A method for updating a data object stored in a data repository, the data object corresponding to an instance of a document relating to an electronic document or file having an object type and having one or more traits, at least one of said one or more traits used to define a data structure for the data object, the method comprising: receiving an upgrade to one or more traits associated with a definition of the object type, wherein a first trait instance of a first trait of the one or more traits is related to a characteristic of a first instance of the data object, and a second trait instance of the first trait is related to a characteristic of a second instance of the data object; storing the upgrade to the one or more traits; and in response to an access of the first trait instance: determining the version number associated with the one or more traits corresponding to the accessed first trait instance; determining, based at least in part on the version number associated with the first trait, that update to the first trait includes a more recent version of the data structure defined by the first trait; and in response to a determination that the update to the first trait includes a more recent version of the data structure defined by the first trait, modifying the data structure corresponding to the first trait instance but not a data structure corresponding to the second trait instance, the data structure corresponding to the first trait instance being modified based at least in part on the update to the upgrade, wherein modifying the data structure corresponding to the first trait instance includes modifying at least one change to a number of data fields, or to a type or other attribute of a data field included in the first trait instance. receiving an upgrade to one or more traits associated with a definition of the object type, wherein a first trait instance of a first trait of the one or more traits is related to a characteristic of a first instance of the data object, and a second trait instance of the first trait is related to a characteristic of a second instance of the data object; storing the upgrade to the one or more traits; and in response to an access of the first trait instance: determining the version number associated with the one or more traits corresponding to the accessed first trait instance; determining, based at least in part on the version number associated with the first trait, that update to the first trait includes a more recent version of the data structure defined by the first trait; and in response to a determination that the update to the first trait includes a more recent version of the data structure defined by the first trait, modifying the data structure corresponding to the first trait instance but not a data structure corresponding to the second trait instance, the data structure corresponding to the first trait instance being modified based at least in part on the update to the upgrade, wherein modifying the data structure corresponding to the first trait instance includes modifying at least one change to a number of data fields, or to a type or other attribute of a data field included in the first trait instance. determining the version number associated with the one or more traits corresponding to the accessed first trait instance; determining, based at least in part on the version number associated with the first trait, that update to the first trait includes a more recent version of the data structure defined by the first trait; and in response to a determination that the update to the first trait includes a more recent version of the data structure defined by the first trait, modifying the data structure corresponding to the first trait instance but not a data structure corresponding to the second trait instance, the data structure corresponding to the first trait instance being modified based at least in part on the update to the upgrade, wherein modifying the data structure corresponding to the first trait instance includes modifying at least one change to a number of data fields, or to a type or other attribute of a data field included in the first trait instance.