Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-09-25
2001-04-24
Vu, Kim (Department: 2172)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C711S147000
Reexamination Certificate
active
06223176
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the data processing field, and more particularly, relates to a method and computer program product for implementing highly concurrent record insertion in an ordinal number dependent database.
DESCRIPTION OF THE RELATED ART
In a highly concurrent environment where a database workload is performing many insert operations on an ordinal number dependent database, serialization mechanisms used while making the inserted record valid, cause a slowdown in system throughput. The functions performed while making an inserted record valid, referred to in the present description as the validation step, include journalling the insert operation and marking the record as valid such that a retrieve program may view the record. Typically the validation step also ensures that ordinal numbers of a lower ordinal number become valid prior to higher ordinal numbers. In the validation step, serialization is used for three reasons described below.
First, there may be an ordinal number order requirement on a write-ahead database journal for insert type entries. This ordinal number order requirement mandates that inserted records of a lower ordinal number are logged in the journal prior to records of a higher ordinal number, such that if recovery from the journal is necessary, the inserted records will retain their ordinal position. Since the journalling of inserts is performed within this validation step, ordinal number order logging to the journal is guaranteed.
Second, the validation step serialization is used to ensure database retrieval methods can view all the records up to the last valid ordinal number. Since the records become valid in ordinal order, a retrieve program is guaranteed that all records up to the last ordinal number are valid completed inserted records.
Third, the validation step serialization can be used to ensure that no holes in the data space exist when a concurrent insert fails to complete. For example, if there are two concurrent insert processes, such that process A is inserting into ordinal N and process B is inserting into ordinal N+l, and process A fails its insert, the validate step will allow process B to slide its records into ordinal N, thus ensuring no holes are in the database file.
In highly concurrent workloads that perform many database insert operations to a given file, the serialization of the validated step of insert has been shown to be a large limit to a system's scalability. A known insertion method is disclosed in HIGH CONCURRENCY DATA BASE FILE INSERTS, by Ricard et al., IBM Technical Disclosure Bulletin, Vol. 33 No. 6A, November 1990.
A mechanism is needed to remove this serialization from the validation step, while addressing the reasons for the serialization.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an improved method and computer program product for implementing highly concurrent record insertion in an ordinal number dependent database. Other important objects of the present invention are to provide such improved method and computer program product substantially without negative effects and that overcome many disadvantages of prior art arrangements.
In brief, a method and computer program product are provided for implementing highly concurrent record insertion in an ordinal number dependent database. Serialized processing is provided with one concurrent task of multiple concurrent tasks allowed to execute, for allocation of ordinal numbers for record insertion. Concurrent validation processing operations of multiple concurrent tasks are enabled for record insertion in the ordinal number dependent database.
In accordance with features of the invention, a set of counter variables are maintained with the database to enable removal of serialization from the validation phase processing operations for record insertion in the ordinal number dependent database.
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IBM Disclosure Bulletin, “High Currency Data Base File Inserts”, vol. 33, No. 6A, Nov. 1990, pp. 94-103.
IBM Technical Disclosure Bulletin, “Efficient Pipelining Of Data Base Insertions”, vol. 34, No. 6, Nov. 1991, pp. 1-5.
High Concurrecy Data Base (NA901184) Nov. 1990.
Ricard Gary Ross
Rocheleau Richard Miles
Sadecki Wayne Christopher
International Business Machines - Corporation
Ly Anh
Pennington Joan
Vu Kim
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