Connection (Apache HBase 2.5.0 API)

All Superinterfaces:

org.apache.hadoop.hbase.Abortable, AutoCloseable, Closeable
```
@InterfaceAudience.Public
public interface Connection
extends org.apache.hadoop.hbase.Abortable, Closeable
```
A cluster connection encapsulating lower level individual connections to actual servers and a connection to zookeeper. Connections are instantiated through the ConnectionFactory class. The lifecycle of the connection is managed by the caller, who has to close() the connection to release the resources.
The connection object contains logic to find the master, locate regions out on the cluster, keeps a cache of locations and then knows how to re-calibrate after they move. The individual connections to servers, meta cache, zookeeper connection, etc are all shared by the Table and Admin instances obtained from this connection.
Connection creation is a heavy-weight operation. Connection implementations are thread-safe, so that the client can create a connection once, and share it with different threads. Table and Admin instances, on the other hand, are light-weight and are not thread-safe. Typically, a single connection per client application is instantiated and every thread will obtain its own Table instance. Caching or pooling of Table and Admin is not recommended.

Since:

0.99.0

See Also:

ConnectionFactory

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`void`	`clearRegionLocationCache()` Clear all the entries in the region location cache, for all the tables.
`void`	`close()`
`Admin`	`getAdmin()` Retrieve an Admin implementation to administer an HBase cluster.
`BufferedMutator`	`getBufferedMutator(BufferedMutatorParams params)` Retrieve a `BufferedMutator` for performing client-side buffering of writes.
`BufferedMutator`	`getBufferedMutator(TableName tableName)` Retrieve a `BufferedMutator` for performing client-side buffering of writes.
`default String`	`getClusterId()` Returns the cluster ID unique to this HBase cluster.
`org.apache.hadoop.conf.Configuration`	`getConfiguration()` Returns Configuration instance being used by this Connection instance.
`RegionLocator`	`getRegionLocator(TableName tableName)` Retrieve a RegionLocator implementation to inspect region information on a table.
`default Table`	`getTable(TableName tableName)` Retrieve a Table implementation for accessing a table.
`default Table`	`getTable(TableName tableName, ExecutorService pool)` Retrieve a Table implementation for accessing a table.
`TableBuilder`	`getTableBuilder(TableName tableName, ExecutorService pool)` Returns an `TableBuilder` for creating `Table`.
`boolean`	`isClosed()` Returns whether the connection is closed or not.

Methods inherited from interface org.apache.hadoop.hbase.Abortable
abort, abort, isAborted

- Method Detail
  - getConfiguration
```
org.apache.hadoop.conf.Configuration getConfiguration()
```
    Returns Configuration instance being used by this Connection instance.
  - getTable
```
default Table getTable(TableName tableName)
                throws IOException
```
    Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.
    The caller is responsible for calling Table.close() on the returned table instance.
    Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the table does not exist only when the first operation is attempted.
    
    Parameters:
    
    tableName - the name of the table
    
    Returns:
    
    a Table to use for interactions with this table
    
    Throws:
    
    IOException
  - getTable
```
default Table getTable(TableName tableName,
                       ExecutorService pool)
                throws IOException
```
    Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.
    The caller is responsible for calling Table.close() on the returned table instance.
    Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the table does not exist only when the first operation is attempted.
    
    Parameters:
    
    tableName - the name of the table
    
    pool - The thread pool to use for batch operations, null to use a default pool.
    
    Returns:
    
    a Table to use for interactions with this table
    
    Throws:
    
    IOException
  - getBufferedMutator
```
BufferedMutator getBufferedMutator(TableName tableName)
                            throws IOException
```
    Retrieve a BufferedMutator for performing client-side buffering of writes. The BufferedMutator returned by this method is thread-safe. This accessor will create a new ThreadPoolExecutor and will be shutdown once we close the BufferedMutator. This object can be used for long lived operations.
    
    The caller is responsible for calling BufferedMutator.close() on the returned BufferedMutator instance.
    
    Parameters:
    
    tableName - the name of the table
    
    Returns:
    
    a BufferedMutator for the supplied tableName.
    
    Throws:
    
    IOException
  - getBufferedMutator
```
BufferedMutator getBufferedMutator(BufferedMutatorParams params)
                            throws IOException
```
    Retrieve a BufferedMutator for performing client-side buffering of writes. The BufferedMutator returned by this method is thread-safe. This object can be used for long lived table operations. If user passes ThreadPool in BufferedMutatorParams then we will use that otherwise we will create for the user. For user specified ThreadPool, it is the user's responsibility to shutdown. For ThreadPool created by us, we will shutdown when user calls BufferedMutator.close(). The caller is responsible for calling BufferedMutator.close() on the returned BufferedMutator instance.
    
    Parameters:
    
    params - details on how to instantiate the BufferedMutator.
    
    Returns:
    
    a BufferedMutator for the supplied tableName.
    
    Throws:
    
    IOException
  - getRegionLocator
```
RegionLocator getRegionLocator(TableName tableName)
                        throws IOException
```
    Retrieve a RegionLocator implementation to inspect region information on a table. The returned RegionLocator is not thread-safe, so a new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned RegionLocator is neither required nor desired.
    The caller is responsible for calling Closeable.close() on the returned RegionLocator instance. RegionLocator needs to be unmanaged
    
    Parameters:
    
    tableName - Name of the table who's region is to be examined
    
    Returns:
    
    A RegionLocator instance
    
    Throws:
    
    IOException
  - clearRegionLocationCache
```
void clearRegionLocationCache()
```
    Clear all the entries in the region location cache, for all the tables.
    If you only want to clear the cache for a specific table, use RegionLocator.clearRegionLocationCache().
    This may cause performance issue so use it with caution.
  - getAdmin
```
Admin getAdmin()
        throws IOException
```
    Retrieve an Admin implementation to administer an HBase cluster. The returned Admin is not guaranteed to be thread-safe. A new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned Admin is not recommended.
    The caller is responsible for calling Admin.close() on the returned Admin instance.
    
    Returns:
    
    an Admin instance for cluster administration
    
    Throws:
    
    IOException
  - close
```
void close()
    throws IOException
```
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
    
    Throws:
    
    IOException
  - isClosed
```
boolean isClosed()
```
    Returns whether the connection is closed or not.
    
    Returns:
    
    true if this connection is closed
  - getTableBuilder
```
TableBuilder getTableBuilder(TableName tableName,
                             ExecutorService pool)
```
    Returns an TableBuilder for creating Table.
    
    Parameters:
    
    tableName - the name of the table
    
    pool - the thread pool to use for requests like batch and scan
  - getClusterId
```
default String getClusterId()
```
    Returns the cluster ID unique to this HBase cluster.
    The default implementation is added to keep client compatibility.

Interface Connection

Method Summary

Methods inherited from interface org.apache.hadoop.hbase.Abortable

Method Detail

getConfiguration

getTable

getTable

getBufferedMutator

getBufferedMutator

getRegionLocator

clearRegionLocationCache

getAdmin

close

isClosed

getTableBuilder

getClusterId