Loop over attribute values for executing SQL in Nifi - apache-nifi

Question

I would like to know how may I accomplish the following use case in Nifi Flow:
I would like to execute SQL query for date range over a loop. The date range are provided from list of attribute values.
For example: If my list of attributes are : 2013-01-01 2013-02-01 2013-03-01, I would like to execute SQL operation over a loop such that:
select * from where startdate>=2013-01-01 and enddate<2013-02-01
followed by:
select * from where startdate>=2013-02-01 and enddate<2013-03-01
Therefore, for the same, I roughly know the idea but cant implement concretely:
UpdateAttribute (containing list of date values) -> SplitText-> RouteOnAttribute -> ExecuteSQL
Thanks

Answer 1

In NiFi 1.8.0, you can use DuplicateFlowFile for this (via NIFI-5454). You can start with UpdateAttribute to add the count of delineated values in your list (let's assume it is an attribute called datelist), perhaps set list.count to
${allDelineatedValues(${datelist}, " "):count()}
Then in DuplicateFlowFile you can set Number of Copies to ${list.count:minus(1)}. Each flow file downstream will have a copy.index attribute set (the original having index 0), so you can use that in ReplaceText in conjunction with getDelimitedValue(), perhaps setting the content to the following:
select * from myTable where
startdate >= ${datelist:getDelimitedField(${copy.index:plus(1)})} and
enddate < ${datelist:getDelimitedField(${copy.index:plus(2)})}