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

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object obj)`
`static String`	`getAutoIncrementingColumnName()` Get the name of the auto-incrementing column
`static Type`	`getAutoIncrementingColumnType()` Get the type of the auto-incrementing column
`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`	`hasAutoIncrementingColumn()` Tells if there's auto-incrementing column
`boolean`	`hasColumn(String columnName)` Returns true if the column exists.
`boolean`	`hasColumnIds()` Tells whether this schema includes IDs for columns.
`int`	`hashCode()`
`boolean`	`hasImmutableColumns()` Tells if there's at least one immutable column
`boolean`	`hasNullableColumns()` Tells if there's at least one nullable column
`boolean`	`isPrimaryKeyUnique()` Answers if the primary key is unique for the table
`PartialRow`	`newPartialRow()` Creates a new partial row for the schema.

Methods inherited from class java.lang.Object
clone, finalize, getClass, 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.
  - isPrimaryKeyUnique
```
public boolean isPrimaryKeyUnique()
```
    Answers if the primary key is unique for the table
    
    Returns:
    
    true if the key is unique
  - hasAutoIncrementingColumn
```
public boolean hasAutoIncrementingColumn()
```
    Tells if there's auto-incrementing column
    
    Returns:
    
    true if there's auto-incrementing column, else false.
  - getAutoIncrementingColumnName
```
public static String getAutoIncrementingColumnName()
```
    Get the name of the auto-incrementing column
    
    Returns:
    
    column name of the auto-incrementing column.
  - getAutoIncrementingColumnType
```
public static Type getAutoIncrementingColumnType()
```
    Get the type of the auto-incrementing column
    
    Returns:
    
    type of the auto-incrementing column.
  - 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.
  - hasImmutableColumns
```
public boolean hasImmutableColumns()
```
    Tells if there's at least one immutable column
    
    Returns:
    
    true if at least one column is immutable, 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
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object

Class Schema

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Schema

Schema

Method Detail

getColumns

getVarLengthColumnCount

getRowSize

getColumnOffset

hasColumn

getColumnIndex

getColumnIndex

getColumnByIndex

getColumn

getColumnCount

getPrimaryKeyColumnCount

getPrimaryKeyColumns

isPrimaryKeyUnique

hasAutoIncrementingColumn

getAutoIncrementingColumnName

getAutoIncrementingColumnType

getRowKeyProjection

hasNullableColumns

hasImmutableColumns

hasColumnIds

newPartialRow

equals

hashCode