[Zope] view rendered zsql query without execution?

Hi, as the rendered zsql query source is the key for the cached results, it should be possible to view the source even if the query is failing due to db-problems. Has anybody done the trick yet or can give a hint how to do it? -- Thanks, Elena PS.: I know the one with <dtml-var "myZsqlMethod(REQUEST, src__=1)"> but this requires an errorfree execution of the method.