title: Creating a global variable in Talend to use as a filter in another component
body: <p>I have job in Talend that is designed to bring together some data from different databases: one is a MySQL database and the other a MSSQL database. </p>
  
  <p>What I want to do is match a selection of loan numbers from the MySQL database (about 82,000 loan numbers) to the corresponding information we have housed in the MSSQL database.</p>
  
  <p>However, the tables in MSSQL to which I am joining the data from MySQL are much larger (~ 2 million rows), are quite wide, and thus cost much more time to query. Ideally I could perform an inner join between the two tables based on the loan number, but since they are in different databases this is not possible. The inner join that is performed inside a tMap occurs after the Lookup input has already returned its data set, which is quite large (especially since this particular MSSQL query will execute a user-defined function for each loan number).</p>
  
  <p>Is there any way to create a global variable out of the output from the MySQL query (namely, the loan numbers selected by the MySQL query) and use that global variable as an IN clause in the MSSQL query?</p>