Data processing system using substantially unique identifiers to identify data items, whereby identical data items have the same identifiers
DC CAFCFirst Claim
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1. In a data processing system, an apparatus comprising:
- identity means for determining, for any of a plurality of data items present in the system, a substantially unique identifier, the identifier being determined using and depending on all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and
existence means for determining whether a particular data item is present in the system, by examining the identifiers of the plurality of data items.
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Abstract
In a data processing system, a mechanism identifies data items by substantially unique identifiers which depend on all of the data in the data items and only on the data in the data items. The system also determines whether a particular data item is present in the database by examining the identifiers of the plurality of data items.
619 Citations
48 Claims
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1. In a data processing system, an apparatus comprising:
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identity means for determining, for any of a plurality of data items present in the system, a substantially unique identifier, the identifier being determined using and depending on all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and existence means for determining whether a particular data item is present in the system, by examining the identifiers of the plurality of data items. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method of identifying a data item present in a data processing system for subsequent access to the data item, the method comprising:
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determining a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and accessing a data item in the system using the identifier of the data item. - View Dependent Claims (31, 32, 41, 42, 43, 44, 45, 48)
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33. A method for duplicating a given data item present at a source location to a destination location in a data processing system, the method comprising:
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determining a substantially unique identifier for the given data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; determining, using the data identifier, whether the data item is present at the destination location; and based on the determining whether the data item is present, providing the destination location with the data item only if the data item is not present at the destination. - View Dependent Claims (34)
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35. A method for determining whether a particular data item is present in a data processing system, the method comprising:
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(A) for each data item of a plurality of data items present in the system, (i) determining a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and (ii) making and maintaining a set of identifiers of the plurality of data items; and (B) for the particular data item, (i) determining a particular substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and (ii) determining whether the particular identifier is in the set of data items.
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36. A method of backing up, of a plurality of data items present in a data processing system, data items modified since a previous backup time in the data processing system, the method comprising:
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(A) maintaining a backup record of identifiers of data items backed up at the previous backup time; and (B) for each of the plurality of data items present in the data processing system, (i) determining a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; (ii) determining those data items of the plurality of data items whose identifiers are not in the backup record; and (iii) based on the determining, copying only those data items whose data identities are not recorded in the backup record. - View Dependent Claims (37)
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38. A method of locating a particular data item at a location in a data processing system, the method comprising:
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(A) determining a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; (B) requesting the particular data item by sending the data identifier of the data item from the requester location to at least one location of a plurality of provider locations in the system; and (C) on at least some of the provider locations, (a) for each data item of a plurality of data items at the provider locations, (i) determining a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only on the data in the data item, whereby two identical data items in the system will have the same identifier; and (ii) making and maintaining a set of identifiers of data items, (b) determining, based on the set of identifiers, whether the data item corresponding to the requested data identifier is present at the provider location; and (c) based on the determining, when the provider location determines that the particular data item is present at the provider location, notifying the requestor that the provider has a copy of the given data item. - View Dependent Claims (39)
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40. A method of locating a particular data item among a plurality of locations, each of the locations having a plurality of data items, the method comprising:
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determining, for the particular data item and for each data item of the plurality of data items, a substantially unique identifier for the data item, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier; and determining the presence of the particular data item in each of the plurality of locations by determining whether the identifier of the particular data item is present at each of the locations.
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46. A method of maintaining at least a predetermined number of copies of a given data item in a data processing system, at different locations in the data processing system, the data processing system being one wherein data is identified by a substantially unique identifier, the identifier depending on and being determined using all of the data in the data item and only the data in the data item, whereby two identical data items in the system will have the same identifier, and wherein any data item in the system may be accessed using only the identifier of the data item, the method comprising:
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(i) sending, from a first location in the system, the data identifier of the given data item to other locations in the system; and (ii) in response to the sending, at each of the other locations, (A) determining whether the data item corresponding to the data identifier is present at the other location, and based on the determining, and (B) informing the first location whether the data item is present at the other location; and (iii) in response to the informing from the other locations, at the first location, (A) determining whether the data item is present in at least the predetermined number of other locations, and based on the determining, (B) when less than the predetermined number of other locations have a copy of the data item, requesting some locations that do not have a copy of the data item make a copy of the data item. - View Dependent Claims (47)
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Specification