Re: Stream Copy for 8.1 - 8.3dev

Hi again.

Fixed versions of copy patches and drivers are now available at
http://kato.iki.fi/sw/db/postgresql/jdbc/copy/

Unit tests do pass, but I had to postpone any more extensive tests for now.

2007/7/16, Kris Jurka <books@ejurka.com>:
> 1) Your CopyObjects example pays no attention to encoding or escaping.
> Calling getBytes() will give you bytes in the JVM's character set which
> can easily be different than the client_encoding which the driver will
> always set to UTF-8 (for 7.3 and up).  You also have to think about what
> happens when your data contains a null escape, delimiter, or newline
> itself.

Example dropped for now. Once the core implementation is considered
acceptable, I'll add documentation and helper classes.

> 2) I'm not sure it's helpful to have the copy methods throw both an IO and
> SQL exception.  Why not just wrap any IOExceptions inside a SQLException?

Wrapped as suggested.

> 3) What is the purpose of the reuse_buffer parameter?  What is the use
> case for someone wanting a "fresh" buffer every time?

Dropped as unnecessary.

> 4) buildCopyQuery doesn't handle quoting/escaping of identifiers.  By
> providing something like this you're now responsible for all the "hard"
> stuff.  I would leave it out unless you're prepared to do a lot more
> thinking about it.  It also doesn't handle all the possible copy options.
> Perhaps you should split this into core copy functionality and a helper
> class that builds upon it and can provide other useful things (escaping /
> conversion of java objects to pg datatypes).

Dropped as unnecessary.

> 5) The coding in QueryExecutorImpl is unsafe because once you get
> CopyInResponse you loop firing away data without listening for any return
> data.  Consider a table which had a trigger on it which issued a notice
> for each row it received.  If you don't read from the server the server
> will block and then you'll block sending it data.  See the comments in
> core/v3/QueryExecutorImpl near MAX_BUFFERED_QUERIES for more details.

Changed so that data is sent only while the server stays quiet.
(Apparently I should write a test for this.)

> 6) You mix warnings and errors together.  They should be kept separate.

Separated warnings from errors. After succesful recovery from copy
subprotocol state:

- if any errors were catched, they're thrown and warnings get dropped
as a side effect;
- if any warnings got collected, they're thrown, since I'm unsure
about how to handle them.

> 7) When you get CopyResponses and the user hasn't provided the appropriate
> stream you bail leaving the protocol in an unknown state.  You should
> issue a CopyFail and wait for ReadyForQuery so the whole connection isn't
> lost.

Fixed as suggested.

--
Kalle Hallivuori +358-41-5053073 http://korpiq.iki.fi/