Method of removing unneeded data from DB2 logs and other data sets having displacement-dependent data

• US 5,761,676 A
• Filed: 09/19/1994
• Issued: 06/02/1998
• Est. Priority Date: 09/19/1994
• Status: Expired due to Term

• Current Assignee: BMC Software Incorporated (KKR & Co., Inc.)
• Original Assignee: BMC Software Incorporated (KKR & Co., Inc.)
• Inventors: Todd, Jeffrey James, Wood, Gregory D.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Choules, Jack M.
• Application Number:
  US08/308,759
• Time in Patent Office: 1,352 Days
• Field of Search: 395/600, 395/622, 395/621, 395/620, 395/616, 395/618, 707/202
• US Class Current: 1/1
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

In a data set containing displacement-dependent data (e.g., data identified by relative byte address), such as a DB2 log data set, data that is determined to be unneeded or otherwise removable is overwritten with a compressible binary pattern such as a sequence of binary zeros. The resulting substitute data set can be compressed to occupy less storage space and require less time for data recovery.

Claims

1. A method of compressing DB2 log data set in a computer system, said DB2 log data set including data recovery data identified by its respective position within said log data set and having a data set name, comprising:

(a) copying data from said data set into temporary storage, referred to as a working copy;

(b) overwriting a portion of said working copy that is not needed for data recovery, referred to as removable data, with a sequence of binary zeros;

(c) writing data in said working copy in a loss-less, compressed form to a physical data set, referred to as a compressed data set;

(d) if all of said data recovery data has not been written to said compressed data set, then repeating steps (a) through (c); and

(e) uncataloging said DB2 log data set;

(f) renaming said compressed data set with said data set name; and

(g) deleting said DB2 log data set.

5. A computer programmed to execute the operations recited in a specified one of claims 1, 2, 3, and 4.

6. A machine-readable computer program storage device having encoded therein a program of instructions for performing the operations recited in a specified one of claims 1, 2, 3, and 4.

2. A method of compressing a DB2 log data set in a computer system, said DB2 log data set including data recovery data identified by its respective position within said log data set, comprising:

(a) copying data from said data set into temporary storage, referred to as a working copy;

(b) overwriting a portion of said working copy that is not needed for data recovery, referred to as removable data, with a compressible binary pattern;

(c) writing data in said working copy in a loss-less compressed form to a physical data set, referred to as a compressed data set;

(d) if all of said data recovery data has not been written to said compressed data set, then repeating steps (a) through (c); and

(e) substituting said compressed data set for said DB2 log data set.

3. The method of claim 2, wherein said compressible binary pattern is a sequence of binary zeros.

4. An improved method of storing data in a computer system in a data set in which data items in said data set are identified by their respective position within said data set, said method comprising:

(a) reading said data set into a buffer;

(b) overwriting a removable portion of data in said buffer, referred to as removable data, with a compressible binary pattern;

(c) writing the data in said buffer to a physical data set, referred, to as a substitute data set; and

(d) substituting said substitute data set for said data set;

wherein writing data in said buffer to a physical data set includes loss-less compression of said data.