About Sharkbite

Sharkbite is an HDFS and native client for key/value stores. With initial support for Apache Accumulo Accumulo, the design can and has been used to support other key/value stores. Development began in 2014 and has slowly evolved. there is no structural specificity to Accumulo despite being the base implementation. Despite this the examples below will look very much like Accumulo due to aliasing. This is intentional.

Capabilities That will be supported in V1.0 :

• Works with Accumulo 1.6.x, 1.7.x, 1.8.x, 1.9.x and 2.x
• Read/Write : Reading and writing data to Accumulo is currently supported.
• Table Operations : Most table operations are currently supported. This includes the fate operations that the normal Accumulo client performs.
• Security Operations : Most security operations are implemented. Please let us know of any gaps.

About the name

Sharkbite’s name originated from design as a connector that abstracted components in which we tightly coupled and gripped interfaces of the underlying datastore. With an abstraction layer for access, and using cross compatible objects, the underlying interfaces are heavily coupled to each database. As a result, Sharkbite became a fitting name since interfaces exist to abstract the high coupling that exists within implementations of the API.

Installing

This python client can be installed via pip install sharkbite

A Python example is included. This is your primary example of the Python bound sharkbite library.

Sharkbite supports async iteration A simple example is provided.

Features

HDFS Client

Sharkbite supports a limited HDFS client. As this functionality grows so will the capabilities. Version 0.7 will support a complete HDFS client. Since Sharkbite it built as a python bindings around a C++ Client, the python client will mature slightly behind the C++ client, hence the delta with building this into V 0.7

Version Detection

Sharkbite detects the version of Apache Accumulo. Therefore you will be able to simply create a connector to the zookeeper instance.

Hedged Reads

Sharkbite supports hedged reads ( executing scans against RFiles when they can be accessed ) concurrently with Accumulo RPC scans. The first executor to complete will return your results. This feature is in beta and not suggested for production environments.

Enable it with the following option:

    import pysharkbite as sharkbite

    connector = sharkbite.AccumuloConnector(user, zk)

table_operations = connector.tableOps(table)

    scanner = table_operations.createScanner(auths, 2)

range = sharkbite.Range("myrow")

scanner.addRange( range )

### enable the beta option of hedged reads

scanner.setOption( sharkbite.ScannerOptions.HedgedReads )

resultset = scanner.getResultSet()

for keyvalue in resultset:
    key = keyvalue.getKey()
    value = keyvalue.getValue()

Python Iterators

We now support a beta version of python iterators. By using the cmake option PYTHON_ITERATOR_SUPPORT ( cmake -DPYTHON_ITERATOR_SUPPORT=ON ) we will build the necessary infrastructure to support python iterators

Iterators can be defined as single function lambdas or by implementing the seek or next methods.

The first example implements the seek and onNext methods. seek is optional if you don’t wish to adjust the range. Once keys are being iterated you may get the top key. You may call iterator.next() after or the infrastructure will do that for you.

class myIterator:
  def seek(iterator,soughtRange):
    range = Range("a")
    iterator.seek(range)


  def onNext(iterator):
    if (iterator.hasTop()):
        kv = KeyValue()
          key = iterator.getTopKey()
          cf = key.getColumnFamily()
          value = iterator.getTopValue()
          key.setColumnFamily("oh changed " + cf)
          iterator.next()
          return KeyValue(key,value)
    else:
      return None

If this is defined in a separate file, you may use it with the following code snippet

with open('test.iter', 'r') as file:
 iterator = file.read()
## name, iterator text, priority
 iterator = pysharkbite.PythonIterator("PythonIterator",iteratortext,100)
 scanner.addIterator(iterator)

Alternative you may use lambdas. The lambda you provide will be passed the KeyValue ( getKey() and getValue() return the constituent parts). A partial code example of setting it up is below. You may return a Key or KeyValue object. If you return the former an empty value will be return ed.

## define only the name and priority
iterator = pysharkbite.PythonIterator("PythonIterator",100)
## define a lambda to ajust the column family.
iterator = iterator.onNext("lambda x : Key( x.getKey().getRow(), 'new cf', x.getKey().getColumnQualifier()) ")

scanner.addIterator(iterator)

You may either define a python iterator as a text implementation or a lambda. Both cannot be used simulaneously.

[accumulo]: https://accumulo.apache.org