org.apache.iceberg

Class Schema

java.lang.Object

org.apache.iceberg.Schema

All Implemented Interfaces:

java.io.Serializable

public class Schema
extends java.lang.Object
implements java.io.Serializable

The schema of a data table.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Schema(java.util.List<Types.NestedField> columns)
Schema(java.util.List<Types.NestedField> columns, java.util.Map<java.lang.String,java.lang.Integer> aliases)
Schema(Types.NestedField... columns)

Method Summary

Modifier and Type	Method and Description
Accessor<StructLike>	accessorForField(int id) Returns an accessor for retrieving the data from StructLike.
java.lang.Integer	aliasToId(java.lang.String alias) Returns the column id for the given column alias.
Types.StructType	asStruct() Returns the underlying struct type for this schema.
Types.NestedField	caseInsensitiveFindField(java.lang.String name) Returns a sub-field by name as a Types.NestedField.
Schema	caseInsensitiveSelect(java.util.Collection<java.lang.String> names) Creates a projection schema for a subset of columns, selected by case insensitive names
Schema	caseInsensitiveSelect(java.lang.String... names) Creates a projection schema for a subset of columns, selected by case insensitive names
java.util.List<Types.NestedField>	columns() Returns a List of the columns in this Schema.
java.lang.String	findColumnName(int id) Returns the full column name for the given id.
Types.NestedField	findField(int id) Returns the sub-field identified by the field id as a Types.NestedField.
Types.NestedField	findField(java.lang.String name) Returns a sub-field by name as a Types.NestedField.
Type	findType(int id) Returns the Type of a sub-field identified by the field id.
Type	findType(java.lang.String name) Returns the Type of a sub-field identified by the field name.
java.util.Map<java.lang.String,java.lang.Integer>	getAliases() Returns an alias map for this schema, if set.
java.lang.String	idToAlias(java.lang.Integer fieldId) Returns the full column name in the unconverted data schema for the given column id.
Schema	select(java.util.Collection<java.lang.String> names) Creates a projection schema for a subset of columns, selected by name.
Schema	select(java.lang.String... names) Creates a projection schema for a subset of columns, selected by name.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Schema

public Schema(java.util.List<Types.NestedField> columns,
              java.util.Map<java.lang.String,java.lang.Integer> aliases)

Schema

public Schema(java.util.List<Types.NestedField> columns)

Schema

public Schema(Types.NestedField... columns)

Method Detail

getAliases

public java.util.Map<java.lang.String,java.lang.Integer> getAliases()

Returns an alias map for this schema, if set.

Alias maps are created when translating an external schema, like an Avro Schema, to this format. The original column names can be provided in a Map when constructing this Schema.

Returns:

a Map of column aliases to field ids

asStruct

public Types.StructType asStruct()

Returns the underlying struct type for this schema.

Returns:

the StructType version of this schema.

columns

public java.util.List<Types.NestedField> columns()

Returns a List of the columns in this Schema.

findType

public Type findType(java.lang.String name)

Returns the Type of a sub-field identified by the field name.

Parameters:

name - a field name

Returns:

a Type for the sub-field or null if it is not found

findType

public Type findType(int id)

Returns the Type of a sub-field identified by the field id.

Parameters:

id - a field id

Returns:

a Type for the sub-field or null if it is not found

findField

public Types.NestedField findField(int id)

Returns the sub-field identified by the field id as a Types.NestedField.

Parameters:

id - a field id

Returns:

the sub-field or null if it is not found

findField

public Types.NestedField findField(java.lang.String name)

Returns a sub-field by name as a Types.NestedField.

The result may be a top-level or a nested field.

Parameters:

name - a String name

Returns:

a Type for the sub-field or null if it is not found

caseInsensitiveFindField

public Types.NestedField caseInsensitiveFindField(java.lang.String name)

Returns a sub-field by name as a Types.NestedField.

The result may be a top-level or a nested field.

Parameters:

name - a String name

Returns:

the sub-field or null if it is not found

findColumnName

public java.lang.String findColumnName(int id)

Returns the full column name for the given id.

Parameters:

id - a field id

Returns:

the full column name in this schema that resolves to the id

aliasToId

public java.lang.Integer aliasToId(java.lang.String alias)

Returns the column id for the given column alias. Column aliases are set by conversions from Parquet or Avro to this Schema type.

Parameters:

alias - a full column name in the unconverted data schema

Returns:

the column id in this schema, or null if the column wasn't found

idToAlias

public java.lang.String idToAlias(java.lang.Integer fieldId)

Returns the full column name in the unconverted data schema for the given column id. Column aliases are set by conversions from Parquet or Avro to this Schema type.

Parameters:

fieldId - a column id in this schema

Returns:

the full column name in the unconverted data schema, or null if one wasn't found

accessorForField

public Accessor<StructLike> accessorForField(int id)

Returns an accessor for retrieving the data from StructLike.

Accessors do not retrieve data contained in lists or maps.

Parameters:

id - a column id in this schema

Returns:

an Accessor to retrieve values from a StructLike row

select

public Schema select(java.lang.String... names)

Creates a projection schema for a subset of columns, selected by name.

Names that identify nested fields will select part or all of the field's top-level column.

Parameters:

names - String names for selected columns

Returns:

a projection schema from this schema, by name

select

public Schema select(java.util.Collection<java.lang.String> names)

Creates a projection schema for a subset of columns, selected by name.

Names that identify nested fields will select part or all of the field's top-level column.

Parameters:

names - a List of String names for selected columns

Returns:

a projection schema from this schema, by name

caseInsensitiveSelect

public Schema caseInsensitiveSelect(java.lang.String... names)

Creates a projection schema for a subset of columns, selected by case insensitive names

Names that identify nested fields will select part or all of the field's top-level column.

Parameters:

names - a List of String names for selected columns

Returns:

a projection schema from this schema, by names

caseInsensitiveSelect

public Schema caseInsensitiveSelect(java.util.Collection<java.lang.String> names)

Creates a projection schema for a subset of columns, selected by case insensitive names

Names that identify nested fields will select part or all of the field's top-level column.

Parameters:

names - a List of String names for selected columns

Returns:

a projection schema from this schema, by names

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object