org.apache.drill.exec.store.hive

Class ColumnListsCache

java.lang.Object

org.apache.drill.exec.store.hive.ColumnListsCache

public class ColumnListsCache
extends Object

The class represents "cache" for partition and table columns. Used to reduce physical plan for Hive tables. Only unique partition lists of columns stored in the column lists cache. Table columns should be stored at index 0.

Constructor Summary

Constructors

Constructor and Description
ColumnListsCache()
ColumnListsCache(org.apache.hadoop.hive.metastore.api.Table table)

Method Summary

Modifier and Type	Method and Description
int	addOrGet(List<org.apache.hadoop.hive.metastore.api.FieldSchema> columns) Checks if column list has been added before and returns position of column list.
List<org.apache.hadoop.hive.metastore.api.FieldSchema>	getColumns(int index) Returns list of columns at the specified position in fields list, or null if index is negative or greater than fields list size.
List<List<org.apache.hadoop.hive.metastore.api.FieldSchema>>	getFields()
List<org.apache.hadoop.hive.metastore.api.FieldSchema>	getTableSchemaColumns() Safely retrieves Hive table columns from cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

ColumnListsCache

public ColumnListsCache(org.apache.hadoop.hive.metastore.api.Table table)

ColumnListsCache

public ColumnListsCache()

Method Detail

addOrGet

public int addOrGet(List<org.apache.hadoop.hive.metastore.api.FieldSchema> columns)

Checks if column list has been added before and returns position of column list. If list is unique, adds list to the fields list and returns it position. Returns -1, if equals null.

Parameters:

columns - list of columns

Returns:

index of or -1, if equals null

getColumns

public List<org.apache.hadoop.hive.metastore.api.FieldSchema> getColumns(int index)

Returns list of columns at the specified position in fields list, or null if index is negative or greater than fields list size.

Parameters:

index - index of column list to return

Returns:

list of columns at the specified position in fields list or null if index is negative or greater than fields list size

getTableSchemaColumns

public List<org.apache.hadoop.hive.metastore.api.FieldSchema> getTableSchemaColumns()

Safely retrieves Hive table columns from cache.

Returns:

list of table columns defined in hive

getFields

public List<List<org.apache.hadoop.hive.metastore.api.FieldSchema>> getFields()