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POHow would you represent a relational entity as a single unit of retrievable data in BerkeleyDB?
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copied!<p><a href="http://en.wikipedia.org/wiki/Berkeley_DB" rel="nofollow noreferrer">BerkeleyDB</a> is the database equivalent of a Ruby hashtable or a Python dictionary except that you can store multiple values for a single key. </p> <p><strong>My question is: If you wanted to store a complex datatype in a storage structure like this, how could you go about it?</strong></p> <p>In a normal relational table, if you want to represent a Person, you create a table with columns of particular data types:</p> <pre><code>Person -id:integer -name:string -age:integer -gender:string </code></pre> <p>When it's written out like this, you can see how a person might be understood as a set of key/value pairs: </p> <pre><code>id=1 name="john"; age=18; gender="male"; </code></pre> <p><strong>Decomposing the person into individual key/value pairs (name="john") is easy.</strong></p> <p><strong>But in order to use the BerkeleyDB format to represent a Person, you would need some way of recomposing the person from its constituent key/value pairs.</strong></p> <p><strong>For that, you would need to impose some artificial encapsulating structure to hold a Person together as a unit.</strong></p> <p><strong>Is there a way to do this?</strong></p> <p>EDIT: As Robert Harvey's answer indicates, there is an entity persistence feature in the <a href="http://www.oracle.com/technology/documentation/berkeley-db/je/java/com/sleepycat/persist/model/Entity.html" rel="nofollow noreferrer">Java edition</a> of BerkeleyDB. Unfortunately because I will be connnecting to BerkeleyDB from a Ruby application using <a href="http://github.com/wycats/moneta/tree/master" rel="nofollow noreferrer">Moneta</a>, I will be using the <a href="http://www.oracle.com/technology/products/berkeley-db/db/index.html" rel="nofollow noreferrer">standard edition</a> which I believe requires me to create a custom solution in the absence of this support.</p>

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