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OCLC Support

Is there a difference between DDA and PDA records? Why are there so many deliveries of the same record?

Applies to
  • WorldShare Collection Manager
    • WorldCat knowledge base

There isn't any difference between the two records that get delivered if a title moves from a DDA collection to a Purchased collection when both collections are configured to output into a separate file.   If the number of files to process is too high, we recommend having DDA and Purchased collections output into a single separate file, e.g. “JSTOR” instead of “JSTORDDA” and “JSTORPurchased.”  Then when a title gets moved from DDA to Purchased, you will only receive one record for that title.  You can also set your delivery frequency to coincide with the frequency we receive data from the provider.  An example would be for JSTOR which is weekly.  This may reduce the amount of work required on your part when you load record files.  For assistance with these settings or for help with additional questions, contact OCLC Support

 Delivery frequencies

If you experience delivery frequency discrepancies, what may have happened is that if a title is held in multiple collections configured with different delivery frequencies and set to output into separate files, if a record in the collection with the shortest delivery frequency is modified, an update will be delivered for all the collections that hold that title.  So for example, if your JSTOR DDA is using the institution-level setting (weekly), but the Purchased collection is configured for daily delivery and the title, China’s dilemma, is held within both the DDA and the Purchased collection, although they have different OCNs, the OCN 430819042 is listed in the group OCN for the DDA collection, so when the record is delivered daily in a file labeled “ JSTORPurchased" as subsequent delivery, it is also being delivered in “JSTOR” on a daily delivery frequency even though the collection is set to deliver records on a weekly basis (Note:  If you receive a file for a collection and it has the wrong delivery frequency in the file name, then that record is likely being output for a different collection with the specified delivery frequency, but because the title is held in multiple collections, the record is being output into separate files for all collections that hold that particular title. Detail about the meaning of the file names is accessible in Additional Information below.

Additional information
  • What is DDA?: Demand Driven Acquisition (DDA, also called Patron Driven Acquisition or PDA) lets your patrons drive which items you purchase. With your vendor, you set up a collection of titles available for DDA, and then a purchase is triggered when a patron accesses an item via your Discovery.
  • What does the file name mean
  • About DDA collections
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