[Pgpool-general] Trouble with the JDBC drivers...

[Bryan Varner]

> It seems the code tries to do what you said.  There are many places
> calling pool_create_sent_message().  In my understanding the function
> tries to remember where Parse/Bind messges have been sent. For
> example, Parse() calles like this:
>
> 		msg = pool_create_sent_message('P', len, contents, 0, name, query_context);
>
> Afterward Bind() tries to extract the data:
>
> 	parse_msg = pool_get_sent_message('Q', pstmt_name);
>
> Aafter several lines Bind() calls this.
>
> 	pool_where_to_send(query_context, query_context->original_query,
> 					   query_context->parse_tree);
>
> I think problem is here.
>
> pool_where_to_send() decides to choose node(s) bind messages should be
> sent to. The function has been called when Parse() gets called to
> determine the destination node as well. pool_where_to_send() makes the
> decision by using current condition, inckuding transaction state. And
> Bind() does the same job by calling pool_where_to_send(). But what if
> the condition has been changed between Parse() and Bind()? It is
> possible that desitination node could be different and bind message
> might be sent to a node where parse never gets executed. I think at
> least part of problems you are having comes from this. Bind() should
> not call pool_where_to_send() instead inherits the desitination node
> from Parse() in my opinion.

I've also been able to verify that Execute() will send to destinations 
different from Bind(), and that's when I get invalid portal name errors 
from the backend. I think this is happening at both levels, Bind & Execute.

I agree that the easiest fix here is to simply not invoke 
pool_where_to_send for Bind or Execute, but to inherit where they were 
Parse()ed at.

I had been playing with the idea of re-parsing / re-binding statements 
if there was a mismatch, but I'm not convinced it's the right thing to 
do, or that the overhead would be worth it.

I'll try out the other method you've described, and see what happens.

Regards,
-Bryan