org.apache.cassandra.db

Class SinglePartitionReadCommand

java.lang.Object

org.apache.cassandra.db.ReadCommand

org.apache.cassandra.db.SinglePartitionReadCommand

All Implemented Interfaces:

ReadQuery

public class SinglePartitionReadCommand
extends ReadCommand

A read command that selects a (part of a) single partition.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SinglePartitionReadCommand.Group Groups multiple single partition read commands.

Nested classes/interfaces inherited from class org.apache.cassandra.db.ReadCommand

ReadCommand.Kind, ReadCommand.SelectionDeserializer

Field Summary

Fields

Modifier and Type	Field and Description
protected static ReadCommand.SelectionDeserializer	selectionDeserializer

Fields inherited from class org.apache.cassandra.db.ReadCommand

index, legacyPagedRangeCommandSerializer, legacyRangeSliceCommandSerializer, legacyReadCommandSerializer, logger, rangeSliceSerializer, serializer

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

EMPTY

Constructor Summary

Constructors

Constructor and Description
SinglePartitionReadCommand(boolean isDigest, int digestVersion, boolean isForThrift, CFMetaData metadata, int nowInSec, ColumnFilter columnFilter, RowFilter rowFilter, DataLimits limits, DecoratedKey partitionKey, ClusteringIndexFilter clusteringIndexFilter)

Method Summary

Modifier and Type	Method and Description
protected void	appendCQLWhereClause(java.lang.StringBuilder sb)
ClusteringIndexFilter	clusteringIndexFilter()
ClusteringIndexFilter	clusteringIndexFilter(DecoratedKey key) The clustering index filter this command to use for the provided key.
SinglePartitionReadCommand	copy() Returns a copy of this command.
static SinglePartitionReadCommand	create(boolean isForThrift, CFMetaData metadata, int nowInSec, ColumnFilter columnFilter, RowFilter rowFilter, DataLimits limits, DecoratedKey partitionKey, ClusteringIndexFilter clusteringIndexFilter) Creates a new read command on a single partition for thrift.
static SinglePartitionReadCommand	create(CFMetaData metadata, int nowInSec, java.nio.ByteBuffer key, Slices slices) Creates a new single partition slice command for the provided slices.
static SinglePartitionReadCommand	create(CFMetaData metadata, int nowInSec, ColumnFilter columnFilter, RowFilter rowFilter, DataLimits limits, DecoratedKey partitionKey, ClusteringIndexFilter clusteringIndexFilter) Creates a new read command on a single partition.
static SinglePartitionReadCommand	create(CFMetaData metadata, int nowInSec, DecoratedKey key, ColumnFilter columnFilter, ClusteringIndexFilter filter) Creates a new read command on a single partition.
static SinglePartitionReadCommand	create(CFMetaData metadata, int nowInSec, DecoratedKey key, Slice slice) Creates a new single partition slice command for the provided single slice.
static SinglePartitionReadCommand	create(CFMetaData metadata, int nowInSec, DecoratedKey key, Slices slices) Creates a new single partition slice command for the provided slices.
MessageOut<ReadCommand>	createMessage(int version) Creates a message for this command.
PartitionIterator	execute(ConsistencyLevel consistency, ClientState clientState) Executes the query at the provided consistency level.
SinglePartitionReadCommand	forPaging(Clustering lastReturned, int pageSize) Returns a new command suitable to paging from the last returned row.
static SinglePartitionReadCommand	fullPartitionRead(CFMetaData metadata, int nowInSec, java.nio.ByteBuffer key) Creates a new read command that queries a single partition in its entirety.
static SinglePartitionReadCommand	fullPartitionRead(CFMetaData metadata, int nowInSec, DecoratedKey key) Creates a new read command that queries a single partition in its entirety.
SinglePartitionPager	getPager(PagingState pagingState, int protocolVersion) Returns a pager for the query.
long	getTimeout() The configured timeout for this command.
protected int	oldestUnrepairedTombstone()
DecoratedKey	partitionKey()
UnfilteredRowIterator	queryMemtableAndDisk(ColumnFamilyStore cfs, OpOrder.Group readOp) Queries both memtable and sstables to fetch the result of this query.
protected UnfilteredPartitionIterator	queryStorage(ColumnFamilyStore cfs, ReadOrderGroup orderGroup)
protected void	recordLatency(TableMetrics metric, long latencyNanos)
protected long	selectionSerializedSize(int version)
boolean	selectsClustering(DecoratedKey key, Clustering clustering)
boolean	selectsKey(DecoratedKey key)
protected void	serializeSelection(DataOutputPlus out, int version)
java.lang.String	toString()

Methods inherited from class org.apache.cassandra.db.ReadCommand

columnFilter, createResponse, digestVersion, executeInternal, executeLocally, getIndex, indexSerializedSize, isDigestQuery, isForThrift, limits, metadata, nowInSec, rowFilter, setDigestVersion, setIsDigestQuery, startOrderGroup, toCQLString, withoutPurgeableTombstones

Methods inherited from class java.lang.Object

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

Field Detail

selectionDeserializer

protected static final ReadCommand.SelectionDeserializer selectionDeserializer

Constructor Detail

SinglePartitionReadCommand

public SinglePartitionReadCommand(boolean isDigest,
                                  int digestVersion,
                                  boolean isForThrift,
                                  CFMetaData metadata,
                                  int nowInSec,
                                  ColumnFilter columnFilter,
                                  RowFilter rowFilter,
                                  DataLimits limits,
                                  DecoratedKey partitionKey,
                                  ClusteringIndexFilter clusteringIndexFilter)

Method Detail

create

public static SinglePartitionReadCommand create(CFMetaData metadata,
                                                int nowInSec,
                                                ColumnFilter columnFilter,
                                                RowFilter rowFilter,
                                                DataLimits limits,
                                                DecoratedKey partitionKey,
                                                ClusteringIndexFilter clusteringIndexFilter)

Creates a new read command on a single partition.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

columnFilter - the column filter to use for the query.

rowFilter - the row filter to use for the query.

limits - the limits to use for the query.

partitionKey - the partition key for the partition to query.

clusteringIndexFilter - the clustering index filter to use for the query.

Returns:

a newly created read command.

create

public static SinglePartitionReadCommand create(boolean isForThrift,
                                                CFMetaData metadata,
                                                int nowInSec,
                                                ColumnFilter columnFilter,
                                                RowFilter rowFilter,
                                                DataLimits limits,
                                                DecoratedKey partitionKey,
                                                ClusteringIndexFilter clusteringIndexFilter)

Creates a new read command on a single partition for thrift.

Parameters:

isForThrift - whether the query is for thrift or not.

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

columnFilter - the column filter to use for the query.

rowFilter - the row filter to use for the query.

limits - the limits to use for the query.

partitionKey - the partition key for the partition to query.

clusteringIndexFilter - the clustering index filter to use for the query.

Returns:

a newly created read command.

create

public static SinglePartitionReadCommand create(CFMetaData metadata,
                                                int nowInSec,
                                                DecoratedKey key,
                                                ColumnFilter columnFilter,
                                                ClusteringIndexFilter filter)

Creates a new read command on a single partition.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

columnFilter - the column filter to use for the query.

filter - the clustering index filter to use for the query.

Returns:

a newly created read command. The returned command will use no row filter and have no limits.

fullPartitionRead

public static SinglePartitionReadCommand fullPartitionRead(CFMetaData metadata,
                                                           int nowInSec,
                                                           DecoratedKey key)

Creates a new read command that queries a single partition in its entirety.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

Returns:

a newly created read command that queries all the rows of key.

fullPartitionRead

public static SinglePartitionReadCommand fullPartitionRead(CFMetaData metadata,
                                                           int nowInSec,
                                                           java.nio.ByteBuffer key)

Creates a new read command that queries a single partition in its entirety.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

Returns:

a newly created read command that queries all the rows of key.

create

public static SinglePartitionReadCommand create(CFMetaData metadata,
                                                int nowInSec,
                                                DecoratedKey key,
                                                Slice slice)

Creates a new single partition slice command for the provided single slice.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

slice - the slice of rows to query.

Returns:

a newly created read command that queries slice in key. The returned query will query every columns for the table (without limit or row filtering) and be in forward order.

create

public static SinglePartitionReadCommand create(CFMetaData metadata,
                                                int nowInSec,
                                                DecoratedKey key,
                                                Slices slices)

Creates a new single partition slice command for the provided slices.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

slices - the slices of rows to query.

Returns:

a newly created read command that queries the slices in key. The returned query will query every columns for the table (without limit or row filtering) and be in forward order.

create

public static SinglePartitionReadCommand create(CFMetaData metadata,
                                                int nowInSec,
                                                java.nio.ByteBuffer key,
                                                Slices slices)

Creates a new single partition slice command for the provided slices.

Parameters:

metadata - the table to query.

nowInSec - the time in seconds to use are "now" for this query.

key - the partition key for the partition to query.

slices - the slices of rows to query.

Returns:

a newly created read command that queries the slices in key. The returned query will query every columns for the table (without limit or row filtering) and be in forward order.

copy

public SinglePartitionReadCommand copy()

Description copied from class: ReadCommand

Returns a copy of this command.

Specified by:

copy in class ReadCommand

Returns:

a copy of this command.

partitionKey

public DecoratedKey partitionKey()

clusteringIndexFilter

public ClusteringIndexFilter clusteringIndexFilter()

clusteringIndexFilter

public ClusteringIndexFilter clusteringIndexFilter(DecoratedKey key)

Description copied from class: ReadCommand

The clustering index filter this command to use for the provided key.

Note that that method should only be called on a key actually queried by this command and in practice, this will almost always return the same filter, but for the sake of paging, the filter on the first key of a range command might be slightly different.

Specified by:

clusteringIndexFilter in class ReadCommand

Parameters:

key - a partition key queried by this command.

Returns:

the ClusteringIndexFilter to use for the partition of key key.

getTimeout

public long getTimeout()

Description copied from class: ReadCommand

The configured timeout for this command.

Specified by:

getTimeout in class ReadCommand

Returns:

the configured timeout for this command.

selectsKey

public boolean selectsKey(DecoratedKey key)

Returns:

true if the read query would select the given key, including checks against the row filter, if checkRowFilter is true

selectsClustering

public boolean selectsClustering(DecoratedKey key,
                                 Clustering clustering)

Returns:

true if the read query would select the given clustering, including checks against the row filter, if checkRowFilter is true

forPaging

public SinglePartitionReadCommand forPaging(Clustering lastReturned,
                                            int pageSize)

Returns a new command suitable to paging from the last returned row.

Parameters:

lastReturned - the last row returned by the previous page. The newly created command will only query row that comes after this (in query order). This can be null if this is the first page.

pageSize - the size to use for the page to query.

Returns:

the newly create command.

execute

public PartitionIterator execute(ConsistencyLevel consistency,
                                 ClientState clientState)
                          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

getPager

public SinglePartitionPager getPager(PagingState pagingState,
                                     int protocolVersion)

Description copied from interface: ReadQuery

Returns a pager for the query.

Parameters:

pagingState - the PagingState to start from if this is a paging continuation. This can be null if this is the start of paging.

protocolVersion - the protocol version to use for the paging state of that pager.

Returns:

a pager for the query.

recordLatency

protected void recordLatency(TableMetrics metric,
                             long latencyNanos)

Specified by:

recordLatency in class ReadCommand

queryStorage

protected UnfilteredPartitionIterator queryStorage(ColumnFamilyStore cfs,
                                                   ReadOrderGroup orderGroup)

Specified by:

queryStorage in class ReadCommand

queryMemtableAndDisk

public UnfilteredRowIterator queryMemtableAndDisk(ColumnFamilyStore cfs,
                                                  OpOrder.Group readOp)

Queries both memtable and sstables to fetch the result of this query.

Please note that this method: 1) does not check the row cache. 2) does not apply the query limit, nor the row filter (and so ignore 2ndary indexes). Those are applied in ReadCommand.executeLocally(org.apache.cassandra.db.ReadOrderGroup). 3) does not record some of the read metrics (latency, scanned cells histograms) nor throws TombstoneOverwhelmingException. It is publicly exposed because there is a few places where that is exactly what we want, but it should be used only where you know you don't need thoses things.

Also note that one must have "started" a OpOrder.Group on the queried table, and that is to enforce that that it is required as parameter, even though it's not explicitlly used by the method.

oldestUnrepairedTombstone

protected int oldestUnrepairedTombstone()

Specified by:

oldestUnrepairedTombstone in class ReadCommand

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

createMessage

public MessageOut<ReadCommand> createMessage(int version)

Description copied from class: ReadCommand

Creates a message for this command.

Specified by:

createMessage in class ReadCommand

appendCQLWhereClause

protected void appendCQLWhereClause(java.lang.StringBuilder sb)

Specified by:

appendCQLWhereClause in class ReadCommand

serializeSelection

protected void serializeSelection(DataOutputPlus out,
                                  int version)
                           throws java.io.IOException

Specified by:

serializeSelection in class ReadCommand

Throws:

java.io.IOException

selectionSerializedSize

protected long selectionSerializedSize(int version)

Specified by:

selectionSerializedSize in class ReadCommand