org.h2.index.IndexLookupBatch Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.index;
import java.util.List;
import java.util.concurrent.Future;
import org.h2.result.SearchRow;
/**
* Support for asynchronous batched lookups in indexes. The flow is the
* following: H2 engine will be calling
* {@link #addSearchRows(SearchRow, SearchRow)} until method
* {@link #isBatchFull()} will return {@code true} or there are no more search
* rows to add. Then method {@link #find()} will be called to execute batched
* lookup. Note that a single instance of {@link IndexLookupBatch} can be reused
* for multiple sequential batched lookups, moreover it can be reused for
* multiple queries for the same prepared statement.
*
* @see Index#createLookupBatch(org.h2.table.TableFilter[], int)
* @author Sergi Vladykin
*/
public interface IndexLookupBatch {
/**
* Add search row pair to the batch.
*
* @param first the first row, or null for no limit
* @param last the last row, or null for no limit
* @return {@code false} if this search row pair is known to produce no
* results and thus the given row pair was not added
* @see Index#find(org.h2.table.TableFilter, SearchRow, SearchRow)
*/
boolean addSearchRows(SearchRow first, SearchRow last);
/**
* Check if this batch is full.
*
* @return {@code true} If batch is full, will not accept any
* more rows and {@link #find()} can be executed.
*/
boolean isBatchFull();
/**
* Execute batched lookup and return future cursor for each provided search
* row pair. Note that this method must return exactly the same number of
* future cursors in result list as number of
* {@link #addSearchRows(SearchRow, SearchRow)} calls has been done before
* {@link #find()} call exactly in the same order.
*
* @return List of future cursors for collected search rows.
*/
List> find();
/**
* Get plan for EXPLAIN.
*
* @return plan
*/
String getPlanSQL();
/**
* Reset this batch to clear state. This method will be called before and
* after each query execution.
*
* @param beforeQuery if it is being called before query execution
*/
void reset(boolean beforeQuery);
}