JPH0877047A - Database backup method - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a database backup method that shortens transaction processing time. [Structure] For a table 104 in which data is stored, a data type field 105 for designating a type for which a process result is always guaranteed by a recovery process from a secondary storage 106 and a type for which only a specific update process is guaranteed. In the database management information, a process for specifying a type for which the processing result of the update statement is guaranteed by the recovery process from the secondary storage 106 and a type for which a certain table is not guaranteed for the transaction accessing the database. The type field 114 is provided in the transaction management information. At the normal end of the transaction, from the type of update statement, the data type of the data type field 105 and the process type of the process type field 114,
It is determined whether or not the update result is reflected on the backup on the secondary storage 106 and the updated value is added to the log information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for creating a backup of a database database and a backup of a memory database having log information on a secondary storage in which all databases are resident on a main storage.

[0002]

2. Description of the Related Art A memory database has a structure in which all tables included in the database are resident in memory.
This is a method for realizing high-speed database access.

Generally, in the operation of a memory database,
Various failures occur such as failures of application programs, failures of systems including a database management system, and failures of secondary storage media such as fixed disks. Therefore, a backup of the database is acquired in the secondary storage, and when a failure occurs, the database is restored from the backed up data.

A conventional backup method for a memory database will be described below.

When an update process based on a statement such as UPDATE / INSERT / DELETE from a database access transaction is performed on a table stored in the memory database,
The updated part is stored in the I / O buffer, and the pre-update value and the post-update value of the update target are stored in the pre-update log buffer and the post-update log buffer in chronological order. Among these, the pre-update log is used for rollback processing for returning the database to the pre-update state on the memory when the transaction ends abnormally. The post-update log is output to the secondary storage when the transaction is normally completed, and prepares for a system failure that occurs while the backup is being updated from the I / O buffer. The I / O buffer is used to update the backup of the database on the secondary storage when the transaction ends normally.

Of these update processes, there are cases where it is not necessary to obtain the update result in the secondary storage. One such example is a representative telephone service that uses a plurality of lines with one telephone number. In general, when managing this example using a database, a table is created that includes columns indicating the telephone numbers and the number of free lines prepared. The following operations are performed on the table. (1) Processing for newly registering a service By the INSERT statement, data including a telephone number to be newly registered and the number of lines prepared for that number is inserted into the table. (2) Call processing to the relevant telephone number The SELECT statement refers to the number of lines currently allowed for the relevant telephone number. Then, if there is a free line, the UPDATE statement updates the table with a value obtained by decrementing the number of allowed lines by one. After that, the connection process to the corresponding line is performed. (3) Call disconnection processing for the relevant line The disconnection processing for the relevant line is performed. The SELECT statement refers to the number of lines currently allowed for the corresponding telephone number, and increments the value by 1, and the UPDA
Update the table with the TE statement. (4) Processing for changing the number of prepared lines The new line number is reflected in the table by the UPDATE statement. (5) Stop processing of representative telephone service Delete the corresponding telephone number inserted in the table by the DELETE statement and the number of lines allowed for that number.

Further, in the recovery processing of this database, since the table is returned to the initial state, all lines are in the unused state. Therefore, the number of lines allowed for one telephone number may be restored to the latest value in any one of the processes (1), (4), and (5) above, and the update of (2) and (3). There is no need to back up the results.

[0008]

As in this example, it may not be necessary to back up the processing result changed by the UPDATE statement depending on the table to be updated. However, in the conventional method, the backup and the log information on the secondary storage are updated even for the update that does not need to be backed up.

I / O is required to update these secondary memories.
Processing is required. Generally, processing time of several milliseconds to several tens of milliseconds is required for I / O processing. for that reason,
Since such unnecessary backup is performed, there is a problem that transaction processing time becomes long.

An object of the present invention is to provide a database backup method that shortens transaction processing time.

[0011]

According to the database backup method of the present invention, for a table in which data is stored, a processing result is always guaranteed by a recovery process from secondary storage, and a specific update process is performed. Database management information is provided with a data type field that is a field that specifies the type guaranteed by the recovery process from the secondary storage, and the update statement processing result is recovered from the secondary storage for the transaction that accesses the database. The transaction management information is provided with a processing type field that is a field for specifying the type guaranteed by processing and the type not guaranteed for a specific table. When the transaction ends normally, insert statement and delete statement To backup on secondary storage The log information of the updated and updated values is added, and for the update statement, the data type field is a type that always guarantees the processing result in the recovery process from the secondary storage, and the processing type field is the processing of the update statement. If the type guarantees the result by the recovery process from the secondary storage, the update result is reflected on the backup on the secondary storage and the updated value is added to the log information, and the data type field is a specific update process. For a type that is guaranteed by the recovery process from the secondary storage only, and if the processing type field is a type that guarantees the processing result of the update statement by the recovery process from the secondary storage, the backup on the secondary storage is also logged. Information is not updated.

[0012]

According to the present invention, a table stored in a database is always backed up at the time of table creation (persistent designation), and depending on the type of transaction for which update processing is performed, backup is not performed (temporary). Add and set the data type field that specifies (Specify) to the schema information. Also, for a transaction that performs an update process, the type (all guarantee specification) that always guarantees the processing result of the UPDATE statement issued from the transaction on the secondary storage, and on the secondary storage depending on the processing target table Add a processing type field that specifies the type that may not be guaranteed (non-guaranteed specification) to the transaction management information and set it.

Then, at the end of the transaction,
The result of the update processing based on the INSERT / DELETE statement is reflected in the output of the updated log and the backup on the secondary storage regardless of the specified values of the data type field and the process type field.

Regarding the result of the update processing based on the UPDATE statement, (1) When the data type field is persistent designation, the output of the updated log and the secondary storage are performed regardless of the designated value of the process type field. When reflected in the backup, (2) When the data type field is temporary specified and the process type field is all guaranteed specified, it is reflected in the output of the updated log and the backup on the secondary storage. 3) When the data type field is temporary designation and the process type field is non-guaranteed designation, the output of the updated log and the reflection on the secondary storage are not reflected.

As described above, according to the present invention, since the update processing by the UPDATE statement from the transaction whose processing type is non-guaranteed is not performed on the table whose data type is temporary, I / O is not performed. Processing time can be shortened.

[0016]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram for explaining a configuration for realizing a process for creating a table according to an embodiment of the present invention.

The table creation mechanism 102 is activated by the table creation instruction 101 and creates a table 104 and a data type field 105 on the memory DB 103. Further, the table creation mechanism 102 creates a backup 107 of the table 104 and a backup 108 of the data type field 105 on the secondary storage 106.

FIG. 2 is a flow chart of a process for creating the table 104 in the configuration shown in FIG. (1) The table creation instruction 101 is the table creation mechanism 1
02 is started (step 200). (2) The table creation mechanism 102 uses the table creation instruction 1
The table 104 is created on the memory DB 103 with the parameter 01 (step 201). (3) The table creation mechanism 102 creates the data type field 105 of the table 104 on the memory DB 103 (step 202). (4) The table creation mechanism 102 uses the table creation instruction 1
The data type field 105
Either a type for always backing up data (designated as persistent designation) or a type for not performing backup (designated as temporary designation) depending on the type of transaction for which update processing is performed (step 20)
3). (5) The table creation mechanism 102 creates the backup 107 of the table 104 on the secondary storage 106 (step 204). (6) The table creation mechanism 102 creates the backup 108 of the data type field 105 on the secondary storage 106 (step 205).

By the above procedure, the table 104 in which the data type is designated is created in the memory DB 103.

FIG. 3 is a diagram for explaining a configuration for realizing a secondary storage update process from a transaction according to the present invention.

The transaction 109 is a start command 110.
And an update instruction 111 and an end instruction 112. The access mechanism 113 performs each process of starting, updating, and ending a transaction.

FIG. 4 is a flowchart of a transaction start process based on the configuration of FIG.

The transaction start processing is performed by the following procedure. (1) The start instruction 110 instructs the access mechanism 113 to start a transaction (step 300). (2) The access mechanism 113 secures the processing type field 114 of the transaction 109 on the memory DB 103 (step 301). (3) The access mechanism 113 always guarantees the processing result of the UPDATE statement issued from the transaction 109 on the secondary storage 106 according to the parameter of the start command 110 (all guarantee specification) and the processing target table. Depending on the case, the type (which is not guaranteed) which may not be guaranteed on the secondary storage 106 is set in the process type field 114 (step 302).

FIG. 5 is a flowchart of a transaction update process based on the configuration of FIG.

Transaction update processing is performed by the following procedure. (1) The update instruction 111 instructs the access mechanism 113 to update the database (step 400). (2) According to the UPDATE / INSERT / DELETE statement issued from the update instruction 111, the access mechanism 113 stores the pre-update values in the table 104 in the pre-update log buffer 115 in chronological order (step 401). (3) The access mechanism 113 updates the update target table 104 according to the UPDATE / INSERT / DELETE statement issued from the update instruction 110 (step 402). (4) Determine the update statement (step 40
3). (5) When the statement issued from the update instruction 111 is INSERT or DELETE, the access mechanism 1
13 indicates the update result of the table 104 performed in (3) as I
The data is stored in the / O buffer 117 (step 404). (6) The access mechanism 113 stores the updated values of the table 104 in the updated log buffer 116 in chronological order (step 405). (7) When the statement issued from the update command 111 is UPDATE, the data type field 105 of the update table 104 is determined (step 406). (8) When the data type field 105 is persistent, the processes (5) and (6) are performed. (9) When the data type field 105 is temporary, the process type field 114 is determined (step 4
07). (10) Transaction processing type field 114
If is all guaranteed, the processes of (5) and (6) are performed. If it is not guaranteed, it ends as it is.

FIG. 6 is a flowchart of the transaction end processing based on the configuration of FIG.

The transaction termination processing is performed by the following procedure. (1) The end instruction 112 instructs the access mechanism 113 to end the transaction (step 500). (2) The end instruction 112 is determined (step 501). (3) The access mechanism 113 receives the CO from the end instruction 112.
When MMIT is issued, the access mechanism 113 adds the contents of the updated log buffer 116 to the updated log file 118 on the secondary storage 106 (step 50).
2). (4) The access mechanism 113 restores the contents of the I / O buffer 117 to the table backup 10 on the secondary storage 106.
7 is reflected (step 503). (5) When the end command 112 is ROLLBACK, the access mechanism 113 instructs the rollback to update the table 104 based on the pre-update log buffer 115 (step 504).

By the above procedure, the result of the UPDATE statement update processing issued from the transaction whose processing type is non-guaranteed for the table whose data type is temporary is not reflected in the secondary storage 106, I / O can be reduced.

FIG. 7 is a diagram for explaining a configuration for implementing a process for restoring the database from the acquired table backup 107 on the secondary storage 106, the updated log information and the data type field 105 according to the present invention. Is.

The restore mechanism 120 performs a process of restoring the database by the restore instruction 119.

FIG. 8 is a flow chart of a database restoration process based on the configuration of FIG.

The database restoration process is performed by the following procedure. (1) The restore instruction 119 instructs the restore mechanism 120 to restore the database (step 600). (2) The restoration mechanism 120 loads the backup 107 of the table 104 on the secondary storage 106 onto the memory DB 103 (step 601). (3) The restoration mechanism 120 sets the value of the data type field 121 on the secondary storage 106 to the data type field 1
05 (step 602). (4) It is determined whether the processes of (2) and (3) have been completed for all the tables (step 603). If not completed, the processes of (2) and (3) are repeated. (5) When the processes (2) and (3) have been completed for all the tables, the restoration mechanism 120 causes the updated log file 1
18 is read in chronological order, and the table 104 on the memory DB 103 is updated.

By the above procedure, the latest value is always guaranteed for the table whose data type is designated as persistent, and the INSERT statement or the processing type is fully guaranteed for the table whose data type is designated as temporary. The latest updated value of the UPDATE statement of a transaction is restored.

[0035]

As described above, according to the present invention, the data type field is provided in the database management information, the process type field is provided in the transaction management information, and only the result of the update process necessary for restoring the database at the time of failure occurs. I / O in the update process
O can be reduced, which has the effect of enabling faster DB access than in the past.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration for realizing a process of creating a table.

FIG. 2 is a flowchart of a process of creating a table.

FIG. 3 is a diagram for explaining a configuration for implementing a process of updating secondary storage 106 from a transaction.

FIG. 4 is a flowchart of a transaction start process.

FIG. 5 is a flowchart of a transaction update process.

FIG. 6 is a flowchart of transaction end processing.

FIG. 7 is a table backup 107 on the acquired secondary storage 106, post-update log information, and data type field 1
5 is a diagram for explaining a configuration for realizing a process of restoring a database from 05. FIG.

FIG. 8 is a flowchart of a database restoration process.

[Explanation of symbols]

 101 table creation instruction 102 table creation mechanism 103 memory DB 104 data type field 105 table 106 secondary storage 107 table backup 108 data type field 109 transaction 110 start instruction 111 update instruction 112 end instruction 113 access mechanism 114 processing type field 115 pre-update log Buffer 116 Post-update log buffer 117 I / O buffer 118 Post-update log file 119 Restore instruction 120 Restore mechanism 200-205 step 300-302 step 400-407 step 500-504 step 600-604 step

Claims (1)

[Claims] 1. All databases are resident in the main memory, and 2
A method of backing up database data on the next storage and a backup of a memory database having log information, in which a processing result for a table storing data is always guaranteed by recovery processing from the second storage, The database management information is provided with a data type field that is a field that specifies the type to be guaranteed in the recovery process from the secondary storage only for a specific update process, and the processing result of the update statement is displayed for the transaction that accesses the database. The transaction management information is provided with a processing type field that is a field for specifying the type guaranteed by the recovery process from the secondary storage and the type not guaranteed for a specific table, and insert statement and delete statement at the normal end of the transaction. about The processing result is reflected in the backup on the secondary storage, the log information of the updated value is added, and in the update statement, the data type field always guarantees the processing result in the recovery processing from the secondary storage. If the processing type field is a type that guarantees the processing result of the update statement by the recovery processing from the secondary storage, the update result is reflected on the backup on the secondary storage and the updated value is added to the log information. The data type field is a type that is guaranteed by the recovery process from the secondary storage only for a specific update process, and the process type field is the type that is guaranteed by the recovery process from the secondary storage for the processing result of the update statement. If so, a database backup method in which neither the backup on the secondary storage nor the log information is updated.