access sql database as nosql (couchbase)

Question

I hope to access sql database as the way of nosql key-value pairs/document. This is for future upgrade if user amount increases a lot, I can migrate from sql to nosql immediately while application code changes nothing. Of course I can write the api/solution by myself, just wonder if there is any person has done same thing as I said before and published the solution.

Your comment welcome

Answer 1

While I agree with everything scalabilitysolved has said, there is an interesting feature in the offing for Postgres, scheduled for the 9.4 Postgres release, namely, jsonb: http://www.postgresql.org/docs/devel/static/datatype-json.html with some interesting indexing and query possibilities. I mention this as you tagged Mongodb and Couchbase, both of which use JSON (well, technically BSON in Mongodb's case).

Of course, querying, sharding, replication, ACID guarantees, etc will still be totally different between Postgres (or any other traditional RDBMS) and any document-based NoSQL solution and migrations between any two RDBMS tends to be quite painful, let alone between an RDBMS and a NoSQL data store. However, jsonb looks quite promising as a potential half-way house between two of the major paradigms of data storage.

On the other hand, every release of MongoDB brings enhancements to the aggregation pipeline, which is certainly something that seems to appeal to people used to the flexibility that SQL offers and less "alien" than distributed map/reduce jobs. So, it seems reasonable to conclude that there will continue to be cross pollination.

See Explanation of JSONB introduced by PostgreSQL for some further insights into jsonb.

Answer 2

No no no, do not consider this, it's a really bad idea. Pick either a RDBMS or NoSQL solution based upon how your data is modelled and your usage patterns. Converting from one to another is going to be painful and especially if your 'user amount increases a lot'.

Let's face it, either approach would deal with a large increase in usage and both would benefit more from specific optimizations to their database then simply swapping because one 'scales more'.

If your data model fits RDBMS and it needs to perform better than analyze your queries, check your indexes are optimized and look into caching and better data pattern access.

If your data model fits a NoSQL database then as your dataset grows you can add additional nodes (Couchbase),caching expensive map reduce jobs and again optimizing your data pattern access.

In summary, pick either SQL or NoSQL dependent on your data needs, don't just assume that NoSQL is a magic bullet as with easier scaling comes a much less flexible querying model.