JPH01189741A - Journal output system - Google Patents

Abstract

PURPOSE:To reduce an amount of files to be preserved by writing out only the latest update journal record in the same page on a file when plural user processes update the same data base file in the same job according to the expansion of a system. CONSTITUTION:When the user processes 11 and 12 update the page of the data base file 21, respectively, an updated page is held at a journal buffer 52 as managing by a page managing part 51 is a journal managing table 50, and the file 21 is updated by using the updated page at a time when the processes 11 and 12 complete the update, respectively. Also, an operator issues a request to output all of the pages held at the buffer 52 to a journal file 60 based on an operator command from a console 70, and the managing part 51 is inspected by a journal write out part 43 according to the request, then, all of the pages are written out on the file 60 from the buffer 52.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is capable of outputting only the most recently updated journal record to a journal file when multiple user processes update the same journal record. , relates to a journal output method that makes it possible to reduce the number of journal records output to a journal file.

(Prior Art) Conventionally, in Kaki's journal output method, all journal records for which an update request has been made are output to a journal file after the update, regardless of whether it is necessary.

(Problem to be Solved by the Invention) As the system becomes larger, the conventional journal output method described above is used to output the updated journal for the same page when multiple user processes update the same database file in the same job. As a large number of records are output, the amount of journal records that must be saved increases. Additionally, when performing file recovery processing in the event of a magnetic disk failure using journal records, there is an unresolved problem in that the same page in the database file must be updated many times, resulting in wasted processing time. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the journal output method provided by the present invention is a journal output method for each of a plurality of user processes or a database management system (DB\S/DataBa5eM).
A request is issued to ana (leInent System) to update the journal record in the database file, and the DBMS that receives this request outputs the updated journal record to the journal file to the journal output control unit. A journal output method of a computer system that issues requests, wherein a journal management table that temporarily holds pages containing the updated journal records in the database file is stored in main memory and updated by the user process. When updating the requested journal record,
If the page containing this journal record is already held in the journal management table, update the journal record in that page; if the page is not held, update the journal record in the database file. means for reading the page and registering it newly in the journal management table, and then updating the journal record in the registered page; and when the journal management table is full, the oldest updated The journal output control unit includes means for outputting pages to the journal file to create free pages, and means for outputting all the journal records registered in the journal management table to the journal file by an operator command. It is characterized by

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram of a journal output method according to an embodiment of the present invention.

In the figure, 10 is a user process input to the computer system, 20 is a database file updated by the user process 10, 30 is a DBMS that manages the database file 20, and 40 is a device that manages or outputs updated journal records. A journal output control unit, 50 is a journal management table that temporarily stores updated journal records, 60 is a journal file that ultimately stores updated journal records, and 70 is used to input instructions from the operator. Each console is shown below.

The user process 10 issues a request to the DBMS 30 to update the journal record in the database file 20. Upon receiving this request, the 8MS 30 issues a request to the journal output control unit 40 to output the updated journal record. The journal output control unit 40 first checks the journal management table 50, and if a page containing this updated journal record exists, updates that page, and if it does not exist, updates the page to the database file. The page is read from 20 and registered in the journal management table 50, and the page is updated.

If there is no free page in the journal management table 50 and no registration is received, the oldest updated page is output to the journal file 601\ to ensure a free page.

After updating the page of the journal management table 50 in this way, the journal output control unit 40 updates the DB
The MS 30 is notified of this fact. DBMS 3
Upon receiving this notification, process 0 updates the database file 20 as requested by the user process 10.

Further, the operator can input an instruction to the journal output control unit 40 from the console 70 at any time to output journal records in the journal management table 50 to the journal file 60.

FIG. 2 is a block diagram showing the configuration of this embodiment. 1st
The conceptual diagram of the figure is shown in detail, and the same parts are represented by the same reference numerals.

There are user processes 11 and 12 as user processes 10 input into the computer system, and database files 21 and 22 as database files 20 to be updated. In addition, the journal output control unit 40
consists of a page update section 41, a page reading section 42, and a journal writing section 43, and a journal management table 5.
0 consists of a page management section 51 and a page buffer 52.

User process 11 issues a DML command to DBMS 30 to update the journal record contained in page i of database file 21, for example. The DI3MS 30 requests the page update unit 41 to output the updated journal record.

The page update unit 41 inspects the page management unit 51 and determines whether the page i including this journal record or the page buffer 5
2, it requests the page reading unit 42 to read page i from the database file 21. The page reading unit 42 reads page i from the database file 21 into the page buffer 52, and at the same time updates the page management unit 51 to a state in which page i is registered.

As a result, the page update section 41 once again updates the page management section 5.
1, page i can be found in page buffer 52 at -7=. Therefore, the page update unit 41 updates page i and notifies the DBMS 30 that output of the updated journal record has been completed. D
Upon receiving this notification, the BMS 30 updates the database file 21 and sends the DML to the user process 11.
Notify that the instruction has been completed.

After that, user process 12 or database file 2
When issuing a DML command to update page i of 1, the DBMS 30 updates the page update unit 41 in the same way as described above.
A request to output the updated journal record is not issued. The page update unit 41 checks the page management unit 51, finds that page i already exists in the page buffer 52, updates this page i, and notifies the DMBS 30 that the output has been completed. The subsequent operations are similar to those described above.

As this operation is repeated, the page buffer 5
2, when there are no more free pages, the page update unit 41, which has received a request to output the updated journal record from the DBMS 30, requests the journal write unit 43 to reserve a free page in the page buffer 52. .

The journal writing unit 43 inspects the page management unit 51, selects the oldest updated page, writes it to the journal file 60, and updates the page in the page management unit 51 to a free page state. As a result, the page updating unit 41 checks the page management unit 51 and finds that there is an empty page, so it can request the page reading unit 42 to read a new page. Then, the read page is updated with the updated journal record in the same manner as described above.

As described above, when each of the user processes 11 and 12 updates page i of the database file 21, the updated page i is held in the journal buffer 52 while being managed by the page management unit 51 in the journal management table 50. and user processes 11 and 1
2, the database file 21 is updated with the updated page i.

Further, when the user processes 11 and 12 are terminated, the operator issues a request to output all pages held in the journal buffer 52 to the journal file 60 using an operator command from the console 70. The journal writing unit 43 inspects the page management unit 51 according to this request, and writes and outputs all registered pages from the page buffer 52 to the journal file 60.

In this way, only the latest journal records can be output to the journal file 60.

Next, the operation of this embodiment will be explained using the general flowchart shown in FIG.

In step 100, the user process 10 uses the DBM 33
Issue a DML command to 0. In step 110, the DBMS 30 issues a journal output request to the page update unit 41. The page update unit 41 performs step 1
In step 20, a check is made for free pages, and if there are no free pages, the process proceeds to step 130. In step 130, the journal writing unit 43 writes the oldest updated page to the journal file 60. Next, in step 140, the page update unit 41 checks whether a page including the journal record to be updated exists, and if it does not exist, the process proceeds to step 150, step 1.
At 50, the page reading unit 42 reads the page from the database file 20. Page update section 41
updates the page in step 160, and the DBMS 30 updates the database file 20 in step 170, and ends the process.

FIG. 4 shows an outline of the operation of this embodiment according to instructions from the operator.

The operator via the console 70 performs step 200
Issue operator commands with . When the journal writing unit 43 receives this command, in step 210,
The page management unit 51 checks existing pages. If a valid page exists, in step 220 this page is written to the journal file 60, and in step 23
0, the page management section 51 is updated. This operation is repeated until there are no valid pages in the check for existing pages in step 110.

(Effects of the Invention) As explained above, the present invention has the advantage that when multiple user processes update the same database file in the same work as the system becomes large, the same page can be updated to the latest version. Since only journal records are written to the journal file, the amount of journal files to be saved can be reduced. In addition, when performing file recovery processing using updated journal records in the event of a magnetic disk failure, the same page only needs to be updated once, which can reduce the time required for recovery processing. ) It has a soothing effect.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a journal output method according to an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of this embodiment, Fig. 3 is a general flowchart showing the operation of this embodiment, and Fig. 4 is a 3 is a schematic flowchart showing the operation of this embodiment according to instructions from an operator. 10, 11, 12... user process, 20.21.
22...Database file, 30...DBMS
, 40... Journal output control unit, 41... Journal update unit, 42... Page reading unit, 43... Journal writing unit, 50... Journal management table, 51... Page management unit, 52...Page buffer, 60...Journal file, 70...Console.

Claims (1)

[Claims] Each of a plurality of user processes issues a request to the database management system to update a journal record in a database file, and upon receiving this request, the database management system sends the updated journal to the journal output control unit. In a journal output method of a computer system that issues a request to output records to a journal file, a journal management table is provided in main memory for temporarily holding pages including the updated journal record in the database file, and the When updating the journal record requested by a user process, if the page containing this journal record is already held in the journal management table, the journal record in that page is updated. , means for reading the page from the database file and newly registering the page in the journal management table and then updating the journal record in the registered page if the page is not retained; A means for creating a free page by outputting the oldest updated page to the journal file when the management table is full, and a means for creating a free page by outputting the oldest updated page to the journal file, and all the journal records registered in the journal management table by an operator command. The journal output method is characterized in that the journal output control unit includes means for outputting the information to the journal file.