JPH0324643A - Page assigning system for data base - Google Patents

Abstract

PURPOSE:To improve through-put by assigning pages for storing records, and when an allocated page is used for another transaction, assigning another page without waiting the end of the transaction. CONSTITUTION:When the existence of an assignable page can be checked in data base processing, the exclusive logic processing of the assignable page is checked. Then, the result of the trial is checked and whether the page is used for another transaction or not is decided. When the page is used, the search starting position of the page control table is corrected and researched. When the page is not being used by another transaction, the stage flag of the page in the page control table is updated to end the page assignment processing of the data base. Even when the page assignment requests to the data base are generated from plural transactions, processing can be continued without executing exclusive control queuing processing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a database page allocation method, and in particular, to a database processing system having a database that can be referenced and updated by multiple transactions. This paper concerns a database page allocation method that improves execution performance. [Prior Art] In a database processing system that has an exclusive control mechanism that allows multiple transactions to simultaneously refer to and update one database and to perform exclusive control on a page-by-page basis of the database, In order to guarantee consistency, pages updated by a certain transaction must be exclusively locked until the end of that transaction to prevent them from being referenced or updated by other transactions. Here, a page management table is provided to manage each page of the database, and when a request to allocate an arbitrary page to store a record occurs in the processing of one transaction, the page management table is referred to. Then, perform page allocation processing. When performing page allocation processing, in order to prevent double allocation of pages, the exclusive control macro instruction E
Execute exclusive control over other transactions by issuing an NQ macro (see Japanese Patent Laid-Open No. 54-39543)
．． In addition, in a method that performs exclusive control of shared resources using a page management table, if the page in question is being allocated to another transaction, a WAIT macro is issued and wait processing is performed to wait until the page becomes available. Tokukai 1986
(Refer to Publication No.-238939). This reduces the concurrency of transactions. [Problems to be Solved by the Invention] As mentioned above, conventional database processing systems do not take into consideration the fact that waiting due to exclusive control occurs when allocating database pages to each transaction. Therefore, there was a problem that the overhead increased and the throughput of the online system did not improve. The present invention has been made to solve the above problems. An object of the present invention is to provide a database page allocation method that increases the concurrency of transaction processing in a database processing system that has a database that can be referenced and updated by multiple transactions. Another object of the present invention is to suppress waiting due to exclusive control when allocating arbitrary pages of the database in a database processing system having a database that can be referenced and updated by multiple transactions. The purpose is to improve system throughput. The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for Solving the Problems] In order to achieve the above object, in the present invention, in a database processing system that has a database that can be referenced and updated by multiple transactions, a method is used corresponding to each page of the database. A page management table is provided to store usage status information indicating the status, and if any page can be allocated, refer to the usage status information in the page management table, allocate the page to store the record, and assign the allocated page. If a page is being used by another transaction, another page is allocated without waiting for the other transaction to finish. [Operation] According to the above means, in the database processing system, a page management table is provided that stores usage state information indicating the usage state corresponding to each page of the database. When allocating database pages to store records, refer to usage status information in the page management table and allocate pages to store records. In this page allocation process, if the allocated page is being used by another transaction, another page is allocated without waiting for the other transaction to finish. In this way, when there is a request to add a record to the database and there is an overflow, etc. - When allocating a record storage page, the page management table is referenced without exclusive control, and the page allocated from the page management table is used by other transactions. If the page is in use and has an exclusive lock, it does not enter the waiting process for exclusive control of the page, but instead performs the process of allocating another page. In other words, when allocating a record storage page, exclusive control is not applied to the page management table, but an exclusive lock is attempted on the page allocated from the page management table, and if the page is exclusively locked by another transaction, , allocate another page that skips that page. As a result, even if database pages are allocated simultaneously during the processing of multiple transactions, exclusive waits can be suppressed, and the throughput of the online system can be improved. [Example] Hereinafter, an example of the present invention will be explained in detail with reference to the drawings. In all the figures for explaining the embodiments, the same elements are given the same reference numerals, and repeated explanations will be omitted. FIG. 1 is a block diagram showing the configuration of main parts of a database processing system according to an embodiment of the present invention. In FIG. 1, 1 is a data processing device of a database processing system, 2 is a system control section, 3 is a language analysis section, and 4 is a database operation section. Further, 5 is a terminal device, 11 is a database, and 12 is a page management table. The page management table 12 records management information corresponding to each page of the database 11. Although not shown, the terminal device 5 is connected online to the data processing device 11l1, and sends a request for database processing in a transaction to the data processing device III, and the data processing device w1 performs the processing. This database processing is performed by the database operation unit 4 referring to the page management table 12.
Perform this on database 11. Figure 2 is a diagram showing an example of the structure of the page management table in this embodiment. As shown in FIG. 2, the page management table 12 includes page data 12a corresponding to each page of the database 11, an in-use bit 12b indicating whether the page is in use, and a record added to the corresponding page. This is a table in which 2-bit usage status information of the addable bit 12c indicating that there is sufficient area is recorded. For example, if the page in question is a free page, the in-use bit is 1.
2b and the addable bit 12c are both displayed as "0". If the page stores a record, “1” is displayed in the in-use bit 12b, and if there is enough space to add a record, the addable bit 1 is displayed.
"0" is displayed in 2o, and if not, "1" is displayed in the addable bit 12C. Figure 3 is a flowchart showing page allocation processing in database processing. The database page allocation process will be explained with reference to FIGS. 2 and 3. In transaction processing, when a page allocation for storing a record in the database occurs, first, in step 21, the page management table 12 is searched, the "O" bit of the addable bit 12Q is detected, and the corresponding database is allocated. Performs processing to make the page allocatable. Next, in step 22, a check is made to see if there is an allocatable page, and if there is no allocatable page, the process proceeds to error processing. Furthermore, if it is checked in step 22 that there is an allocatable page, the process proceeds to step 23 and an exclusive lock process is attempted for the allocatable page. Next, in step 24, the result of the exclusive lock attempt is checked to determine whether the page in question is being used by another transaction. If the page in question is being used by another transaction, exclusive lock processing will not be effective, so proceed to step 26, perform processing to correct the search start position of the page management table, and repeat the processing from step 21. ．． In addition, in the determination process of step 24, if the page is not being used by another transaction, the process advances to step 25, where the status flag (usage status information) of the page in the page management table is updated, and the database page allocation process is performed. Terminate. Although the present invention has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. [
[Effects of the Invention] As explained above, according to the page allocation method of the present invention, even if database page allocation requests occur simultaneously from multiple transactions, processing can be continued without waiting for exclusive control. Therefore, the throughput of the online system can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the main parts of a database processing system according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of a page management table in this embodiment, and FIG. It is a flowchart showing page allocation processing in database processing. In the figure, 1... data processing device, 2... system control unit, 3... language analysis unit, 4... database operation unit, 5... terminal device, 1
1...Database, 12...Page management table.

Claims (1)

[Claims] 1. In a database processing system that has a database that can be referenced and updated by multiple transactions, a page management table is provided that stores usage state information indicating the usage state of each page of the database, and any page can be If allocation is possible, allocate a page to store the record by referring to the usage status information in the page management table, and if the allocated page is being used by another transaction, terminate the other transaction. A database page allocation method characterized by allocating another page without waiting.