Interaction between application of a log and maintenance of a table that maps record identifiers during online reorganization of a database

• US 5,721,915 A
• Filed: 06/01/1995
• Issued: 02/24/1998
• Est. Priority Date: 12/30/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Beavin, Thomas Abel, Sockut, Gary Howard
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): LEWIS, CHERYL RENEA
• Application Number:
  US08/457,150
• Time in Patent Office: 999 Days
• Field of Search: 364/413.01, 395/616, 395/617, 395/618, 395/202, 395/600
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2282 Tablespace storage structures; Management thereof
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

The present invention includes reorganization of a Database Management System (DBMS) The reorganization of the present invention is implemented by recording a first current Relative Byte Address (RBA) Then, data is copied from the old area in the table space to a new area in the table space in reorganized form. In the present invention, throughout most of reorganization a user maintains access to the DBMS'"'"'s normal facilities to read and write to the old area. The DBMS uses its normal facilities to record writing, which occurs during reorganization, in,a log. The reorganization in accordance with the present invention reads the log (that has been written to during reorganization) and processes the log to the new area to bring the new area up to date. This process is performed with the use of a RID mapping table. Finally, at the end of reorganization, the user'"'"'s access is switched from the old area to the new area.

Claims

1. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for performing reorganization in a database management system (DBMS), said method steps comprising:

reorganizing a data record in an old area of a table space, wherein said data record has an old record identifier (RID), while read/write access to said old area is retained;

directing said reorganized version of said data record to a new area in said table space, wherein said reorganized version of said data record has a new RID, while read/write access to said old area is retained;

maintaining a mapping table that maps between said old RID and said new RID;

copying a subset of a log;

translating a log entry RID for a log entry to said new RID, wherein said log entry RID is said old RID; and

applying said translated log entry with said new RID to said reorganized version of said data record in said new area in said table space.

2. The program storage device according to claim 1, wherein said steps of reorganizing and directing comprise the steps of:

unloading said data record from said old area;

reorganizing said data record;

reloading said reorganized version of said data record, except said old RID, in said new area; and

inserting an entry containing said old RID and said new RID into said mapping table during said reloading step.

3. The program storage device according to claim 1, wherein when said log entry comprises a plurality of log entries, and said method further comprises the steps of:

sorting said log entries by said old RIDs, prior to said step of translating; and

sorting said log entries by said new RIDs, after said step of translating and prior to said step of applying.

4. The program storage device according to claim 1, wherein said step of translating comprises the step of:

calculating an estimated new RID.

5. The program storage device according to claim 1, wherein said step of maintaining a mapping table comprises the steps of:

updating said mapping table for each said log entry to reflect a state of said reorganized version of said data record, prior to said step of applying said log entry; and

updating said mapping table for each said log entry to reflect a type of said log entry.

6. The program storage device according to claim 1, wherein said step of applying said log entry comprises:

updating a relative byte address (RBA) column in said mapping table for said reorganized version of said data record.

7. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for reorganizing a database, said method steps comprising:

recording a first current relative byte address (RBA) for a log as a first variable, while read/write access to an old area of a table space is retained;

performing reorganization of a data record with an old record identifier (RID) in said old area of said table space such that a reorganized version of said data record has a new RID in a new area of said table space, while read/write access to said old area is retained;

storing a second current RBA for said log as a second variable;

reading said first variable;

reading said second variable;

applying a first log entry including a log entry RID, wherein said log entry RID is said old RID, to said reorganized version of said data record identified by said new RID in said new area by using a RID mapping table to translate said old RID to said new RID, while read\write access to said old area is retained;

recording a third current RBA for said log as a third variable;

comparing a next iteration, which is a difference between said third variable and said second variable, with a most recent iteration, which is a difference between said second variable and said first variable;

implementing an action to allow said reorganization to catch up if said next iteration is at least as much as said most recent iteration;

quiescing write access to said old area, while said second variable is set to said third variable;

applying a second log entry with a second log entry RID, wherein said second log entry RID is said old RID, to said reorganized version of said data record identified by said new RID, by using said RID mapping table to translate said old RID to said new RID, while read-only access is retained;

quiescing all access of said table space;

converting access from said old area to said new area;

creating a backup copy of said table space containing said new area;

starting read/write access to said table space containing said new area; and

erasing said old area and said RID mapping table.

8. The program storage device according to claim 7, wherein said step of performing reorganization comprises the steps of:

unloading said data record from said old area;

reorganizing said data record;

reloading said reorganized version of data record, except said old RID, in said new area of said table space; and

inserting an entry containing said old RID and said new RID into said mapping table during said reloading step.

9. The program storage device according to claim 7, wherein said first and second log entry each comprise a plurality of log entries, and prior to said steps of applying said first and second log entries, further performing the steps of:

sorting pointers to said first and second log entries by said old RIDs;

copying a subset of said first and second log entries;

translating said old RID of each of said first and second log entries to said new RID; and

sorting pointers to said translated first and second log entries by said new RIDs.

10. The program storage device according to claim 9, wherein said step of translating by maintaining said mapping table further comprises the steps of:

updating said mapping table for each of said first and second log entries to reflect a state of said reorganized version of said data record; and

updating said mapping table for each of said first and second log entries to reflect a type of said log entry.

11. The program storage device according to claim 9, wherein said step of translating by maintaining said mapping table further comprises the step of:

updating a RBA column in said mapping table for said reorganized version of said data record.

12. A computer program product, comprising:

a computer usable medium having a computer readable program code means embodied in said medium for causing a database management system (DBMS) to be reorganized, the computer readable program code means comprising,

computer readable program code means for causing a computer to reorganize a data record in an old area of a table space, wherein said data record has an old record identifier (RID), while read/write access to said old area is retained;

computer readable program code means for causing a computer to direct said reorganized version of said data record to a new area in said table space, wherein said reorganized version of said data record has a new RID, while read/write access to said old area is retained;

computer readable program code means for causing a computer to maintain a mapping table that maps between said old RID and said new RID;

computer readable program code means for causing a computer to copy a subset of a log;

computer readable program code means for causing a computer to translate a log entry RID for a log entry to said new RID, wherein said log entry RID is said old RID; and

computer readable program code means for causing a computer to apply said translated log entry with said new RID to said reorganized version of said data record in said new area in said table space.

13. The computer program product according to claim 12, wherein said computer readable program code means for causing a computer to reorganize and direct comprises,

computer readable program code means for causing a computer to unload said data record from said old area;

computer readable program code means for causing a computer to reorganize said data record;

computer readable program code means for causing a computer to reload said reorganized version of said data record, except said old RID, in said new area; and

computer readable program code means for causing a computer to insert an entry containing said old RID and said new RID into said mapping table during said reloading step.

14. The computer program product according to claim 12, wherein when said log entry comprises a plurality of log entries, and said computer program product further comprises:

computer readable program code means for causing a computer to sort said log entries by said old RIDs, prior to said step of translating; and

computer readable program code means for causing a computer to sort said log entries by said new RIDs, after said step of translating and prior to said step of applying.

15. The computer program product according to claim 14, wherein said computer readable program code means for causing a computer to translate comprises:

computer readable program code means for causing a computer to calculate an estimated new RID.

16. The computer program product according to claim 12, wherein said computer readable program code means for causing a computer to maintain a mapping table comprises,

computer readable program code means for causing a computer to update said mapping table for each said log entry to reflect a state of said reorganized version of said data record, prior to said step of applying said log entry;

and

computer readable program code means for causing a computer to update said mapping table for each said log entry to reflect a type of said log entry.

17. The computer program product according to claim 12, wherein said computer readable program code means for causing a computer to apply said log entry comprises:

computer readable program code means for causing a computer to update a relative byte address (RBA) column in said mapping table for said reorganized version of said data record.

18. A computer program product, comprising:

a computer usable medium having computer readable program code means embodied in said medium for causing a database management system (DBMS) to be reorganized, the computer readable program code means comprising,

computer readable program code means for causing a computer to record a first current relative byte address (RBA) for a log as a first variable, while read/write access to an old area of a table space is retained;

computer readable program code means for causing a computer to perform reorganization Of a data record with an old record identifier (RID) in said old area of said table space such that a reorganized version of said data record has a new RID in a new area of said table space, while read/write access to said old area is retained;

computer readable program code means for causing a computer to store a second current RBA for said log as a second variable;

computer readable program code means for causing a computer to read said first variable;

a computer readable program code means for causing a computer to read said second variable;

computer readable program code means for causing a computer to apply a first log entry including a log entry RID, wherein said log entry RID is said old RID, to said reorganized version of said data record identified by said new RID in said new area by using a RID mapping table to translate said old RID to said new RID, while read\write access to said old area is retained;

computer readable program code means for causing a computer to record a third current RBA for sad foe as a third variable;

computer readable program code means for causing a computer to compare a next iteration, which is a difference between said third variable and said second variable, with a most recent iteration, which is a difference between said second variable and said first variable;

computer readable program code means for causing a computer to implement an action to allow said reorganization to catch up if said next iteration is at least as much as said most recent iteration;

computer readable program code means for causing a computer to quiesce write access to said old area, while said second variable is set to said third variable;

computer readable program code means for causing a computer to apply a second log entry with a second log entry RID, wherein said second log entry RID is said old RID, to said reorganized version or said data record identified by said new RID, by using said RID mapping table to translate said old RID to said new RID, while read-only access is retained;

computer readable program code means for causing a computer to quiesce all access of said table space;

computer readable program code means for causing a computer to convert access from said old area to said new area;

computer readable program code means for causing a computer to create a backup copy of said table space containing said new area;

computer readable program code means for causing a computer to start read/write access to said table space containing said new area; and

computer readable program code means for causing a computer to erase said old area and said RID mapping table.

19. The computer program product according to claim 18, wherein said computer readable program code means for causing a computer to perform reorganization comprises,

computer readable program code means for causing a computer to unload said data record from said old area;

computer readable program code means for causing a computer to reorganize said data record; and

computer readable program code means for causing a computer to reload said reorganized version of data record, except said old RID, in said new area of said table space;

computer readable program code means for causing a computer to insert an entry containing said old RID and said new RID into said mapping table during said reloading step.

20. The computer program product according to claim 18, wherein said first and second log entry each comprise a plurality of log entries, and said article of manufacture further comprises:

computer readable program code means for causing a computer to sort pointers to said first and second log entries by said old RIDs;

computer readable program code means for causing a computer to copy a subset of said first and second log entries;

computer readable program code means for causing a computer to translate said old RID of each of said first and second log entries to said new RID; and

computer readable program code means for causing a computer to translate said old translated first and second log entries by said new RIDs.

21. The computer program product according to claim 20, wherein said computer readable program code means for causing a computer to translate by maintaining said mapping table further comprises:

computer readable program code means for causing a computer to update said mapping table for each of said first and second log entries to reflect a state of said reorganized version of said data record; and

computer readable program code means for causing a computer to update said mapping table for each of said first and second log entries to reflect a state of said log entry.

22. The computer program product according to claim 20, wherein said computer readable program code means for causing a computer to translate by maintaining said mapping table further comprises:

computer readable program code means for causing a computer to update a RBA column in said mapping table for said reorganized version of said data record.