org.apache.drill.exec.planner.common

Class DrillStatsTable

java.lang.Object

org.apache.drill.exec.planner.common.DrillStatsTable

public class DrillStatsTable
extends Object

Wraps the stats table info including schema and tableName. Also materializes stats from storage and keeps them in memory.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DrillStatsTable.ColumnStatistics
static class	DrillStatsTable.ColumnStatistics_v1
static class	DrillStatsTable.DirectoryStatistics
static class	DrillStatsTable.DirectoryStatistics_v0
static class	DrillStatsTable.DirectoryStatistics_v1
static class	DrillStatsTable.Statistics_v0
static class	DrillStatsTable.Statistics_v1 Struct which contains the statistics for the entire directory structure
static class	DrillStatsTable.STATS_VERSION
static class	DrillStatsTable.TableStatistics

Field Summary

Fields

Modifier and Type	Field and Description
static DrillStatsTable.STATS_VERSION	CURRENT_VERSION
static int	NUM_HISTOGRAM_BUCKETS

Constructor Summary

Constructors

Constructor and Description
DrillStatsTable(DrillStatsTable.TableStatistics statistics)
DrillStatsTable(DrillTable table, String schemaName, String tableName, org.apache.hadoop.fs.Path tablePath, org.apache.hadoop.fs.FileSystem fs)

Method Summary

Modifier and Type	Method and Description
static PhysicalPlan	direct(QueryContext context, boolean outcome, String message, Object... values)
static DrillStatsTable.TableStatistics	generateDirectoryStructure(String dirComputedTime, List<DrillStatsTable.ColumnStatistics> columnStatisticsList)
Set<SchemaPath>	getColumns()
static List<StatisticsHolder<?>>	getEstimatedColumnStats(DrillStatsTable statsProvider, SchemaPath fieldName) Returns list of StatisticsKind and statistics values obtained from specified DrillStatsTable for specified column.
static List<StatisticsHolder<?>>	getEstimatedTableStats(DrillStatsTable statsProvider) Returns list of StatisticsKind and statistics values obtained from specified DrillStatsTable.
Histogram	getHistogram(SchemaPath column) Get the histogram of a given column.
static com.fasterxml.jackson.databind.ObjectMapper	getMapper() This method returns the statistics (de)serializer which can be used to (de)/serialize the DrillStatsTable.TableStatistics from/to JSON
Double	getNdv(SchemaPath col) Get the approximate number of distinct values of given column.
Double	getNNRowCount(SchemaPath col) Get non-null rowcount for the column If stats are not present for the given column, a null is returned.
Double	getRowCount() Get row count of the table.
String	getSchemaName()
String	getTableName()
boolean	isMaterialized()
void	materialize() Read the stats from storage and keep them in memory.
static PhysicalPlan	notRequired(QueryContext context, String tbl)
static PhysicalPlan	notSupported(QueryContext context, String tbl)

Methods inherited from class java.lang.Object

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

Field Detail

CURRENT_VERSION

public static final DrillStatsTable.STATS_VERSION CURRENT_VERSION

NUM_HISTOGRAM_BUCKETS

public static final int NUM_HISTOGRAM_BUCKETS

See Also:

Constant Field Values

Constructor Detail

DrillStatsTable

public DrillStatsTable(DrillTable table,
                       String schemaName,
                       String tableName,
                       org.apache.hadoop.fs.Path tablePath,
                       org.apache.hadoop.fs.FileSystem fs)

DrillStatsTable

public DrillStatsTable(DrillStatsTable.TableStatistics statistics)

Method Detail

getSchemaName

public String getSchemaName()

getTableName

public String getTableName()

isMaterialized

public boolean isMaterialized()

getNdv

public Double getNdv(SchemaPath col)

Get the approximate number of distinct values of given column. If stats are not present for the given column, a null is returned. Note: returned data may not be accurate. Accuracy depends on whether the table data has changed after the stats are computed.

Parameters:

col - - column for which approximate count distinct is desired

Returns:

approximate count distinct of the column, if available. NULL otherwise.

getColumns

public Set<SchemaPath> getColumns()

getRowCount

public Double getRowCount()

Get row count of the table. Returns null if stats are not present. Note: returned data may not be accurate. Accuracy depends on whether the table data has changed after the stats are computed.

Returns:

rowcount for the table, if available. NULL otherwise.

getNNRowCount

public Double getNNRowCount(SchemaPath col)

Get non-null rowcount for the column If stats are not present for the given column, a null is returned. Note: returned data may not be accurate. Accuracy depends on whether the table data has changed after the stats are computed.

Parameters:

col - - column for which non-null rowcount is desired

Returns:

non-null rowcount of the column, if available. NULL otherwise.

getHistogram

public Histogram getHistogram(SchemaPath column)

Get the histogram of a given column. If stats are not present for the given column, a null is returned.

Note: returned data may not be accurate. Accuracy depends on whether the table data has changed after the stats are computed.

Parameters:

column - path to the column whose histogram should be obtained

Returns:

Histogram for this column

materialize

public void materialize()

Read the stats from storage and keep them in memory.

generateDirectoryStructure

public static DrillStatsTable.TableStatistics generateDirectoryStructure(String dirComputedTime,
                                                                         List<DrillStatsTable.ColumnStatistics> columnStatisticsList)

direct

public static PhysicalPlan direct(QueryContext context,
                                  boolean outcome,
                                  String message,
                                  Object... values)

notSupported

public static PhysicalPlan notSupported(QueryContext context,
                                        String tbl)

notRequired

public static PhysicalPlan notRequired(QueryContext context,
                                       String tbl)

getMapper

public static com.fasterxml.jackson.databind.ObjectMapper getMapper()

This method returns the statistics (de)serializer which can be used to (de)/serialize the DrillStatsTable.TableStatistics from/to JSON

getEstimatedTableStats

public static List<StatisticsHolder<?>> getEstimatedTableStats(DrillStatsTable statsProvider)

Returns list of StatisticsKind and statistics values obtained from specified DrillStatsTable.

Parameters:

statsProvider - the source of statistics

Returns:

list of StatisticsKind and statistics values

getEstimatedColumnStats

public static List<StatisticsHolder<?>> getEstimatedColumnStats(DrillStatsTable statsProvider,
                                                                SchemaPath fieldName)

Returns list of StatisticsKind and statistics values obtained from specified DrillStatsTable for specified column.

Parameters:

statsProvider - the source of statistics

fieldName - name of the columns whose statistics should be obtained

Returns:

list of StatisticsKind and statistics values