Package org.apache.cassandra.db.filter

Class DataLimits

java.lang.Object

org.apache.cassandra.db.filter.DataLimits

public abstract class DataLimits
extends java.lang.Object

Object in charge of tracking if we have fetch enough data for a given query. This is more complicated than a single count because we support PER PARTITION limits, but also due to GROUP BY and paging.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	DataLimits.Counter
static class	DataLimits.Kind
static class	DataLimits.Serializer

Field Summary

Fields

Modifier and Type	Field	Description
static DataLimits	DISTINCT_NONE
static int	NO_LIMIT
static DataLimits	NONE
static DataLimits.Serializer	serializer

Constructor Summary

Constructors

Constructor	Description
DataLimits()

Method Summary

Modifier and Type	Method	Description
abstract int	count()	The max number of results this limits enforces.
static DataLimits	cqlLimits(int cqlRowLimit)
static DataLimits	cqlLimits(int cqlRowLimit, int perPartitionLimit)
static DataLimits	distinctLimits(int cqlRowLimit)
abstract float	estimateTotalResults(ColumnFamilyStore cfs)	Estimate the number of results that a full scan of the provided cfs would yield.
PartitionIterator	filter(PartitionIterator iter, int nowInSec, boolean countPartitionsWithOnlyStaticData, boolean enforceStrictLiveness)
UnfilteredPartitionIterator	filter(UnfilteredPartitionIterator iter, int nowInSec, boolean countPartitionsWithOnlyStaticData)
UnfilteredRowIterator	filter(UnfilteredRowIterator iter, int nowInSec, boolean countPartitionsWithOnlyStaticData)
DataLimits	forGroupByInternalPaging(GroupingState state)	Creates a DataLimits instance to be used for paginating internally GROUP BY queries.
abstract DataLimits	forPaging(int pageSize)
abstract DataLimits	forPaging(int pageSize, java.nio.ByteBuffer lastReturnedKey, int lastReturnedKeyRemaining)
abstract DataLimits	forShortReadRetry(int toFetch)
static DataLimits	groupByLimits(int groupLimit, int groupPerPartitionLimit, int rowLimit, AggregationSpecification groupBySpec)
abstract boolean	hasEnoughLiveData(CachedPartition cached, int nowInSec, boolean countPartitionsWithOnlyStaticData, boolean enforceStrictLiveness)
abstract boolean	isDistinct()
boolean	isExhausted(DataLimits.Counter counter)
boolean	isGroupByLimit()
abstract boolean	isUnlimited()
abstract DataLimits.Kind	kind()
abstract DataLimits.Counter	newCounter(int nowInSec, boolean assumeLiveData, boolean countPartitionsWithOnlyStaticData, boolean enforceStrictLiveness)	Returns a new Counter for this limits.
abstract int	perPartitionCount()
abstract DataLimits	withoutState()	Returns equivalent limits but where any internal state kept to track where we are of paging and/or grouping is discarded.

Methods inherited from class java.lang.Object

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

Field Detail

serializer

public static final DataLimits.Serializer serializer

NO_LIMIT

public static final int NO_LIMIT

See Also:

Constant Field Values

NONE

public static final DataLimits NONE

DISTINCT_NONE

public static final DataLimits DISTINCT_NONE

Constructor Detail

DataLimits

public DataLimits()

Method Detail

cqlLimits

public static DataLimits cqlLimits(int cqlRowLimit)

cqlLimits

public static DataLimits cqlLimits(int cqlRowLimit,
                                   int perPartitionLimit)

groupByLimits

public static DataLimits groupByLimits(int groupLimit,
                                       int groupPerPartitionLimit,
                                       int rowLimit,
                                       AggregationSpecification groupBySpec)

distinctLimits

public static DataLimits distinctLimits(int cqlRowLimit)

kind

public abstract DataLimits.Kind kind()

isUnlimited

public abstract boolean isUnlimited()

isDistinct

public abstract boolean isDistinct()

isGroupByLimit

public boolean isGroupByLimit()

isExhausted

public boolean isExhausted(DataLimits.Counter counter)

forPaging

public abstract DataLimits forPaging(int pageSize)

forPaging

public abstract DataLimits forPaging(int pageSize,
                                     java.nio.ByteBuffer lastReturnedKey,
                                     int lastReturnedKeyRemaining)

forShortReadRetry

public abstract DataLimits forShortReadRetry(int toFetch)

forGroupByInternalPaging

public DataLimits forGroupByInternalPaging(GroupingState state)

Creates a DataLimits instance to be used for paginating internally GROUP BY queries.

Parameters:

state - the GroupMaker state

Returns:

a DataLimits instance to be used for paginating internally GROUP BY queries

hasEnoughLiveData

public abstract boolean hasEnoughLiveData(CachedPartition cached,
                                          int nowInSec,
                                          boolean countPartitionsWithOnlyStaticData,
                                          boolean enforceStrictLiveness)

newCounter

public abstract DataLimits.Counter newCounter(int nowInSec,
                                              boolean assumeLiveData,
                                              boolean countPartitionsWithOnlyStaticData,
                                              boolean enforceStrictLiveness)

Returns a new Counter for this limits.

Parameters:

nowInSec - the current time in second (to decide what is expired or not).

assumeLiveData - if true, the counter will assume that every row passed is live and won't thus check for liveness, otherwise it will. This should be true when used on a RowIterator (since it only returns live rows), false otherwise.

countPartitionsWithOnlyStaticData - if true the partitions with only static data should be counted as 1 valid row.

enforceStrictLiveness - whether the row should be purged if there is no PK liveness info, normally retrieved from TableMetadata.enforceStrictLiveness()

Returns:

a new Counter for this limits.

count

public abstract int count()

The max number of results this limits enforces.

Note that the actual definition of "results" depends a bit: for "normal" queries it's a number of rows, but for GROUP BY queries it's a number of groups.

Returns:

the maximum number of results this limits enforces.

perPartitionCount

public abstract int perPartitionCount()

withoutState

public abstract DataLimits withoutState()

Returns equivalent limits but where any internal state kept to track where we are of paging and/or grouping is discarded.

filter

public UnfilteredPartitionIterator filter(UnfilteredPartitionIterator iter,
                                          int nowInSec,
                                          boolean countPartitionsWithOnlyStaticData)

filter

public UnfilteredRowIterator filter(UnfilteredRowIterator iter,
                                    int nowInSec,
                                    boolean countPartitionsWithOnlyStaticData)

filter

public PartitionIterator filter(PartitionIterator iter,
                                int nowInSec,
                                boolean countPartitionsWithOnlyStaticData,
                                boolean enforceStrictLiveness)

estimateTotalResults

public abstract float estimateTotalResults(ColumnFamilyStore cfs)

Estimate the number of results that a full scan of the provided cfs would yield.