parfeval with fetch not working

Hello guys. When I call the fetch() function with parfeval, I get the following error:

parfeval(@fetch,1,database,query)

Error: 'Dot indexing is not supported for variables of this type.'

On the other hand, without parfeval, the function works perfectly. What could it be?

Answer 1

[Edric Ellis]

You cannot pass database connection objects to workers directly like this. You should use createConnectionForPool . There are examples on that doc page that show you how to set up and use this. You'll end up with something like this:

c = createConnectionForPool(..);
% Wrap the call to "fetch" to unpick the .Value out of the pool connection
% object 'c'.
fut = parfeval(@(c, varargin) fetch(c.Value, varargin{:}), 1, c, query)

[HILTON MARQUES SANTANA]

Thanks! It's working. Just another question. I am trying to speed up some queries on a online database on this way:

f = parfeval(@(c, varargin) fetch(c.Value, varargin{:}), 1, c, query1);

f(end+1) = parfeval(@(c, varargin) fetch(c.Value, varargin{:}), 1, c, query2);

f(end+1) = parfeval(@(c, varargin) fetch(c.Value, varargin{:}), 1, c, query3);

res1 = fetchOutputs(f(1));

res2 = fetchOutputs(f(3));

res3 = fetchOutputs(f(2));

But the time is not decreasing too much. There is a more efficient approach?

Thanks in advance