How are unused SOLIDWORKS PDM Serial Numbers handled?
Article by Joe Medeiros, CSWE updated December 14, 2020
Article
While helping a customer with an issue they were having with their SOLIDWORKS PDM serial numbers, I came across an article on how unused serial numbers are handled. This article really helped me understand the way serial numbers are doled out and I believe others will find this information useful.
In this article, I have summarized that information. I would encourage you to read the full article which is available from the SOLIDWORKS Knowledgebase.
As those who have implemented and/or administered SOLIDWORKS PDM Professional likely know, PDM Professional includes a serial number generator.

PDM Serial Numbers
A serial number is a counter that will increment by one, each time it is used. Serial numbers are assigned to file by means such as:
- The SOLIDWORKS add-in, if the option is enabled
- A control in a data card
- Through the use of a PDM template
- An option in Copy-Tree
- Through a call in an API (application programming interface)
Regardless of how the serial number gets pulled, that serial number will be reserved in the SQL database. For the most part, this shouldn’t cause issues, but this can occasionally result in behavior that can cause confusion.
A case study created by SOLIDWORKS Support to illustrate this behavior uses as an example of a PDM template that generates a serial number.

Serial Numbers in a PDM Template
When a user runs the PDM template, the template generates a serial number (DRW-100) and this serial number is reserved. While this user continues to work in a template, another user creates a couple of new components through the Template. These components get assigned the next available serial numbers, which are DRW-101 and DRW-102. The first user then decides to cancel the template creation. Even though no file was created the serial number DRW-100 is still reserved in the database. If the second user were to then create a third component, that component would get the reserved serial number (DRW-100), not DRW-103. This will continue as long as there are reserved serial numbers. When all reserved serial numbers are used, the next counter value will be used.

Next Counter Value
Because these reserved values are lower than the values previously generated by the second user, that user may mistakenly believe that serial numbers are not being generated incorrectly.
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