org.apache.cassandra.db

Class VirtualTableReadQuery

java.lang.Object

org.apache.cassandra.db.monitoring.MonitorableImpl

org.apache.cassandra.db.VirtualTableReadQuery

All Implemented Interfaces:

Monitorable, ReadQuery

Direct Known Subclasses:

VirtualTablePartitionRangeReadQuery, VirtualTableSinglePartitionReadQuery

public abstract class VirtualTableReadQuery
extends MonitorableImpl

Base class for the ReadQuery implementations use to query virtual tables.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	VirtualTableReadQuery(TableMetadata metadata, int nowInSec, ColumnFilter columnFilter, RowFilter rowFilter, DataLimits limits)

Method Summary

Modifier and Type	Method and Description
protected abstract void	appendCQLWhereClause(java.lang.StringBuilder sb)
ColumnFilter	columnFilter() A filter on which (non-PK) columns must be returned by the query.
PartitionIterator	execute(ConsistencyLevel consistency, ClientState clientState, long queryStartNanoTime) Executes the query at the provided consistency level.
PartitionIterator	executeInternal(ReadExecutionController controller) Execute the query for internal queries (that is, it basically executes the query locally).
UnfilteredPartitionIterator	executeLocally(ReadExecutionController executionController) Execute the query locally.
ReadExecutionController	executionController() Starts a new read operation.
DataLimits	limits() The limits for the query.
TableMetadata	metadata() The metadata for the table this is a query on.
java.lang.String	name()
int	nowInSec() The time in seconds to use as "now" for this query.
protected abstract UnfilteredPartitionIterator	queryVirtualTable()
RowFilter	rowFilter() Filters/Resrictions on CQL rows.
java.lang.String	toCQLString() Recreate the CQL string corresponding to this query.

Methods inherited from class org.apache.cassandra.db.monitoring.MonitorableImpl

abort, complete, creationTimeNanos, isAborted, isCompleted, isCrossNode, isInProgress, isSlow, setMonitoringTime, slowTimeoutNanos, timeoutNanos

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.cassandra.db.ReadQuery

empty, getPager, isEmpty, maybeValidateIndex, selectsClustering, selectsFullPartition, selectsKey

Constructor Detail

VirtualTableReadQuery

protected VirtualTableReadQuery(TableMetadata metadata,
                                int nowInSec,
                                ColumnFilter columnFilter,
                                RowFilter rowFilter,
                                DataLimits limits)

Method Detail

executionController

public ReadExecutionController executionController()

Description copied from interface: ReadQuery

Starts a new read operation.

This must be called before executeInternal and passed to it to protect the read. The returned object must be closed on all path and it is thus strongly advised to use it in a try-with-ressource construction.

Returns:

a newly started execution controller for this ReadQuery.

execute

public PartitionIterator execute(ConsistencyLevel consistency,
                                 ClientState clientState,
                                 long queryStartNanoTime)
                          throws RequestExecutionException

Description copied from interface: ReadQuery

Executes the query at the provided consistency level.

Parameters:

consistency - the consistency level to achieve for the query.

clientState - the ClientState for the query. In practice, this can be null unless consistency is a serial consistency.

Returns:

the result of the query.

Throws:

RequestExecutionException

executeLocally

public UnfilteredPartitionIterator executeLocally(ReadExecutionController executionController)

Description copied from interface: ReadQuery

Execute the query locally. This is similar to ReadQuery.executeInternal(ReadExecutionController) but it returns an unfiltered partition iterator that can be merged later on.

Parameters:

executionController - the ReadExecutionController protecting the read.

Returns:

the result of the read query.

queryVirtualTable

protected abstract UnfilteredPartitionIterator queryVirtualTable()

metadata

public TableMetadata metadata()

Description copied from interface: ReadQuery

The metadata for the table this is a query on.

Specified by:

metadata in interface ReadQuery

Returns:

the metadata for the table this is a query on.

name

public java.lang.String name()

Specified by:

name in interface Monitorable

executeInternal

public PartitionIterator executeInternal(ReadExecutionController controller)

Description copied from interface: ReadQuery

Execute the query for internal queries (that is, it basically executes the query locally).

Specified by:

executeInternal in interface ReadQuery

Parameters:

controller - the ReadExecutionController protecting the read.

Returns:

the result of the query.

limits

public DataLimits limits()

Description copied from interface: ReadQuery

The limits for the query.

Specified by:

limits in interface ReadQuery

Returns:

The limits for the query.

nowInSec

public int nowInSec()

Description copied from interface: ReadQuery

The time in seconds to use as "now" for this query.

We use the same time as "now" for the whole query to avoid considering different values as expired during the query, which would be buggy (would throw of counting amongst other things).

Specified by:

nowInSec in interface ReadQuery

Returns:

the time (in seconds) to use as "now".

rowFilter

public RowFilter rowFilter()

Description copied from interface: ReadQuery

Filters/Resrictions on CQL rows.

This contains the restrictions that are not directly handled by the ClusteringIndexFilter. More specifically, this includes any non-PK column restrictions and can include some PK columns restrictions when those can't be satisfied entirely by the clustering index filter (because not all clustering columns have been restricted for instance). If there is 2ndary indexes on the table, one of this restriction might be handled by a 2ndary index.

Specified by:

rowFilter in interface ReadQuery

Returns:

the filter holding the expression that rows must satisfy.

columnFilter

public ColumnFilter columnFilter()

Description copied from interface: ReadQuery

A filter on which (non-PK) columns must be returned by the query.

Specified by:

columnFilter in interface ReadQuery

Returns:

which columns must be fetched by this query.

toCQLString

public java.lang.String toCQLString()

Recreate the CQL string corresponding to this query.

Note that in general the returned string will not be exactly the original user string, first because there isn't always a single syntax for a given query, but also because we don't have all the information needed (we know the non-PK columns queried but not the PK ones as internally we query them all). So this shouldn't be relied too strongly, but this should be good enough for debugging purpose which is what this is for.

appendCQLWhereClause

protected abstract void appendCQLWhereClause(java.lang.StringBuilder sb)