Package org.apache.drill.exec.store.sys

Class SystemTableScan

java.lang.Object

org.apache.drill.exec.physical.base.AbstractBase

org.apache.drill.exec.physical.base.AbstractGroupScan

org.apache.drill.exec.store.sys.SystemTableScan

All Implemented Interfaces:

Iterable<PhysicalOperator>, GraphValue<PhysicalOperator>, FragmentLeaf, GroupScan, HasAffinity, Leaf, PhysicalOperator, Scan, SubScan

public class SystemTableScan
extends AbstractGroupScan
implements SubScan

Field Summary

Fields

Modifier and Type	Field	Description
static final String	OPERATOR_TYPE

Fields inherited from class org.apache.drill.exec.physical.base.AbstractBase

INIT_ALLOCATION, initialAllocation, MAX_ALLOCATION, maxAllocation, userName

Fields inherited from interface org.apache.drill.exec.physical.base.GroupScan

ALL_COLUMNS

Constructor Summary

Constructors

Constructor	Description
SystemTableScan(SystemTable table, int maxRecordsToRead, StoragePluginRegistry engineRegistry)
SystemTableScan(SystemTable table, int maxRecordsToRead, SystemTablePlugin plugin)
SystemTableScan(SystemTable table, SystemTablePlugin plugin)

Method Summary

Modifier and Type	Method	Description
void	applyAssignments(List<CoordinationProtos.DrillbitEndpoint> endpoints)
GroupScan	applyLimit(int maxRecords)	By default, return null to indicate row count based prune is not supported.
GroupScan	clone(List<SchemaPath> columns)	Returns a clone of GroupScan instance, except that the new GroupScan will use the provided list of columns .
GroupScan	clone(SystemTableScan systemTableScan, int maxRecordsToRead)
List<SchemaPath>	getColumns()	Returns a list of columns scanned by this group scan
String	getDigest()	Example: SystemTableScan [table=OPTION, distributed=false, maxRecordsToRead=1]
DistributionAffinity	getDistributionAffinity()	Get distribution affinity which describes the parallelization strategy of the operator.
long	getInitialAllocation()
long	getMaxAllocation()
int	getMaxParallelizationWidth()
int	getMaxRecordsToRead()
int	getMinParallelizationWidth()	At minimum, the GroupScan requires these many fragments to run.
PhysicalOperator	getNewWithChildren(List<PhysicalOperator> children)	Regenerate with this node with a new set of children.
List<EndpointAffinity>	getOperatorAffinity()	If distributed, the scan needs to happen on every node.
String	getOperatorType()
SystemTablePlugin	getPlugin()
ScanStats	getScanStats()	System tables do not need stats.
SubScan	getSpecificScan(int minorFragmentId)
SystemTable	getTable()
boolean	supportsLimitPushdown()	Default is not to support limit pushdown.

Methods inherited from class org.apache.drill.exec.physical.base.AbstractGroupScan

accept, applyFilter, canPushdownProjects, enforceWidth, getAnalyzeInfoProvider, getColumnValueCount, getFiles, getFilter, getMetadataProvider, getPartitionColumns, getScanStats, getScanStats, getSelectionRoot, getTableMetadata, hasFiles, isDistributed, isExecutable, iterator, supportsFilterPushDown, supportsPartitionFilterPushdown, usedMetastore

Methods inherited from class org.apache.drill.exec.physical.base.AbstractBase

accept, getCost, getOperatorId, getSVMode, getUserName, isBufferedOperator, setCost, setMaxAllocation, setOperatorId

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.drill.common.graph.GraphValue

accept

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Methods inherited from interface org.apache.drill.exec.physical.base.PhysicalOperator

accept, getCost, getOperatorId, getSVMode, getUserName, isBufferedOperator, isExecutable, setCost, setMaxAllocation, setOperatorId

Field Details

OPERATOR_TYPE

public static final String OPERATOR_TYPE

See Also:

• Constant Field Values

Constructor Details

SystemTableScan

public SystemTableScan(SystemTable table,
 int maxRecordsToRead,
 StoragePluginRegistry engineRegistry)
                throws ExecutionSetupException

Throws:

ExecutionSetupException

SystemTableScan

public SystemTableScan(SystemTable table,
 SystemTablePlugin plugin)

SystemTableScan

public SystemTableScan(SystemTable table,
 int maxRecordsToRead,
 SystemTablePlugin plugin)

Method Details

getScanStats

public ScanStats getScanStats()

System tables do not need stats.

Overrides:

getScanStats in class AbstractGroupScan

Returns:

a trivial stats table

getNewWithChildren

public PhysicalOperator getNewWithChildren(List<PhysicalOperator> children)

Description copied from interface: PhysicalOperator

Regenerate with this node with a new set of children. This is used in the case of materialization or optimization.

Specified by:

getNewWithChildren in interface PhysicalOperator

Parameters:

children -

applyAssignments

public void applyAssignments(List<CoordinationProtos.DrillbitEndpoint> endpoints)

Specified by:

applyAssignments in interface GroupScan

getColumns

public List<SchemaPath> getColumns()

Description copied from interface: GroupScan

Returns a list of columns scanned by this group scan

Specified by:

getColumns in interface GroupScan

Overrides:

getColumns in class AbstractGroupScan

getSpecificScan

public SubScan getSpecificScan(int minorFragmentId)

Specified by:

getSpecificScan in interface GroupScan

getMaxParallelizationWidth

public int getMaxParallelizationWidth()

Specified by:

getMaxParallelizationWidth in interface GroupScan

getMinParallelizationWidth

public int getMinParallelizationWidth()

Description copied from interface: GroupScan

At minimum, the GroupScan requires these many fragments to run. Currently, this is used in SimpleParallelizer

Specified by:

getMinParallelizationWidth in interface GroupScan

Overrides:

getMinParallelizationWidth in class AbstractGroupScan

Returns:

the minimum number of fragments that should run

getInitialAllocation

public long getInitialAllocation()

Specified by:

getInitialAllocation in interface PhysicalOperator

Overrides:

getInitialAllocation in class AbstractGroupScan

Returns:

The memory to preallocate for this operator

getMaxAllocation

public long getMaxAllocation()

Specified by:

getMaxAllocation in interface PhysicalOperator

Overrides:

getMaxAllocation in class AbstractGroupScan

Returns:

The maximum memory this operator can allocate

getDigest

public String getDigest()

Example: SystemTableScan [table=OPTION, distributed=false, maxRecordsToRead=1]

Specified by:

getDigest in interface GroupScan

Returns:

string representation of system table scan

getOperatorType

public String getOperatorType()

Specified by:

getOperatorType in interface PhysicalOperator

Overrides:

getOperatorType in class AbstractGroupScan

getOperatorAffinity

public List<EndpointAffinity> getOperatorAffinity()

If distributed, the scan needs to happen on every node. Since width is enforced, the number of fragments equals number of Drillbits. And here we set, each endpoint as mandatory assignment required to ensure every Drillbit executes a fragment.

Specified by:

getOperatorAffinity in interface HasAffinity

Overrides:

getOperatorAffinity in class AbstractGroupScan

Returns:

the Drillbit endpoint affinities

getDistributionAffinity

public DistributionAffinity getDistributionAffinity()

Description copied from interface: HasAffinity

Get distribution affinity which describes the parallelization strategy of the operator.

Specified by:

getDistributionAffinity in interface HasAffinity

Overrides:

getDistributionAffinity in class AbstractGroupScan

clone

public GroupScan clone(List<SchemaPath> columns)

Description copied from interface: GroupScan

Returns a clone of GroupScan instance, except that the new GroupScan will use the provided list of columns .

Specified by:

clone in interface GroupScan

Overrides:

clone in class AbstractGroupScan

clone

public GroupScan clone(SystemTableScan systemTableScan,
 int maxRecordsToRead)

supportsLimitPushdown

public boolean supportsLimitPushdown()

Description copied from class: AbstractGroupScan

Default is not to support limit pushdown.

Specified by:

supportsLimitPushdown in interface GroupScan

Overrides:

supportsLimitPushdown in class AbstractGroupScan

applyLimit

public GroupScan applyLimit(int maxRecords)

Description copied from class: AbstractGroupScan

By default, return null to indicate row count based prune is not supported. Each group scan subclass should override, if it supports row count based prune.

Specified by:

applyLimit in interface GroupScan

Overrides:

applyLimit in class AbstractGroupScan

Parameters:

maxRecords - : the number of rows requested from group scan.

Returns:

a new instance of group scan if the prune is successful. null when either if row-based prune is not supported, or if prune is not successful.

getTable

public SystemTable getTable()

getMaxRecordsToRead

public int getMaxRecordsToRead()

getPlugin

public SystemTablePlugin getPlugin()