Package org.apache.drill.exec.physical.base

Class ScanStats

java.lang.Object

org.apache.drill.exec.physical.base.ScanStats

public class ScanStats
extends Object

Cost estimate for a scan. In general, relative costs are more important than absolute costs. If a scan supports filter push-down, the cost of the scan after the push-down must be less than the combined cost of the scan + project before push down, else Calcite will ignore the push-down. Also, the estimated row count may influence whether the table can be broadcast or hash partitioned. Otherwise, Calcite has no real choices based on scan cost.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	ScanStats.GroupScanProperty

Field Summary

Fields

Modifier and Type	Field	Description
static final ScanStats	TRIVIAL_TABLE
static final ScanStats	ZERO_RECORD_TABLE

Constructor Summary

Constructors

Constructor	Description
ScanStats(ScanStats.GroupScanProperty groupScanProperty, double recordCount, double cpuCost, double diskCost)

Method Summary

Modifier and Type	Method	Description
double	getCpuCost()
double	getDiskCost()
ScanStats.GroupScanProperty	getGroupScanProperty()	Return whether GroupScan knows the exact row count in the result of getSize() call.
double	getRecordCount()
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

TRIVIAL_TABLE

public static final ScanStats TRIVIAL_TABLE

ZERO_RECORD_TABLE

public static final ScanStats ZERO_RECORD_TABLE

Constructor Details

ScanStats

public ScanStats(ScanStats.GroupScanProperty groupScanProperty,
 double recordCount,
 double cpuCost,
 double diskCost)

Method Details

getGroupScanProperty

public ScanStats.GroupScanProperty getGroupScanProperty()

Return whether GroupScan knows the exact row count in the result of getSize() call. By default, group scan does not know the exact row count, before it scans every rows. Currently, Parquet group scan will return the exact row count.

Returns:

group scan property

getRecordCount

public double getRecordCount()

getCpuCost

public double getCpuCost()

getDiskCost

public double getDiskCost()

toString

public String toString()

Overrides:

toString in class Object