Question

So I’m aware of some relative differences i.e., the ResultSet has an ‘open connection’ to the database whereas a RowSet works in a ‘disconnected’ fashion.

But that’s pretty much what I understand (may be incorrect):

My question is then this – under what circumstances is one preferable over the other? What are each of their strengths/weaknesses?

• From what I feel a RowSet, working in
  disconnected mode especially for
  "read-only" queries, would have
  better performance in a highly
  concurrent system. Is that correct?
  If that’s the case is it safe to say
  RowSet is always preferable to
  ResultSet for readonly queries?

• If I’m correct iterating over the
  RowSet doesn’t throw SQL Exceptions,
  but is that a benefit? The other
  being that RowSet is serializable.
  But my concern is primarily from a
  performance perspective what would be
  the choice?

• But does it even matter for
  read-write queries?? Can you sync the
  ResultSet back to the DB? (I’m not
  sure if that’s possible (It may be
  and I just can’t recollect or google
  it well enough 🙂 It’s been a while
  with raw JDBC…

Any ideas? There are some missing gaps in my knowledge as is evident 🙂

The reason I ask is I’d like to choose between implementing Spring-JDBC’s ResultSetExtractor Interface versus return an SqlRowSet when processing some data. This question just got me curious to how to decide what to choose when, other than tossing a coin 🙂

Answer 1

RowSet

RowSet is almost always the right choice, it is more full featured and has all the benefits you listed as well as having specialized implementations for special purposes, like the disconnected CachedRowSet which is what I always use when the data will fit into memory, so I can release the connection back to the pool as quickly as possible to be reused.

ResultSet should never be part of a public contract.

A connected ResultSet/Rowset should never escape the method or at worst the object that created them. At least with a RowSet you can disconnect it and the client doesn’t have to care about the implementation. *Unless you are writing JDBC specific library code that interacts or relies on ResultSet specific features or contracts.

If you are just transferring the results of a query, JDBC specific classes should be part of your public contract.

Ideally you want to materialize RowSet/ResultSet contents to typesafe Domain Objects to pass around.

In most cases you want to materialize a List/Set of domain objects to manipulate and work with instead of coupling your code directly to the JDBC api.

Many modern takes on a ResultSetMapper<T> class exist to handle generating typesafe domain instances using a Visitor pattern because this is the idiomatic way of doing things.