How do you create the database connection in your code? Note that when using the Database Toolbox with "parfor", you need to create the database connection on each worker, not just on the client. You should include the database connection statement inside of the "parfor" loop. Since a particular worker may execute multiple iterations of the "parfor", however, you should be sure to create the connection only once per worker. You can do this by creating a "persistent" variable. For example:
parpool
parfor i=1:N
output{i} = myFun(i)
end
where "myFun" is defined as:
function y = myFun(i)
persistent conn
if isempty(conn)
conn = database(...)
end
curs = exec(conn, 'SELECT * FROM myTable'); % This on the workers
curs = fetch(curs);
y = curs.Data;
...
end
On each individual worker, the value of the persistent variable "conn" is retained in memory between calls to "myFun".
Also, are you using a JDBC or ODBC driver? When working with JDBC drivers, you need to make sure that the JDBC driver is actually loaded on all workers, so you may also need to use something like:
pctRunOnAll('javaaddpath(''yourdriver.jar'')')
after having opened the "parpool".
