Independent distributed database system

• US 6,446,092 B1
• Filed: 03/15/1999
• Issued: 09/03/2002
• Est. Priority Date: 11/01/1996
• Status: Expired due to Term

• Current Assignee: Progress Software Corporation
• Original Assignee: PeerDirect Company
• Inventors: Sutter, Herbert P.
• Primary Examiner(s): Mizrahi, Diane D.
• Application Number:
  US09/270,199
• Time in Patent Office: 1,268 Days
• Field of Search: 707/9, 707/10, 707/200, 707/201, 707/202, 707/203, 712/29, 714/736, 709/248, 709/232
• US Class Current: 1/1
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: G06F 21/6227 where protection concerns the structure of data, e.g. records, types, queries
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

An independent distributed database system comprising a plurality of sites wherein all users at all sites work off-line with local data. All application transactions are against the local database only, and every site stores “all and only” the data it needs. On-line transactions occur only in the background, including a periodical “synch” between sites that transmits any changes to data of interest to that site. If the background operations are interrupted or the network is temporarily unavailable, the user does not see new changes made at other sites until the data link is available again, but is otherwise unaffected. It is a feature that no site acts as a “server” for any other site. Some sites may store more data or have more users than others, but all sites are logically peers.

Claims

1. A distributed relational database system for a computer network, said system comprising:

a plurality of sites;

each of said sites including processing means for storing and manipulating data independent of said other sites, and said data including a copy of data to be shared with said other sites;

said sites having means for connecting to said network and communicating with other sites connected to the network; and

said processing means including means for asynchronously propagating a copy of shared data stored locally by connecting to said network and transferring said shared data to other sites connected to the network so that said manipulated shared data is updated at said other sites.

2. The distributed relational database system as claimed in claim 1, wherein said database system comprises a plurality of activities and each of said activities comprises selected sites belonging to an activity group.

3. The distributed relational database system as claimed in claim 2, wherein said activity group is defined by said sites collaborating on an activity.

4. The distributed relational database system as claimed in claim 3, wherein each of said sites includes information pertaining to said activity, said information being stored locally at said site.

5. The distributed relational database system as claimed in claim 4, wherein said information stored locally at each of said sites belonging to said activity group together forms a database for said activity.

6. The distributed relational database system as claimed in claim 3, wherein information is stored in tables, and said tables comprise a plurality of columns and rows, and said tables are grouped into record fragments, each of said record fragments including one or more columns in a row.

7. The distributed relational database system as claimed in claim 6, wherein said fragments comprise fields and each of said fragments serves as a unit of replication.

8. The distributed relational database system as claimed in claim 7, wherein said fields have a common update responsibility.

9. The distributed relational database system as claimed in claim 6, further including means for securing an application for an activity group.

10. The distributed relational database system as claimed in claim 9, wherein said means for securing includes a hierarchal trust structure comprising a trusted root, an organization certification authority and an application certification authority, said trusted root having means for generating license certificates for said organization certification authority, and said organization certification authority having means for generating license certificates for said application certification authority, and said application certification authority having means for generating license certificates for sites and users belonging to said application network or activity group.

11. The distributed relational database system as claimed in claim 10, wherein said means for generating license certificates for said organization certification authority comprises a signing key.

12. The distributed relational database system as claimed in claim 10, wherein said means for generating license certificates for sites and users belonging to said application network comprises a signing key for user certificates and a signing key for command certificates.

13. The distributed relational database system as claimed in claim 10, wherein said means for generating license certificates for sites and users includes means for generating a site certificate for a new site added to said network.

14. The distributed relational database system as claimed in claim 13, wherein said means for generating a site certificate comprises an application-site certification signing key.

15. The distributed relational database system as claimed in claim 9, wherein said means for securing includes means for validating the integrity of a fragment.

16. The distributed relational database system as claimed in claim 15, further including means for replacing an invalid fragment at one site with a valid version of said fragment replicated from another site.

17. The distributed relational database system as claimed in claim 15, wherein said means for validating a fragment comprises an encrypted field, and said site having means for generating said encrypted field, and said encrypted field being generated at the site at which the fragment was last changed.

18. The distributed relational database system as claimed in claim 17, wherein said encrypted field is derived from a fragHash value for said fragment.

19. The distributed relational database system as claimed in claim 9, wherein said means for securing includes means for encrypting a field in a record.

20. The distributed relational database system as claimed in claim 19, wherein said encrypted field is derived from a uniqueHash value for the field in said record.

21. The distributed relational database system as claimed in claim 9, wherein said means for securing includes means for securing a local database.

22. The distributed relational database system as claimed in claim 21, wherein said means for securing the local database comprises design-time security tables.

23. The distributed relational database system as claimed in claim 21, wherein said means for securing the local database comprises run-time permissions tables.

24. The distributed relational database system as claimed in claim 23, including means for applying permissions defined in said run-time permissions tables in groups to selected users or sites.

25. The distributed relational database system as claimed in claim 21, further including means for determining a minimal set of cryptographic security keys for a selected user to work with said application.

26. The distributed relational database system as claimed in claim 6, further including means for creating distributed records for said fragments and providing each of said distribution records with a unique identity.

27. The distributed relational database system as claimed in claim 26, wherein said unique identity comprises a unique record identifier and a fragment number denoting the columns of the records that the fragment represents.

28. The distributed relational database system as claimed in claim 27, wherein said means for creating distributed records includes means for allocating said unique identifiers.

29. The distributed relational database system as claimed in claim 2, wherein an activity comprises a root record and a plurality of records directly or indirectly related to said root record, and said activity defines a shareable subset of data in the database system.

30. The distributed relational database system as claimed in claim 29, wherein said activity includes an activity part comprising a selected table.

31. The distributed relational database system as claimed in claim 30, wherein said activity part comprises a subset of columns belonging to one or more of said tables.

32. The distributed relational database system as claimed in claim 2, wherein said sites comprise spine sites and non-spine sites, said spine sites exhibiting high availability to the network, and said non-spine sites exhibiting low availability to the network.

33. The distributed relational database system as claimed in claim 32, further including means for selectively mapping said spine sites.

34. The distributed relational database system as claimed in claim 33, wherein said means for selectively mapping said spine sites comprises a spanning tree having nodes corresponding to said spine sites.

35. The distributed relational database system as claimed in claim 34, further including means for reconfiguring said spanning tree, said means for reconfiguring being responsive to a node becoming unavailable to said network.

36. The distributed relational database system as claimed in claim 35, wherein said spanning tree comprises a balanced tree having a minimum height and said nodes being weighted according to bandwidth and availability.

37. The distributed relational database system as claimed in claim 34, further including means for removing a spine site from said spanning tree in response to a site leaving said activity group.

38. The distributed relational database system as claimed in claim 32, further including means for selectively mapping said non-spine sites to said spine sites.

39. The distributed relational database system as claimed in claim 2, wherein information is stored in tables, and said tables comprise columns and rows, and said tables are grouped into record fragments, each of said record fragments including one or more columns in a row.

40. The distributed relational database system as claimed in claim 39, wherein said processing means includes a local clock and means for generating time-stamps for each of said fragments stored locally at said site, and said time-stamp providing an age for the corresponding fragment.

41. The distributed relational database system as claimed in claim 40, wherein said fragments stored at said sites collectively form a database for said activity.

42. The distributed relational database system as claimed in claim 41, wherein an activity comprises a root record and a plurality of records related to said root record.

43. The distributed relational database system as claimed in claim 41, wherein said means for propagating comprises replication means for replicating selected fragments at other sites, and said selected fragments comprising most recent fragments as determined from said time-stamps.

44. The distributed relational database system as claimed in claim 43, wherein said replication operation comprises a background data synchronization operation between sites connected to said network.

45. The distributed relational database system as claimed in claim 43, wherein said time-stamp comprises a date and time field, and said date and time field is relative to said local clock at said site where said information unit is stored.

46. The distributed relational database system as claimed in claim 40, wherein said sites comprise spine sites and non-spine sites, said spine sites exhibiting high availability to the network, and said non-spine sites exhibiting low availability to the network.

47. The distributed relational database system as claimed in claim 46, further including replicator means for replicating changes to selected fragments between said spine and non-spine sites, said replicator means comprising means at each non-spine site for transmitting selected fragments to one of said spine sites, and said spine sites having means for sharing said selected fragments, and said spine sites including means for forwarding said shared fragments to other non-spine sites which link with said spine sites.

48. The distributed relational database system as claimed in claim 47, wherein said selected fragments comprise fragments having the most recent changes as determined from said time-stamps.

49. The distributed relational database system as claimed in claim 40, further including compensating means for compensating drift in the local clocks for said sites in said network.

50. The distributed relational database system as claimed in claim 49, wherein said clock drift compensating means comprises means for storing a past time difference between the clock at said site and the clocks of other sites, and means for comparing said past time difference to a current time difference and using said comparison for compensating said clock drift.

51. The distributed relational database system as claimed in claim 40, further including means for generating a reference time between sites on said network.

52. The distributed relational database system as claimed in claim 51, wherein said means for generating a reference time comprises means for sending a message from an initiator site to a sending site at a start time, and means for determining an arrival time when a reply message is received at said initiator site, and means for determining a reference time for said initiator site by calculating the midpoint for the interval from said start and arrival times.

53. The distributed relational database system as claimed in claim 40, further including means for checking clocks of said sites comprising means for comparing clock readings at said sites with clock readings taken from a designated time keeping site.

54. The distributed relational database system as claimed in claim 1, wherein said processing means includes a local clock and means for generating time-stamps for units of said information stored locally at said site, and said time-stamp providing an age for said information unit.

55. The distributed relational database system as claimed in claim 1, further including means for specifying transactions to be utilized when applying changes at the destination site during the asynchronous propagation of updates to shared data from one of said sites to a destination site.

56. The distributed relational database system as claimed in claim 55, wherein said means for specifying transactions comprises means for defining a group of one or more tables so that all the propagated updates to said group of tables are applied at said destination site in one transaction.

57. The distributed relational database system as claimed in claim 55, wherein said means for specifying transactions comprises means for defining a set of related records organized as a tree, wherein said set includes a base record and a plurality of records directly or indirectly related to said base record so that all the propagated updates to said set of records are applied at said destination site in one transaction.