org.apache.hadoop.hbase.client

Class Query

java.lang.Object

org.apache.hadoop.hbase.client.Operation

org.apache.hadoop.hbase.client.OperationWithAttributes

org.apache.hadoop.hbase.client.Query

All Implemented Interfaces:

Attributes

Direct Known Subclasses:

Get, Scan

@InterfaceAudience.Public
public abstract class Query
extends OperationWithAttributes

Base class for HBase read operations; e.g. Scan and Get.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<byte[],TimeRange>	colFamTimeRangeMap
protected Consistency	consistency
protected Filter	filter
protected Boolean	loadColumnFamiliesOnDemand
protected boolean	queryMetricsEnabled
protected int	targetReplicaId

Fields inherited from class org.apache.hadoop.hbase.client.OperationWithAttributes

ID_ATRIBUTE

Constructor Summary

Constructors

Constructor and Description
Query()

Method Summary

Modifier and Type	Method and Description
boolean	doLoadColumnFamiliesOnDemand() Get the logical value indicating whether on-demand CF loading should be allowed.
byte[]	getACL() Returns The serialized ACL for this operation, or null if none
Authorizations	getAuthorizations() Returns The authorizations this Query is associated with.
Map<byte[],TimeRange>	getColumnFamilyTimeRange() Returns A map of column families to time ranges
Consistency	getConsistency() Returns the consistency level for this operation
Filter	getFilter()
IsolationLevel	getIsolationLevel() Returns The isolation level of this query.
Boolean	getLoadColumnFamiliesOnDemandValue() Get the raw loadColumnFamiliesOnDemand setting; if it's not set, can be null.
int	getReplicaId() Returns region replica id where Query will fetch data from.
boolean	isQueryMetricsEnabled() Returns whether query metrics are enabled
Query	setACL(Map<String,Permission> perms) Set the ACL for the operation.
Query	setACL(String user, Permission perms) Set the ACL for the operation.
Query	setAuthorizations(Authorizations authorizations) Sets the authorizations to be used by this Query
Query	setColumnFamilyTimeRange(byte[] cf, long minStamp, long maxStamp) Get versions of columns only within the specified timestamp range, [minStamp, maxStamp) on a per CF bases.
Query	setConsistency(Consistency consistency) Sets the consistency level for this operation
Query	setFilter(Filter filter) Apply the specified server-side filter when performing the Query.
Query	setIsolationLevel(IsolationLevel level) Set the isolation level for this query.
Query	setLoadColumnFamiliesOnDemand(boolean value) Set the value indicating whether loading CFs on demand should be allowed (cluster default is false).
Query	setQueryMetricsEnabled(boolean enabled) Enables the return of QueryMetrics alongside the corresponding result(s) for this query
Query	setReplicaId(int Id) Specify region replica id where Query will fetch data from.

Methods inherited from class org.apache.hadoop.hbase.client.OperationWithAttributes

getAttribute, getAttributeSize, getAttributesMap, getId, getPriority, setAttribute, setId, setPriority

Methods inherited from class org.apache.hadoop.hbase.client.Operation

getFingerprint, toJSON, toJSON, toMap, toMap, toString, toString

Methods inherited from class java.lang.Object

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

Field Detail

filter

protected Filter filter

targetReplicaId

protected int targetReplicaId

consistency

protected Consistency consistency

colFamTimeRangeMap

protected Map<byte[],TimeRange> colFamTimeRangeMap

loadColumnFamiliesOnDemand

protected Boolean loadColumnFamiliesOnDemand

queryMetricsEnabled

protected boolean queryMetricsEnabled

Constructor Detail

Query

public Query()

Method Detail

getFilter

public Filter getFilter()

setFilter

public Query setFilter(Filter filter)

Apply the specified server-side filter when performing the Query. Only Filter.filterCell(org.apache.hadoop.hbase.Cell) is called AFTER all tests for ttl, column match, deletes and column family's max versions have been run.

Parameters:

filter - filter to run on the server

Returns:

this for invocation chaining

setAuthorizations

public Query setAuthorizations(Authorizations authorizations)

Sets the authorizations to be used by this Query

getAuthorizations

public Authorizations getAuthorizations()
                                 throws DeserializationException

Returns The authorizations this Query is associated with. n

Throws:

DeserializationException

getACL

public byte[] getACL()

Returns The serialized ACL for this operation, or null if none

setACL

public Query setACL(String user,
                    Permission perms)

Set the ACL for the operation.

Parameters:

user - User short name

perms - Permissions for the user

setACL

public Query setACL(Map<String,Permission> perms)

Set the ACL for the operation.

Parameters:

perms - A map of permissions for a user or users

getConsistency

public Consistency getConsistency()

Returns the consistency level for this operation

Returns:

the consistency level

setConsistency

public Query setConsistency(Consistency consistency)

Sets the consistency level for this operation

Parameters:

consistency - the consistency level

setReplicaId

public Query setReplicaId(int Id)

Specify region replica id where Query will fetch data from. Use this together with setConsistency(Consistency) passing Consistency.TIMELINE to read data from a specific replicaId.
Expert: This is an advanced API exposed. Only use it if you know what you are doing

getReplicaId

public int getReplicaId()

Returns region replica id where Query will fetch data from.

Returns:

region replica id or -1 if not set.

setIsolationLevel

public Query setIsolationLevel(IsolationLevel level)

Set the isolation level for this query. If the isolation level is set to READ_UNCOMMITTED, then this query will return data from committed and uncommitted transactions. If the isolation level is set to READ_COMMITTED, then this query will return data from committed transactions only. If a isolation level is not explicitly set on a Query, then it is assumed to be READ_COMMITTED.

Parameters:

level - IsolationLevel for this query

setQueryMetricsEnabled

public Query setQueryMetricsEnabled(boolean enabled)

Enables the return of QueryMetrics alongside the corresponding result(s) for this query

This is intended for advanced users who need result-granular, server-side metrics

Does not work with calls to Table.exists(Get) and Table.exists(List)

Parameters:

enabled - true to enable collection of per-result query metrics false to disable metrics collection (resulting in null metrics)

isQueryMetricsEnabled

public boolean isQueryMetricsEnabled()

Returns whether query metrics are enabled

Returns:

true if query metrics are enabled, false otherwise

getIsolationLevel

public IsolationLevel getIsolationLevel()

Returns The isolation level of this query. If no isolation level was set for this query object, then it returns READ_COMMITTED.

setLoadColumnFamiliesOnDemand

public Query setLoadColumnFamiliesOnDemand(boolean value)

Set the value indicating whether loading CFs on demand should be allowed (cluster default is false). On-demand CF loading doesn't load column families until necessary, e.g. if you filter on one column, the other column family data will be loaded only for the rows that are included in result, not all rows like in normal case. With column-specific filters, like SingleColumnValueFilter w/filterIfMissing == true, this can deliver huge perf gains when there's a cf with lots of data; however, it can also lead to some inconsistent results, as follows: - if someone does a concurrent update to both column families in question you may get a row that never existed, e.g. for { rowKey = 5, { cat_videos => 1 }, { video => "my cat" } } someone puts rowKey 5 with { cat_videos => 0 }, { video => "my dog" }, concurrent scan filtering on "cat_videos == 1" can get { rowKey = 5, { cat_videos => 1 }, { video => "my dog" } }. - if there's a concurrent split and you have more than 2 column families, some rows may be missing some column families.

getLoadColumnFamiliesOnDemandValue

public Boolean getLoadColumnFamiliesOnDemandValue()

Get the raw loadColumnFamiliesOnDemand setting; if it's not set, can be null.

doLoadColumnFamiliesOnDemand

public boolean doLoadColumnFamiliesOnDemand()

Get the logical value indicating whether on-demand CF loading should be allowed.

setColumnFamilyTimeRange

public Query setColumnFamilyTimeRange(byte[] cf,
                                      long minStamp,
                                      long maxStamp)

Get versions of columns only within the specified timestamp range, [minStamp, maxStamp) on a per CF bases. Note, default maximum versions to return is 1. If your time range spans more than one version and you want all versions returned, up the number of versions beyond the default. Column Family time ranges take precedence over the global time range.

Parameters:

cf - the column family for which you want to restrict

minStamp - minimum timestamp value, inclusive

maxStamp - maximum timestamp value, exclusive

getColumnFamilyTimeRange

public Map<byte[],TimeRange> getColumnFamilyTimeRange()

Returns A map of column families to time ranges