.search.DocumentIterator

accept, acceptOnTruePaths, dispose, document, indices, intervalIterator, intervalIterator, intervalIterators, mayHaveNext, nextDocument, skipTo, weight, weight

Method Detail

nextDocument

long nextDocument(long greaterThan)
           throws IOException

Gets the next document that contains a match, with a document ID greater than the ID provided in the from parameter. This method essentially requests the query executor to skip over a number of documents that are not desired for external reasons (e.g. when running a complex query, other query constraints may have already removed a set of documents from the candidate list). The query executor will never roll back: all document IDs returned are in ascending order. This means that if the value provided for the greaterThan parameter is lower than the latest document ID returned, it will have no effect.

Parameters:

greaterThan - a document ID representing the lowest bound (exclusive) for the requested document ID.

Returns:

the matching document ID, or -1 if no more documents match the query. The returned value will be strictly greater than greaterThan, or -1 if no more matching documents are found.

Throws:

IOException - if the index files cannot be accessed.

getLatestDocument

long getLatestDocument()

Returns the value returned by the most recent call to #nextDocument(int).

Returns:

an int value.

nextHit

Binding nextHit()
         throws IOException

Gets the next matching position, in the document last returned by DocumentIterator.nextDocument(). Hits are always returned in increasing order of start offset, but hits that start at the same place may be returned in any order (i.e. not necessarily longest first or shortest first).

Returns:

the Binding corresponding to the root query node for this executor. If no further matches are possible on the current document, then null is returned.

Throws:

IOException - if the index files cannot be accessed.

close

void close()
    throws IOException

Closes this QueryExecutor and releases all resources used.

Throws:

IOException - if the index files cannot be accessed.

getQueryEngine

QueryEngine getQueryEngine()

Gets the QueryEngine that has created this query executor.

Returns:

getQueryNode

QueryNode getQueryNode()

Gets that QueryNode representing the query being executed.

Returns: