Thread: JDBC4 Binary Mode with Arrays

Sorry for the cross post, I put this on general first:

In my current application I am sending a lot of data to/from the DB with JDBC, and specifically arrays of Double. (or even Double[][]).
I have been converting everything into a string representation of the array with StringBuffer, which eats a lot of memory.

I note that there is this web page:
http://wiki.postgresql.org/wiki/JDBC-BinaryTransfer

Which made me think I might be saved.

After trying out the JDBC4 driver in DBCP, I see that Connection.createArray(...) still just creates a big string under the covers. Is that the expected behavior? Am I doing it wrong?
Will the String get converted to binary representation again before hitting the wire?

Regards,
-JD

On Fri, 1 Apr 2011, bubba postgres wrote:

> In my current application I am sending a lot of data to/from the DB with
> JDBC, and specifically arrays of Double. (or even Double[][]).
> I have been converting everything into a string representation of the array
> with StringBuffer, which eats a lot of memory.
>
> I note that there is this web page:
> http://wiki.postgresql.org/wiki/JDBC-BinaryTransfer
>
> After trying out the JDBC4 driver in DBCP, I see that
> Connection.createArray(...) still just creates a big string under the
> covers. Is that the expected behavior? Am I doing it wrong?
> Will the String get converted to binary representation again before hitting
> the wire?
>

That page is about work in progress, not about the behavior of the
production driver.  So you are correct that the transfer is being done
with string representation currently.

Kris Jurka

bubba postgres <bubba.postgres@gmail.com> Friday 01 April 2011 20:44:32
> Sorry for the cross post, I put this on general first:
>
> In my current application I am sending a lot of data to/from the DB with
> JDBC, and specifically arrays of Double. (or even Double[][]).
> I have been converting everything into a string representation of the array
> with StringBuffer, which eats a lot of memory.
>
> I note that there is this web page:
> http://wiki.postgresql.org/wiki/JDBC-BinaryTransfer
>
> Which made me think I might be saved.
>
> After trying out the JDBC4 driver in DBCP, I see that
> Connection.createArray(...) still just creates a big string under the
> covers. Is that the expected behavior? Am I doing it wrong?
> Will the String get converted to binary representation again before hitting
> the wire?
>
> Regards,
> -JD
I developed some experimental driver, with support for binary mode, and it's
only supported mode right now. I'll be glad if You try it:
http://softperience.eu/pages/cmn/ngpgjdbc.xhtml

Regards,
Radoslaw Smogura