BigTable and HBase explained

Since Google AppEngine is up and running BigTable gained quite some popularity as RDBMS alternative. What’s important to understand is that BigTable is _not_ a relational database. What it actually is, is wonderfully explained by this article:

Understanding HBase and BigTable

The article contains some helpful references and is really all you need to get started with BigTable. What I find really helps in understanding is the JSON representation Jim uses:

{
  // ...
  "aaaaa" : {
    "A" : {
      "foo" : {
        15 : "y",
        4 : "m"
      },
      "bar" : {
        15 : "d",
      }
    },
    "B" : {
      "" : {
        6 : "w"
        3 : "o"
        1 : "w"
      }
    }
  },
  // ...
}

So BigTable / HBase is really a map of maps of maps. In the BigTable terminology “aaaaa” is the row key, “A” the column family, “foo” the column name and the integers are some sort of version number. I really recommend to read the article for details.