Package org.apache.flink.cdc.common.utils

Class SchemaUtils

java.lang.Object

org.apache.flink.cdc.common.utils.SchemaUtils

@PublicEvolving
public class SchemaUtils
extends Object

Utils for Schema to perform the ability of evolution.

Constructor Summary

Constructors

Constructor	Description
SchemaUtils()

Method Summary

Modifier and Type	Method	Description
static Schema	applySchemaChangeEvent(Schema schema, SchemaChangeEvent event)	apply SchemaChangeEvent to the old schema and return the schema after changing.
static List<RecordData.FieldGetter>	createFieldGetters(List<Column> columns)	create a list of RecordData.FieldGetter from given Column to get Object from RecordData.
static List<RecordData.FieldGetter>	createFieldGetters(Schema schema)	create a list of RecordData.FieldGetter from given Schema to get Object from RecordData.
static List<RecordData.FieldGetter>	createFieldGetters(DataType[] dataTypes)	create a list of RecordData.FieldGetter from given Column to get Object from RecordData.
static Schema	ensurePkNonNull(Schema schema)
static int	getNumericPrecision(DataType dataType)	Deprecated.
static Column	inferWiderColumn(Column lColumn, Column rColumn)	Deprecated. Use getLeastCommonType in SchemaMergingUtils instead.
static Schema	inferWiderSchema(List<Schema> schemas)	Deprecated. Use getCommonSchema in SchemaMergingUtils instead.
static Schema	inferWiderSchema(Schema lSchema, Schema rSchema)	Deprecated. Use getLeastCommonSchema in SchemaMergingUtils instead.
static DataType	inferWiderType(DataType lType, DataType rType)	Deprecated. Use getLeastCommonType in SchemaMergingUtils instead.
static boolean	isSchemaChangeEventRedundant(Schema currentSchema, SchemaChangeEvent event)	This function checks if the given schema change event has been applied already.
static List<Object>	restoreOriginalData(RecordData recordData, List<RecordData.FieldGetter> fieldGetters)	Restore original data fields from RecordData structure.
static Optional<SchemaChangeEvent>	transformSchemaChangeEvent(boolean hasAsterisk, List<String> referencedColumns, SchemaChangeEvent event)	This function determines if the given schema change event event should be sent to downstream based on if the given transform rule has asterisk, and what columns are referenced.

Methods inherited from class java.lang.Object

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

Constructor Detail

SchemaUtils

public SchemaUtils()

Method Detail

createFieldGetters

@CheckReturnValue
public static List<RecordData.FieldGetter> createFieldGetters(Schema schema)

create a list of RecordData.FieldGetter from given Schema to get Object from RecordData.

createFieldGetters

@CheckReturnValue
public static List<RecordData.FieldGetter> createFieldGetters(List<Column> columns)

create a list of RecordData.FieldGetter from given Column to get Object from RecordData.

createFieldGetters

@CheckReturnValue
public static List<RecordData.FieldGetter> createFieldGetters(DataType[] dataTypes)

create a list of RecordData.FieldGetter from given Column to get Object from RecordData.

restoreOriginalData

@CheckReturnValue
public static List<Object> restoreOriginalData(@Nullable
                                               RecordData recordData,
                                               List<RecordData.FieldGetter> fieldGetters)

Restore original data fields from RecordData structure.

applySchemaChangeEvent

@CheckReturnValue
public static Schema applySchemaChangeEvent(Schema schema,
                                            SchemaChangeEvent event)

apply SchemaChangeEvent to the old schema and return the schema after changing.

transformSchemaChangeEvent

@CheckReturnValue
public static Optional<SchemaChangeEvent> transformSchemaChangeEvent(boolean hasAsterisk,
                                                                     List<String> referencedColumns,
                                                                     SchemaChangeEvent event)

This function determines if the given schema change event event should be sent to downstream based on if the given transform rule has asterisk, and what columns are referenced.

For example, if hasAsterisk is false, then all AddColumnEvent and DropColumnEvent should be ignored since asterisk-less transform should not emit schema change events that change number of downstream columns.

Also, referencedColumns will be used to determine if the schema change event affects any referenced columns, since if a column has been projected out of downstream, its corresponding schema change events should not be emitted, either.

For the case when hasAsterisk is true, things will be cleaner since we don't have to filter out any schema change events. All we need to do is to change AddColumnEvent's inserting position, and replacing `FIRST` / `LAST` with column-relative position indicators. This is necessary since extra calculated columns might be added, and `FIRST` / `LAST` position might differ.

isSchemaChangeEventRedundant

public static boolean isSchemaChangeEventRedundant(@Nullable
                                                   Schema currentSchema,
                                                   SchemaChangeEvent event)

This function checks if the given schema change event has been applied already. If so, it will be ignored to avoid sending duplicate evolved schema change events to sink metadata applier.

ensurePkNonNull

@CheckReturnValue
public static Schema ensurePkNonNull(Schema schema)

inferWiderSchema

@Deprecated
public static Schema inferWiderSchema(List<Schema> schemas)

Deprecated.

Use getCommonSchema in SchemaMergingUtils instead.

Merge compatible schemas.

inferWiderSchema

@Deprecated
@VisibleForTesting
public static Schema inferWiderSchema(@Nullable
                                      Schema lSchema,
                                      Schema rSchema)

Deprecated.

Use getLeastCommonSchema in SchemaMergingUtils instead.

Try to combine two schemas with potential incompatible type.

inferWiderColumn

@Deprecated
@VisibleForTesting
public static Column inferWiderColumn(Column lColumn,
                                      Column rColumn)

Deprecated.

Use getLeastCommonType in SchemaMergingUtils instead.

Try to combine two columns with potential incompatible type.

inferWiderType

@Deprecated
@VisibleForTesting
public static DataType inferWiderType(DataType lType,
                                      DataType rType)

Deprecated.

Use getLeastCommonType in SchemaMergingUtils instead.

Try to combine given data types to a compatible wider data type.

getNumericPrecision

@Deprecated
@VisibleForTesting
public static int getNumericPrecision(DataType dataType)

Deprecated.