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I received a geodatabase from a contractor and I observed there are multiple feature classes with column of Global ID type.

These Global ID type columns, when I checked data i realized there are multiple records with in same feature class having duplicate global ids.

This seems to be against global id column integrity so does this mean this record was generated outside Esri environment?

Can I replace duplicate global ids with new global ids ?

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    Generally, copying a feature class with a GlobalID field results in a new ID value, which is often a problem, so some tools allow you to override and preserve the value. This makes little sense in your context, but it's still possible to use Esri tools to corrupt a data delivery in this fashion. Recalculating values is possible, but may corrupt foreign key references.
    – Vince
    Dec 1, 2019 at 12:41
  • Thank you. So it means that if contractor copied feature class from some other gdb but using external tool to preserve global id that has caused the duplication? Dec 2, 2019 at 4:17
  • External or internal; no way to tell from here.
    – Vince
    Dec 2, 2019 at 4:20
  • okay so if we have such a feature class in which features have global ids (preserved from some process) and if we add a new feature that might get an existing global id? My understanding was ESRI on the backend was generating new global ids based on the combination of timestamp, geodatabase name, feature class name etc. so in this way since using timestamp it should not return a duplicate. Dec 2, 2019 at 4:50
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    My understanding is that GlobalID is just a special case of the UUID column type, in which uniqueness is enforced (primary key, not foreign key). The UUID generator cannot produce duplicates (collisions), so adding in names could only increase the likelihood of collision. The main problem with UUID types is that their randomization makes them very inefficient index keys (highly fragmented). Using a single UUID generator should eliminate any chance of duplication; therefore your duplicates are processing errors.
    – Vince
    Dec 2, 2019 at 11:48

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