Database Reference
In-Depth Information
NoSQL category
Typical use cases
Best-known technologies
• Domain can be represented with nodes and rela-
tionships naturally
• Social networks
• Recommendation engines
• Access control lists
• OrientDB
So far in this chapter, you've seen examples of the efficient use of Neo4j to solve graph-
related problems, seen how common real-world problems can be naturally modeled as
graphs, and learned where graph databases and Neo4j in particular sit within the wider
NoSQL space. But there's one key aspect of Neo4j that none of the other NoSQL stores
have—onethat'sveryimportantwhenitcomestotheadoptionofnewstoragetechnologies
in the enterprise world: transactional behavior.
1.7. Neo4j: the ACID-compliant database
TransactionmanagementhasbeenaprominenttalkingpointindiscussionsofNoSQLtech-
nologies since they started to gain popularity. Trading off transactional attributes for in-
creased performance and scalability has been a common approach in nonrelational tech-
nologies that targeted big data. Some (such as BigTable, Cassandra, and CouchDB) opted
to trade off consistency, allowing clients to read stale data in some cases in a distributed
system (eventual consistency). In key-value stores that concentrated on read performance
(such as Memcached), durability of the data wasn't of too much interest. Similarly, atom-
icity on a single-operation level, without the possibility to wrap multiple database opera-
tions within a single transaction, is typical for document-oriented databases.
While each of the approaches mentioned here are valid in specific use cases (such as cach-
ing, high data-read volumes, high load, and concurrency), the lack of ACID-based trans-
action handling is usually the first hurdle when it comes to introducing nonrelational data-
bases to any enterprise or corporate environment. Although they were devised a long time
ago for relational databases, transaction attributes still play an important and fundamental
part in many practical use cases. Neo4j has therefore taken a different approach.
