Accumulo-Scala

Accumulo-Scala is a light wrapper to provide a fluent api for reading data from Apache Accumulo in Scala.

Design Goals

• Provide a fluent API
• Avoid needing to close resources explicitly
• Embrace Scala!

Usage

1. import com.tetra.accumulo_scala.ConnectorOps._
2. val connector = instance.getConnector(user, passwordToken)
3. connector scan ...

Examples

scan table 'abc' from 'a' to 'z'

connector scan "abc" from "a" to "z" foreach { e => 
  //do something with each entry ...
}

scan table 'abc' for multiple ids

connector scan "abc" in List("a", "b", "c") foreach { e =>
  //do something with each entry ...
}

scan table 'abc' for only family f and qualifier q

connector scan "abc" filter "f:q" foreach { e =>
  //do something with each entry ...
}

Settings

• com.tetra.accumulo_scala.auths (DEFAULT: Auths.Empty)
• com.tetra.accumulo_scala.auths.delim (DEFAULT: ',')
• com.tetra.accumulo_scala.fq.delim (DEFAULT: ':')
• com.tetra.accumulo_scala.strict (DEFAULT: false)

FAQ (sort of ...)

How many people actually asked any of these questions?

zero

What if I want to use a BatchScanner?

Then you can ask for a parallel implementation using par.

scan table 'abc' par 5 foreach { e => ... }

What if I only want the first 10? Shouldn't there be a limit like in SQL?

Here is an example of where we embrace scala.

scan table 'abc' take 10  foreach { e => ... }

What if I want to skip the first 10? Shouldn't there be a skip like in SQL?

Here, Scala can help ... but eventually we would like to add a server-side iterator for this.

scan table 'abc' drop 10 foreach { e => ... }

I have an index table and a data table, how is this going to help me?

Ask and you shall receive!

connector scan "data" in (connector scan "index" from "a" to "b" map(...)) foreach { e => 
  ... 
}

Is there an easy way to see count how many entries are in my results?

Sure is!

connector.scan("abc").foldLeft(0)((count,_) => count+1)

Can this be used from Java?

I guess, if you really want to ...

Connector connector = instance.getConnector("", new PasswordToken());
ConnectorOps conn = new ConnectorOps(connector);
CloseableIterator<Entry<Key, Value>> ci = conn.scan("abc").from(new Key("a")).to(new Key("b"));
try {
  Entry<Key, Value> e;
  while(ci.hasNext()) {
    e = ci.next();
    //do something
  }
} finally {
  ci.close();
}

License

Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html)

Links

• https://accumulo.apache.org/
• http://www.scala-lang.org/api/current/#package