org.apache.hadoop.hbase.client

类 Get

java.lang.Object

org.apache.hadoop.hbase.client.Operation

org.apache.hadoop.hbase.client.OperationWithAttributes

org.apache.hadoop.hbase.client.Query

org.apache.hadoop.hbase.client.Get

所有已实现的接口:

Comparable<Row>, Attributes, Row

@InterfaceAudience.Public
@InterfaceStability.Stable
public class Get
extends Query
implements Row, Comparable<Row>

Used to perform Get operations on a single row.

To get everything for a row, instantiate a Get object with the row to get. To further narrow the scope of what to Get, use the methods below.

To get all columns from specific families, execute addFamily for each family to retrieve.

To get specific columns, execute addColumn for each column to retrieve.

To only retrieve columns within a specific range of version timestamps, execute setTimeRange.

To only retrieve columns with a specific timestamp, execute setTimestamp.

To limit the number of versions of each column to be returned, execute setMaxVersions.

To add a filter, call setFilter.

字段概要

从类继承的字段 org.apache.hadoop.hbase.client.Query

colFamTimeRangeMap, consistency, filter, loadColumnFamiliesOnDemand, targetReplicaId

从类继承的字段 org.apache.hadoop.hbase.client.OperationWithAttributes

ID_ATRIBUTE

构造器概要

构造器

构造器和说明
Get(byte[] row) Create a Get operation for the specified row.
Get(Get get) Copy-constructor

方法概要

方法

限定符和类型	方法和说明
Get	addColumn(byte[] family, byte[] qualifier) Get the column from the specific family with the specified qualifier.
Get	addFamily(byte[] family) Get all columns from the specified family.
int	compareTo(Row other)
boolean	equals(Object obj)
Set<byte[]>	familySet() Method for retrieving the keys in the familyMap
boolean	getCacheBlocks() Get whether blocks should be cached for this Get.
Map<byte[],NavigableSet<byte[]>>	getFamilyMap() Method for retrieving the get's familyMap
Map<String,Object>	getFingerprint() Compile the table and column family (i.e. schema) information into a String.
int	getMaxResultsPerColumnFamily() Method for retrieving the get's maximum number of values to return per Column Family
int	getMaxVersions() Method for retrieving the get's maximum number of version
byte[]	getRow() Method for retrieving the get's row
int	getRowOffsetPerColumnFamily() Method for retrieving the get's offset per row per column family (#kvs to be skipped)
TimeRange	getTimeRange() Method for retrieving the get's TimeRange
boolean	hasFamilies() Method for checking if any families have been inserted into this Get
int	hashCode()
boolean	isCheckExistenceOnly()
boolean	isClosestRowBefore()
int	numFamilies() Method for retrieving the number of families to get from
Get	setACL(Map<String,Permission> perms)
Get	setACL(String user, Permission perms)
Get	setAttribute(String name, byte[] value) Sets an attribute.
Get	setAuthorizations(Authorizations authorizations) Sets the authorizations to be used by this Query
Get	setCacheBlocks(boolean cacheBlocks) Set whether blocks should be cached for this Get.
Get	setCheckExistenceOnly(boolean checkExistenceOnly)
Get	setClosestRowBefore(boolean closestRowBefore)
Get	setColumnFamilyTimeRange(byte[] cf, long minStamp, long maxStamp) Get versions of columns only within the specified timestamp range, [minStamp, maxStamp) on a per CF bases.
Get	setConsistency(Consistency consistency) Sets the consistency level for this operation
Get	setFilter(Filter filter) Apply the specified server-side filter when performing the Query.
Get	setId(String id) This method allows you to set an identifier on an operation.
Get	setIsolationLevel(IsolationLevel level) Set the isolation level for this query.
Get	setLoadColumnFamiliesOnDemand(boolean value) Set the value indicating whether loading CFs on demand should be allowed (cluster default is false).
Get	setMaxResultsPerColumnFamily(int limit) Set the maximum number of values to return per row per Column Family
Get	setMaxVersions() Get all available versions.
Get	setMaxVersions(int maxVersions) Get up to the specified number of versions of each column.
Get	setPriority(int priority)
Get	setReplicaId(int Id) Specify region replica id where Query will fetch data from.
Get	setRowOffsetPerColumnFamily(int offset) Set offset for the row per Column Family.
Get	setTimeRange(long minStamp, long maxStamp) Get versions of columns only within the specified timestamp range, [minStamp, maxStamp).
Get	setTimeStamp(long timestamp) Get versions of columns with the specified timestamp.
Map<String,Object>	toMap(int maxCols) Compile the details beyond the scope of getFingerprint (row, columns, timestamps, etc.) into a Map along with the fingerprinted information.

从类继承的方法 org.apache.hadoop.hbase.client.Query

doLoadColumnFamiliesOnDemand, getACL, getAuthorizations, getColumnFamilyTimeRange, getConsistency, getFilter, getIsolationLevel, getLoadColumnFamiliesOnDemandValue, getReplicaId

从类继承的方法 org.apache.hadoop.hbase.client.OperationWithAttributes

getAttribute, getAttributeSize, getAttributesMap, getId, getPriority

从类继承的方法 org.apache.hadoop.hbase.client.Operation

toJSON, toJSON, toMap, toString, toString

从类继承的方法 java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

构造器详细资料

Get

public Get(byte[] row)

Create a Get operation for the specified row.

If no further operations are done, this will get the latest version of all columns in all families of the specified row.

参数:

row - row key

Get

public Get(Get get)

Copy-constructor

参数:

get -

方法详细资料

isCheckExistenceOnly

public boolean isCheckExistenceOnly()

setCheckExistenceOnly

public Get setCheckExistenceOnly(boolean checkExistenceOnly)

isClosestRowBefore

public boolean isClosestRowBefore()

setClosestRowBefore

public Get setClosestRowBefore(boolean closestRowBefore)

addFamily

public Get addFamily(byte[] family)

Get all columns from the specified family.

Overrides previous calls to addColumn for this family.

参数:

family - family name

返回:

the Get object

addColumn

public Get addColumn(byte[] family,
            byte[] qualifier)

Get the column from the specific family with the specified qualifier.

Overrides previous calls to addFamily for this family.

参数:

family - family name

qualifier - column qualifier

返回:

the Get objec

setTimeRange

public Get setTimeRange(long minStamp,
               long maxStamp)
                 throws IOException

Get versions of columns only within the specified timestamp range, [minStamp, maxStamp).

参数:

minStamp - minimum timestamp value, inclusive

maxStamp - maximum timestamp value, exclusive

返回:

this for invocation chaining

抛出:

IOException

setTimeStamp

public Get setTimeStamp(long timestamp)
                 throws IOException

Get versions of columns with the specified timestamp.

参数:

timestamp - version timestamp

返回:

this for invocation chaining

抛出:

IOException

setColumnFamilyTimeRange

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

从类复制的说明: Query

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.

覆盖:

setColumnFamilyTimeRange 在类中 Query

参数:

cf - the column family for which you want to restrict

minStamp - minimum timestamp value, inclusive

maxStamp - maximum timestamp value, exclusive

返回:

this

setMaxVersions

public Get setMaxVersions()

Get all available versions.

返回:

this for invocation chaining

setMaxVersions

public Get setMaxVersions(int maxVersions)
                   throws IOException

Get up to the specified number of versions of each column.

参数:

maxVersions - maximum versions for each column

返回:

this for invocation chaining

抛出:

IOException - if invalid number of versions

setLoadColumnFamiliesOnDemand

public Get setLoadColumnFamiliesOnDemand(boolean value)

从类复制的说明: Query

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.

覆盖:

setLoadColumnFamiliesOnDemand 在类中 Query

setMaxResultsPerColumnFamily

public Get setMaxResultsPerColumnFamily(int limit)

Set the maximum number of values to return per row per Column Family

参数:

limit - the maximum number of values returned / row / CF

返回:

this for invocation chaining

setRowOffsetPerColumnFamily

public Get setRowOffsetPerColumnFamily(int offset)

Set offset for the row per Column Family. This offset is only within a particular row/CF combination. It gets reset back to zero when we move to the next row or CF.

参数:

offset - is the number of kvs that will be skipped.

返回:

this for invocation chaining

setFilter

public Get setFilter(Filter filter)

从类复制的说明: Query

Apply the specified server-side filter when performing the Query. Only Filter.filterKeyValue(Cell) is called AFTER all tests for ttl, column match, deletes and max versions have been run.

覆盖:

setFilter 在类中 Query

参数:

filter - filter to run on the server

返回:

this for invocation chaining

setCacheBlocks

public Get setCacheBlocks(boolean cacheBlocks)

Set whether blocks should be cached for this Get.

This is true by default. When true, default settings of the table and family are used (this will never override caching blocks if the block cache is disabled for that family or entirely).

参数:

cacheBlocks - if false, default settings are overridden and blocks will not be cached

getCacheBlocks

public boolean getCacheBlocks()

Get whether blocks should be cached for this Get.

返回:

true if default caching should be used, false if blocks should not be cached

getRow

public byte[] getRow()

Method for retrieving the get's row

指定者:

getRow 在接口中 Row

返回:

row

getMaxVersions

public int getMaxVersions()

Method for retrieving the get's maximum number of version

返回:

the maximum number of version to fetch for this get

getMaxResultsPerColumnFamily

public int getMaxResultsPerColumnFamily()

Method for retrieving the get's maximum number of values to return per Column Family

返回:

the maximum number of values to fetch per CF

getRowOffsetPerColumnFamily

public int getRowOffsetPerColumnFamily()

Method for retrieving the get's offset per row per column family (#kvs to be skipped)

返回:

the row offset

getTimeRange

public TimeRange getTimeRange()

Method for retrieving the get's TimeRange

返回:

timeRange

familySet

public Set<byte[]> familySet()

Method for retrieving the keys in the familyMap

返回:

keys in the current familyMap

numFamilies

public int numFamilies()

Method for retrieving the number of families to get from

返回:

number of families

hasFamilies

public boolean hasFamilies()

Method for checking if any families have been inserted into this Get

返回:

true if familyMap is non empty false otherwise

getFamilyMap

public Map<byte[],NavigableSet<byte[]>> getFamilyMap()

Method for retrieving the get's familyMap

返回:

familyMap

getFingerprint

public Map<String,Object> getFingerprint()

Compile the table and column family (i.e. schema) information into a String. Useful for parsing and aggregation by debugging, logging, and administration tools.

指定者:

getFingerprint 在类中 Operation

返回:

Map

toMap

public Map<String,Object> toMap(int maxCols)

Compile the details beyond the scope of getFingerprint (row, columns, timestamps, etc.) into a Map along with the fingerprinted information. Useful for debugging, logging, and administration tools.

指定者:

toMap 在类中 Operation

参数:

maxCols - a limit on the number of columns output prior to truncation

返回:

Map

compareTo

public int compareTo(Row other)

指定者:

compareTo 在接口中 Comparable<Row>

hashCode

public int hashCode()

覆盖:

hashCode 在类中 Object

equals

public boolean equals(Object obj)

覆盖:

equals 在类中 Object

setAttribute

public Get setAttribute(String name,
               byte[] value)

从接口复制的说明: Attributes

Sets an attribute. In case value = null attribute is removed from the attributes map. Attribute names starting with _ indicate system attributes.

指定者:

setAttribute 在接口中 Attributes

覆盖:

setAttribute 在类中 OperationWithAttributes

参数:

name - attribute name

value - attribute value

setId

public Get setId(String id)

从类复制的说明: OperationWithAttributes

This method allows you to set an identifier on an operation. The original motivation for this was to allow the identifier to be used in slow query logging, but this could obviously be useful in other places. One use of this could be to put a class.method identifier in here to see where the slow query is coming from.

覆盖:

setId 在类中 OperationWithAttributes

参数:

id - id to set for the scan

setAuthorizations

public Get setAuthorizations(Authorizations authorizations)

从类复制的说明: Query

Sets the authorizations to be used by this Query

覆盖:

setAuthorizations 在类中 Query

setACL

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

覆盖:

setACL 在类中 Query

参数:

perms - A map of permissions for a user or users

setACL

public Get setACL(String user,
         Permission perms)

覆盖:

setACL 在类中 Query

参数:

user - User short name

perms - Permissions for the user

setConsistency

public Get setConsistency(Consistency consistency)

从类复制的说明: Query

Sets the consistency level for this operation

覆盖:

setConsistency 在类中 Query

参数:

consistency - the consistency level

setReplicaId

public Get setReplicaId(int Id)

从类复制的说明: Query

Specify region replica id where Query will fetch data from. Use this together with Query.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

覆盖:

setReplicaId 在类中 Query

setIsolationLevel

public Get setIsolationLevel(IsolationLevel level)

从类复制的说明: Query

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.

覆盖:

setIsolationLevel 在类中 Query

参数:

level - IsolationLevel for this query

setPriority

public Get setPriority(int priority)

覆盖:

setPriority 在类中 OperationWithAttributes