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Database server system with improved methods for logging transactions

  • US 6,321,234 B1
  • Filed: 11/08/1996
  • Issued: 11/20/2001
  • Est. Priority Date: 09/18/1996
  • Status: Expired due to Term
First Claim
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1. In a database system for processing a sequence of database changes as a transaction, said database system capable of processing multiple transactions from concurrently connected clients, a method for posting changes occurring in the database system to a transaction log in a manner that reduces contention among transactions for the transaction log, the method comprising:

  • receiving multiple transactions, each transaction being received as a sequence of SQL commands from a given client requesting changes to a database;

    for each change to the database for a given transaction of a given client, creating a log record describing the change and storing the log record in a private log cache for that given transaction, said private log cache for storing log records which have been created for that given transaction but not yet posted to the transaction log, so that each transaction is associated with its own private log cache; and

    upon receiving from a particular client for a particular transaction one of the SQL commands which commits changes to the database, performing substeps of;

    (i) flushing the private log cache for that particular transaction to the transaction log, and (ii) flushing the transaction log to disk, wherein said log records are flushed to the transaction log before any corresponding data pages affected by said given task are flushed to disk;

    wherein at least one change includes a modification to a data page stored in memory and wherein said data page is pinned to said private log cache such that said data page can only be written to disk after its corresponding log records for the modification are flushed from the private log cache to the transaction log and then flushed from the transaction log to disk.

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