org.h2.index
Interface Index

All Superinterfaces:

DbObject, SchemaObject

All Known Subinterfaces:

RowIndex

All Known Implementing Classes:

BaseHashIndex, BaseIndex, BtreeIndex, FunctionIndex, HashIndex, LinkedIndex, MetaIndex, MultiVersionIndex, NonUniqueHashIndex, PageBtreeIndex, PageDataIndex, PageDelegateIndex, PageIndex, RangeIndex, ScanIndex, TreeIndex, ViewIndex

public interface Index
extends SchemaObject

An index. Indexes are used to speed up searching data.

Field Summary

static int

EMPTY_HEAD Indicates that there is no head record yet.

Fields inherited from interface org.h2.engine.DbObject

AGGREGATE, COMMENT, CONSTANT, CONSTRAINT, FUNCTION_ALIAS, INDEX, RIGHT, ROLE, SCHEMA, SEQUENCE, SETTING, TABLE_OR_VIEW, TRIGGER, USER, USER_DATATYPE

Method Summary

void	add(Session session, Row row) Add a row to the index.
boolean	canFindNext() Check if the index can get the next higher value.
boolean	canGetFirstOrLast() Check if the index can directly look up the lowest or highest value of a column.
void	close(Session session) Close this index.
void	commit(int operation, Row row) Commit the operation for a row.
int	compareKeys(SearchRow rowData, SearchRow compare) Compare the positions of two rows.
int	compareRows(SearchRow rowData, SearchRow compare) Compare two rows.
boolean	containsNullAndAllowMultipleNull(SearchRow newRow) Check if one of the columns is NULL and multiple rows with NULL are allowed using the current compatibility mode for unique indexes.
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.
Cursor	findFirstOrLast(Session session, boolean first) Find the lowest or highest value of a column.
Cursor	findNext(Session session, SearchRow higherThan, SearchRow last) Find a row or a list of rows that is larger and create a cursor to iterate over the result.
int	getColumnIndex(Column col) Get the index of a column in the list of index columns
java.lang.String	getColumnListSQL() Get the list of columns as a string.
Column[]	getColumns() Get the indexed columns.
double	getCost(Session session, int[] masks) Estimate the cost to search for rows given the search mask.
long	getCostRangeIndex(int[] masks, long rowCount) Estimate the cost required to search one row, and then iterate over the given number of rows.
java.sql.SQLException	getDuplicateKeyException() Create a duplicate key exception with a message that contains the index name
IndexColumn[]	getIndexColumns() Get the indexed columns as index columns (with ordering information).
IndexType	getIndexType() Get the index type.
int	getLookupCost(long rowCount) Estimate the cost required to search a number of rows.
java.lang.String	getPlanSQL() Get the message to show in a EXPLAIN statement.
int	getRootPageId() Get the root page of this index.
long	getRowCount(Session session) Get the row count of this table, for the given session.
long	getRowCountApproximation() Get the approximated row count for this table.
Table	getTable() Get the table on which this index is based.
boolean	needRebuild() Check if the index needs to be rebuilt.
void	remove(Session session) Remove the index.
void	remove(Session session, Row row) Remove a row from the index.
void	truncate(Session session) Remove all rows from the index.

Methods inherited from interface org.h2.schema.SchemaObject

getSchema

Methods inherited from interface org.h2.engine.DbObject

checkRename, getChildren, getComment, getCreateSQL, getCreateSQLForCopy, getDatabase, getDropSQL, getHeadPos, getId, getModificationId, getName, getSQL, getType, isTemporary, removeChildrenAndResources, rename, setComment, setModified, setTemporary

Field Detail

EMPTY_HEAD

static final int EMPTY_HEAD

Indicates that there is no head record yet.

See Also:

Constant Field Values

Method Detail

getDuplicateKeyException

java.sql.SQLException getDuplicateKeyException()

Create a duplicate key exception with a message that contains the index name

Returns:

the exception

getPlanSQL

java.lang.String getPlanSQL()

Get the message to show in a EXPLAIN statement.

Returns:

the plan

close

void close(Session session)
           throws java.sql.SQLException

Close this index.

Parameters:

session - the session used to write data

Throws:

java.sql.SQLException

add

void add(Session session,
         Row row)
         throws java.sql.SQLException

Add a row to the index.

Parameters:

session - the session to use

row - the data

Throws:

java.sql.SQLException

remove

void remove(Session session,
            Row row)
            throws java.sql.SQLException

Remove a row from the index.

Parameters:

session - the session

row - the data

Throws:

java.sql.SQLException

find

Cursor find(Session session,
            SearchRow first,
            SearchRow last)
            throws java.sql.SQLException

Find a row or a list of rows and create a cursor to iterate over the result.

Parameters:

session - the session

first - the first row, or null for no limit

last - the last row, or null for no limit

Returns:

the cursor

Throws:

java.sql.SQLException

getCost

double getCost(Session session,
               int[] masks)
               throws java.sql.SQLException

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.

Parameters:

session - the session

masks - the search mask

Returns:

the estimated cost

Throws:

java.sql.SQLException

remove

void remove(Session session)
            throws java.sql.SQLException

Remove the index.

Parameters:

session - the session

Throws:

java.sql.SQLException

truncate

void truncate(Session session)
              throws java.sql.SQLException

Remove all rows from the index.

Parameters:

session - the session

Throws:

java.sql.SQLException

canGetFirstOrLast

boolean canGetFirstOrLast()

Check if the index can directly look up the lowest or highest value of a column.

Returns:

true if it can

canFindNext

boolean canFindNext()

Check if the index can get the next higher value.

Returns:

true if it can

findNext

Cursor findNext(Session session,
                SearchRow higherThan,
                SearchRow last)
                throws java.sql.SQLException

Find a row or a list of rows that is larger and create a cursor to iterate over the result.

Parameters:

session - the session

higherThan - the lower limit (excluding)

last - the last row, or null for no limit

Returns:

the cursor

Throws:

java.sql.SQLException

findFirstOrLast

Cursor findFirstOrLast(Session session,
                       boolean first)
                       throws java.sql.SQLException

Find the lowest or highest value of a column.

Parameters:

session - the session

first - true if the first (lowest for ascending indexes) or last value should be returned

Returns:

a cursor or null

Throws:

java.sql.SQLException

needRebuild

boolean needRebuild()

Check if the index needs to be rebuilt. This method is called after opening an index.

Returns:

true if a rebuild is required.

getRowCount

long getRowCount(Session session)

Get the row count of this table, for the given session.

Parameters:

session - the session

Returns:

the row count

getRowCountApproximation

long getRowCountApproximation()

Get the approximated row count for this table.

Returns:

the approximated row count

getLookupCost

int getLookupCost(long rowCount)

Estimate the cost required to search a number of rows.

Parameters:

rowCount - the row count

Returns:

the estimated cost

getCostRangeIndex

long getCostRangeIndex(int[] masks,
                       long rowCount)
                       throws java.sql.SQLException

Estimate the cost required to search one row, and then iterate over the given number of rows.

Parameters:

masks - the search mask

rowCount - the row count

Returns:

the estimated cost

Throws:

java.sql.SQLException

compareRows

int compareRows(SearchRow rowData,
                SearchRow compare)
                throws java.sql.SQLException

Compare two rows.

Parameters:

rowData - the first row

compare - the second row

Returns:

0 if both rows are equal, -1 if the first row is smaller, otherwise 1

Throws:

java.sql.SQLException

containsNullAndAllowMultipleNull

boolean containsNullAndAllowMultipleNull(SearchRow newRow)

Check if one of the columns is NULL and multiple rows with NULL are allowed using the current compatibility mode for unique indexes. Note: NULL behavior is complicated in SQL.

Parameters:

newRow - the row to check

Returns:

true if one of the columns is null and multiple nulls in unique indexes are allowed

compareKeys

int compareKeys(SearchRow rowData,
                SearchRow compare)

Compare the positions of two rows.

Parameters:

rowData - the first row

compare - the second row

Returns:

0 if both rows are equal, -1 if the first row is smaller, otherwise 1

getColumnIndex

int getColumnIndex(Column col)

Get the index of a column in the list of index columns

Parameters:

col - the column

Returns:

the index (0 meaning first column)

getColumnListSQL

java.lang.String getColumnListSQL()

Get the list of columns as a string.

Returns:

the list of columns

getIndexColumns

IndexColumn[] getIndexColumns()

Get the indexed columns as index columns (with ordering information).

Returns:

the index columns

getColumns

Column[] getColumns()

Get the indexed columns.

Returns:

the columns

getIndexType

IndexType getIndexType()

Get the index type.

Returns:

the index type

getTable

Table getTable()

Get the table on which this index is based.

Returns:

the table

commit

void commit(int operation,
            Row row)
            throws java.sql.SQLException

Commit the operation for a row. This is only important for multi-version indexes.

Parameters:

operation - the operation type

row - the row

Throws:

java.sql.SQLException

getRootPageId

int getRootPageId()

Get the root page of this index.

Returns:

the root page id