if (getTransactionRule() == TransactionRule.COMMIT_AT_END) {
txn = targetDb.startTransaction();
}
for (Document source : coll) {
if (getTransactionRule() == TransactionRule.COMMIT_EVERY_SOURCE) {
txn = targetDb.startTransaction();
}
DateTime sourceLastMod = source.getLastModified();
// Object lookupKey = Factory.wrappedEvaluate(session, getSourceKeyFormula(), source);
Object lookupKey = getSourceKeyFormula().getValue(source);
DocumentCollection targetColl = targetView.getAllDocumentsByKey(lookupKey, true);