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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: maxrows - what does it really mean?
Date Sun, 13 May 2007 19:06:38 GMT
Hi David,

Generally the JDBC spec stays clear of discussing the client-server  
protocol.

The behavior described by the JDBC method is the user-visible  
behavior. There are two roles involved in the behavior, which might  
be implemented by two different providers: the JDBC provider (client)  
and the database provider (server).

The JDBC spec doesn't mandate whether the behavior is implemented by  
one provider or the other. Where the server does have the ability to  
constrain the results there might be a way for the client to tell the  
server of the constraint, via the client-server protocol.

On May 11, 2007, at 3:29 PM, David Van Couvering wrote:

> The behavior I want is to say get 10 rows at a time, with the least
> amount of processing and network overhead wasted on rows that I am not
> interested in yet.  What's the strategy for this?
>
> the setMaxRows() method for Statement says:
>
> "Sets the limit for the maximum number of rows that any ResultSet
> object can contain to the given number. If the limit is exceeded, the
> excess rows are silently dropped."
>
> What I am wondering is, is there any way to tell the *server* to send
> only a certain number of rows, rather than the server processing all
> these rows and the client just dropping them.
>
> Also, how is maxrows related to the fetch size of a ResultSet?

As I understand it, the fetch size relates to the number of rows  
returned by the server to the client for each round trip to the  
database. So theoretically the two numbers are independent. There's  
no specified interaction except for the obvious one: requesting a  
fetch size exceeding the maxrows doesn't make sense since there will  
never be more than maxrows returned, and fetch size would effectively  
be ignored.

Craig
>
> Thanks,
>
> David

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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