Question

I have large data set, which I want to query. The query does not change but the underlying data does. From what I read, I could construct a “view” and query it. Also, I read that Couch DB knows how to update the view when data is changed so I assume querying the view again would be still fast.

My questions are, do I understand CounchDB’s views correctly? I don’t need any other feature of CouchDB, I don’t even need SQL, all I want is fast same query over changing data. Could I use something else? If I would use, say, good old MySQL would it really be slower than CouchDB (read: in the above scenario, how would various DBs approximately perform?).

Answer 1

I don’t think anyone can answer your question given the information you have provided.

Indexes in a relational database are analogous to CouchDB views. In both cases, they store a pre-sorted instance of the data and the database keeps that instance in sync with the canonical data. Both types of database transparently use the index/view to speed up subsequent queries of the form that the index/view was designed for.

Without indexes/views, queries must scan the whole collection of n records of data and they execute in O(n) time. When a query benefits from an indexes/views, it executes in O(log n) time.

But that’s speaking very broadly of the performance curve with respect to the volume of data. A given database could have such speedy performance in certain cases that it out-performs another product no matter what. It’s hard to make generalizations that brand X is always faster than brand Y. The only way to be sure about a specific case is to try that case in both databases and measure the performance.