org.apache.drill.metastore.util

Class TableMetadataUtils

java.lang.Object

org.apache.drill.metastore.util.TableMetadataUtils

public class TableMetadataUtils
extends Object

Constructor Summary

Constructors

Constructor and Description
TableMetadataUtils()

Method Summary

Modifier and Type	Method and Description
static <T> Comparator<T>	getComparator(TypeProtos.MinorType type) Returns Comparator instance considering specified type.
static <T extends Comparable<T>> Comparator<T>	getNaturalNullsFirstComparator() Returns "natural order" comparator which threads nulls as min values.
static <T extends BaseMetadata> Map<SchemaPath,ColumnStatistics<?>>	mergeColumnsStatistics(Collection<T> metadataList, Set<SchemaPath> columns, List<CollectableColumnStatisticsKind<?>> statisticsToCollect) Merges list of specified metadata into the map of ColumnStatistics with columns as keys.
static TableMetadata	updateRowCount(TableMetadata tableMetadata, Collection<? extends BaseMetadata> statistics) Updates row count and column nulls count for specified table metadata and returns new TableMetadata instance with updated statistics.

Methods inherited from class java.lang.Object

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

Constructor Detail

TableMetadataUtils

public TableMetadataUtils()

Method Detail

getComparator

public static <T> Comparator<T> getComparator(TypeProtos.MinorType type)

Returns Comparator instance considering specified type.

Parameters:

type - type of the column

Returns:

Comparator instance

getNaturalNullsFirstComparator

public static <T extends Comparable<T>> Comparator<T> getNaturalNullsFirstComparator()

Returns "natural order" comparator which threads nulls as min values.

Type Parameters:

T - type to compare

Returns:

"natural order" comparator

mergeColumnsStatistics

public static <T extends BaseMetadata> Map<SchemaPath,ColumnStatistics<?>> mergeColumnsStatistics(Collection<T> metadataList,
                                                                                                  Set<SchemaPath> columns,
                                                                                                  List<CollectableColumnStatisticsKind<?>> statisticsToCollect)

Merges list of specified metadata into the map of ColumnStatistics with columns as keys.

Type Parameters:

T - type of metadata to collect

Parameters:

metadataList - list of metadata to be merged

columns - set of columns whose statistics should be merged

statisticsToCollect - kinds of statistics that should be collected

Returns:

list of merged metadata

updateRowCount

public static TableMetadata updateRowCount(TableMetadata tableMetadata,
                                           Collection<? extends BaseMetadata> statistics)

Updates row count and column nulls count for specified table metadata and returns new TableMetadata instance with updated statistics.

Parameters:

tableMetadata - table statistics to update

statistics - list of statistics whose row count should be considered

Returns:

new TableMetadata instance with updated statistics