[Zope] Looking if a record with a given key exists in a database several times, in dtml

Hi all! I have a problem: in dtml, I have to iterate through a very big list and for each item I must look if there is a record with that key in a database. I can't run a 'select' ZSQLMethod for each, because it would take too long. What I want to do is run the 'select' ZSQLMethod once and load the results in a variable (an array or dictionary) which then will be faster to look up in, or look up in the results of that query in some fast way. I have searched zope.org, but found nothing. Any ideas? Igor Leturia