Highly reliable online system

  • US 5,596,706 A
  • Filed: 08/10/1994
  • Issued: 01/21/1997
  • Est. Priority Date: 02/28/1990
  • Status: Expired due to Term
First Claim
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1. A database synchronization control system comprising:

  • a main computer system for accessing ones of a plurality of related first records in a main database based on transactions inputted from terminals wherein said accessing includes updating said ones of a plurality of related first records, and delivering main database update information relating to the updating performed on said main database; and

    ,a sub-computer system coupled with said main computer system for receiving the update information and updating ones of a plurality of related second records in a sub-database corresponding to said main database, the updating being executed on the basis of said update information, wherein;

    said terminals include means for storing and transmitting both i) transaction sequence numbers counted up each time a transaction is generated and ii) transaction data to said main computer system;

    said main computer system includes means for transmitting the main database update information and the transaction sequence number of each of said terminals to said sub-computer system; and

    ,means in each of said-terminals operative when said main computer system is changed over to said sub-computer system, for receiving a latest transaction sequence number of a transaction which has been reflected to the sub-database from said sub-computer system, comparing the received transaction sequence number with the latest transaction sequence number transmitted to said main computer system and stored therein and automatically retransmitting a number of transactions, said number matching the difference between the received transaction sequence number and the latest transaction sequence number stored in the terminal, whereby contents of said main database and said sub-database are synchronized with each other.

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