Many possibilities out there, but what I would do is create a range.
So I would add another field in master table, say ValidToDate and initialize it to 12/31/2999. Then I would do intervalmatch() function passing Key as parameter. Something link this
Master:
Key, ValidFrom, surcharge
Transaction:
Key, Date
Left join (Master) LOAD Key, date(12/31/2999) as ValidTo Resident Master;
Intervalmatch(Date, Key)
LOAD ValidFrom, ValidTo, Key Resident Master;
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And if you do not like synthetic keys, you can left join master table contents back to transactions by using left join. Like:
Master:
Key, ValidFrom, surcharge
Transaction:
Key, Date
Left join (Master) LOAD Key, date(12/31/2999) as ValidTo Resident Master;
Left join (Transaction)
Intervalmatch(Date, Key)
LOAD ValidFrom, ValidTo, Key Resident Master;
Left join (Transaction)
LOAD * RESIDENT Master;
DROP Table Master.
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Hope this gives you some ideas & helps you a little.
