/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.index;
import org.h2.engine.Session;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.schema.SchemaObject;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.table.TableFilter;
/**
* An index. Indexes are used to speed up searching data.
*/
public interface Index extends SchemaObject {
/**
* Get the message to show in a EXPLAIN statement.
*
* @return the plan
*/
String getPlanSQL();
/**
* Close this index.
*
* @param session the session used to write data
*/
void close(Session session);
/**
* Add a row to the index.
*
* @param session the session to use
* @param row the row to add
*/
void add(Session session, Row row);
/**
* Remove a row from the index.
*
* @param session the session
* @param row the row
*/
void remove(Session session, Row row);
/**
* Find a row or a list of rows and create a cursor to iterate over the result.
*
* @param session the session
* @param first the first row, or null for no limit
* @param last the last row, or null for no limit
* @return the cursor to iterate over the results
*/
Cursor find(Session session, SearchRow first, SearchRow last);
/**
* Find a row or a list of rows and create a cursor to iterate over the result.
*
* @param filter the table filter (which possibly knows
* about additional conditions)
* @param first the first row, or null for no limit
* @param last the last row, or null for no limit
* @return the cursor to iterate over the results
*/
Cursor find(TableFilter filter, SearchRow first, SearchRow last);
/**
* Estimate the cost to search for rows given the search mask.
* There is one element per column in the search mask.
* For possible search masks, see IndexCondition.
*
* @param session the session
* @param masks the search mask
* @return the estimated cost
*/
double getCost(Session session, int[] masks);
/**
* Remove the index.
*
* @param session the session
*/
void remove(Session session);
/**
* Remove all rows from the index.
*
* @param session the session
*/
void truncate(Session session);
/**
* Check if the index can directly look up the lowest or highest value of a
* column.
*
* @return true if it can
*/
boolean canGetFirstOrLast();
/**
* Check if the index can get the next higher value.
*
* @return true if it can
*/
boolean canFindNext();
/**
* Find a row or a list of rows that is larger and create a cursor to
* iterate over the result.
*
* @param session the session
* @param higherThan the lower limit (excluding)
* @param last the last row, or null for no limit
* @return the cursor
*/
Cursor findNext(Session session, SearchRow higherThan, SearchRow last);
/**
* Find the first (or last) value of this index. The cursor returned is
* positioned on the correct row, or on null if no row has been found.
*
* @param session the session
* @param first true if the first (lowest for ascending indexes) or last
* value should be returned
* @return a cursor (never null)
*/
Cursor findFirstOrLast(Session session, boolean first);
/**
* Check if the index needs to be rebuilt.
* This method is called after opening an index.
*
* @return true if a rebuild is required.
*/
boolean needRebuild();
/**
* Get the row count of this table, for the given session.
*
* @param session the session
* @return the row count
*/
long getRowCount(Session session);
/**
* Get the approximated row count for this table.
*
* @return the approximated row count
*/
long getRowCountApproximation();
/**
* Compare two rows.
*
* @param rowData the first row
* @param compare the second row
* @return 0 if both rows are equal, -1 if the first row is smaller, otherwise 1
*/
int compareRows(SearchRow rowData, SearchRow compare);
/**
* Get the index of a column in the list of index columns
*
* @param col the column
* @return the index (0 meaning first column)
*/
int getColumnIndex(Column col);
/**
* Get the indexed columns as index columns (with ordering information).
*
* @return the index columns
*/
IndexColumn[] getIndexColumns();
/**
* Get the indexed columns.
*
* @return the columns
*/
Column[] getColumns();
/**
* Get the index type.
*
* @return the index type
*/
IndexType getIndexType();
/**
* Get the table on which this index is based.
*
* @return the table
*/
Table getTable();
/**
* Commit the operation for a row. This is only important for multi-version
* indexes.
*
* @param operation the operation type
* @param row the row
*/
void commit(int operation, Row row);
/**
* Get the row with the given key.
*
* @param session the session
* @param key the unique key
* @return the row
*/
Row getRow(Session session, long key);
/**
* Does this index support lookup by row id?
*
* @return true if it does
*/
boolean isRowIdIndex();
/**
* Can this index iterate over all rows?
*
* @return true if it can
*/
boolean canScan();
/**
* Enable or disable the 'sorted insert' optimizations (rows are inserted in
* ascending or descending order) if applicable for this index
* implementation.
*
* @param sortedInsertMode the new value
*/
void setSortedInsertMode(boolean sortedInsertMode);
}