org.apache.kudu

Class Schema

java.lang.Object

org.apache.kudu.Schema

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class Schema
extends Object

Represents table's schema which is essentially a list of columns. This class offers a few utility methods for querying it.

Constructor Summary

Constructors

Constructor and Description
Schema(List<ColumnSchema> columns) Constructs a schema using the specified columns and does some internal accounting
Schema(List<ColumnSchema> columns, List<Integer> columnIds) Constructs a schema using the specified columns and IDs.

Method Summary

Modifier and Type	Method and Description
ColumnSchema	getColumn(String columnName) Get the column associated with the specified name
ColumnSchema	getColumnByIndex(int idx) Get the column at the specified index in the original list
int	getColumnCount() Get the count of columns in this schema
int	getColumnIndex(int columnId) Get the column index of the column with the provided ID.
int	getColumnIndex(String columnName) Get the index for the provided column name.
int	getColumnOffset(int idx) Get the index at which this column can be found in the backing byte array
List<ColumnSchema>	getColumns() Get the list of columns used to create this schema
int	getPrimaryKeyColumnCount() Get the count of columns that are part of the primary key.
List<ColumnSchema>	getPrimaryKeyColumns() Get the primary key columns.
Schema	getRowKeyProjection() Get a schema that only contains the columns which are part of the key
int	getRowSize() Get the size a row built using this schema would be
int	getVarLengthColumnCount() Get the count of columns with variable length (BINARY/STRING) in this schema.
boolean	hasColumn(String columnName) Returns true if the column exists.
boolean	hasColumnIds() Tells whether this schema includes IDs for columns.
boolean	hasNullableColumns() Tells if there's at least one nullable column
PartialRow	newPartialRow() Creates a new partial row for the schema.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Schema

public Schema(List<ColumnSchema> columns)

Constructs a schema using the specified columns and does some internal accounting

Parameters:

columns - the columns in index order See ColumnPBsToSchema() in src/kudu/common/wire_protocol.cc

Schema

public Schema(List<ColumnSchema> columns,
              List<Integer> columnIds)

Constructs a schema using the specified columns and IDs. This is not a stable API, prefer using Schema(List) to create a new schema.

Parameters:

columns - the columns in index order

columnIds - the column ids of the provided columns, or null

Throws:

IllegalArgumentException - If the column ids length does not match the columns length See ColumnPBsToSchema() in src/kudu/common/wire_protocol.cc

Method Detail

getColumns

public List<ColumnSchema> getColumns()

Get the list of columns used to create this schema

Returns:

list of columns

getVarLengthColumnCount

public int getVarLengthColumnCount()

Get the count of columns with variable length (BINARY/STRING) in this schema.

Returns:

strings count

getRowSize

public int getRowSize()

Get the size a row built using this schema would be

Returns:

size in bytes

getColumnOffset

public int getColumnOffset(int idx)

Get the index at which this column can be found in the backing byte array

Parameters:

idx - column's index

Returns:

column's offset

hasColumn

public boolean hasColumn(String columnName)

Returns true if the column exists.

Parameters:

columnName - column to search for

Returns:

true if the column exists

getColumnIndex

public int getColumnIndex(String columnName)

Get the index for the provided column name.

Parameters:

columnName - column to search for

Returns:

an index in the schema

getColumnIndex

public int getColumnIndex(int columnId)

Get the column index of the column with the provided ID. This method is not part of the stable API.

Parameters:

columnId - the column id of the column

Returns:

the column index of the column.

getColumnByIndex

public ColumnSchema getColumnByIndex(int idx)

Get the column at the specified index in the original list

Parameters:

idx - column's index

Returns:

the column

getColumn

public ColumnSchema getColumn(String columnName)

Get the column associated with the specified name

Parameters:

columnName - column's name

Returns:

the column

getColumnCount

public int getColumnCount()

Get the count of columns in this schema

Returns:

count of columns

getPrimaryKeyColumnCount

public int getPrimaryKeyColumnCount()

Get the count of columns that are part of the primary key.

Returns:

count of primary key columns.

getPrimaryKeyColumns

public List<ColumnSchema> getPrimaryKeyColumns()

Get the primary key columns.

Returns:

the primary key columns.

getRowKeyProjection

public Schema getRowKeyProjection()

Get a schema that only contains the columns which are part of the key

Returns:

new schema with only the keys

hasNullableColumns

public boolean hasNullableColumns()

Tells if there's at least one nullable column

Returns:

true if at least one column is nullable, else false.

hasColumnIds

public boolean hasColumnIds()

Tells whether this schema includes IDs for columns. A schema created by a client as part of table creation will not include IDs, but schemas for open tables will include IDs. This method is not part of the stable API.

Returns:

whether this schema includes column IDs.

newPartialRow

public PartialRow newPartialRow()

Creates a new partial row for the schema.

Returns:

a new partial row