Re: Shared memory

[Thomas Hallgren <thomas(at)tada(dot)se>]

Tom Lane wrote:
> Thomas Hallgren <thomas(at)tada(dot)se> writes:
>   
> > This FENCED/NOT FENCED terminology would be a good way to
> > differentiate between the two approaches. Any chance of that syntax
> > making it into the PostgreSQL grammar, should the need arise?
> >     
>
> Of what value would it be to have it in the grammar?  The behavior would
> be entirely internal to any particular PL in any case.
>
>   
Not necessarily but perhaps the term FENCED is incorrect for the concept 
that I have in mind.

All languages that are implemented using a VM could benefit from the 
same remote UDF protocol. Java, C#, perhaps even Perl or Ruby. The flag 
that I'd like to have would control 'in-process' versus 'remote'.

I'm not too keen on the term FENCED, since it, in the PL/Java case will 
lead to poorer isolation. Multiple threads running in the same JVM will 
be able to share data and a JVM crash will affect all connected sessions.

Then again, perhaps it's a bad idea to have this in the function 
declaration in the first place. A custom GUC parameter might be a better 
choice. It will not be possible to have some functions use the 
in-process approach and others to execute remotely but I doubt that will 
matter that much.

I'm still eager to hear what it is in the current PL/Java that you 
consider fundamental unresolvable problems.

Regards,
Thomas Hallgren