Re: [Sqlrelay-discussion] Manifold FreeTDS symptoms

[David M. <dav...@fi...>]

The only introspection that's available in SQL Relay is to turn on 
server-side debugging and dig through the logs.  There's no dashboard or 
anything like that.  I'm not sure how useful it would be if there was, 
queries would go flying by too quickly to make sense of them.  There is 
a stats monitor that shows how many connections and cursors and such are 
open, but there's a bug in it now and it's not reliable.

Freetds only supports 1 cursor per database connection, but Zope and 
other frameworks use multiple cursors to handle nested queries.  SQL 
Relay provides a multi-cursor interface to Zope by caching result sets 
and sharing the one freetds cursor across multiple sqlrelay cursors.  
The setResultSetBufferSize() option can kink this up though, and cause 
this error.  Is it possible that somebody modified your copy of the Zope 
API, or the Python API that it relies on to use setResultSetBufferSize()?

If so, I'd expect you'd see problems when running nested queries and an 
outer query returns more rows than setResultSetBufferSize() is set to 
accommodate.

Also, what version of freetds are you using?

A quick, reliable solution would be to build SQL Relay against sybase 
client libs rather than freetds and use that.  It supports multiple 
cursors per connection.  But, there could certainly be licensing issues 
there.

Dave
dm...@4a...

On 01/26/2010 05:56 PM, Cameron Laird wrote:
> I'm in the middle of a collection of people pointing fingers at each 
> other, and looking for a shortcut to some saner place.  Help would be 
> welcome.
>
> Our 0.38-based (is there a canonical way to tell version?  
> /usr/bin/sqlrclient-config mentions "version=0.38") SQL Relay is 
> connected to a Sybase instance.  One of our developers is reporting 
> all sorts of errors in a Zope application, including frequent but 
> poorly-reproducible "No server-side cursors were available ..." and 
> "Attempt to initiate a new SQL Server operation with results 
> pending".  As I read the FAQ, 0.37 should have eliminated the latter, 
> and the former makes no sense to me, as the application is a 
> Zope-based one, and therefore should use only a single connection, right?
>
> What introspection does SQL Relay offer?  Is there a practical way to 
> ask it which cursors and threads are running, and what they're 
> currently doing?  Is there any reason to think an update of SQL Relay 
> itself will help?  I'm open to suggestion on where to start with this 
> tangle.
>
>
>
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