The links between these records tend to be fixed ahead of time, either as data is entered or when the database parameters are being established. What hierarchical databases once gained in speed by having fixed connections, they lost in flexibility and overall efficiency. And, as computer processors became faster and programming languages more capable, the speed advantage of hierarchical databases became less and less of an advantage. Hierarchical databases were the first databases run on mainframe computers, and as mainframes have given way to more efficient computers, so have hierarchical databases been replaced largely by relational databases. Relational databases .
Relational databases are all the rage in terms of database efficiency and power.
The most important thing to keep in mind about relational databases is that whereas hierarchical databases use fixed relationships between data forms, relational databases are able to compare characteristics of data, fields or records to make new files that may match the criteria of the data retriever. It should be said that, given the range over which relational databases operate, relational databases can tend to be slow. Such indexing can significantly speed up the data delivery of relational databases. Network databases . By this, I mean that one item in a network database can link to a number of data elements, and can itself be linked and be a variety of data elements.