JPH05143435A - Data base system - Google Patents

Abstract

PURPOSE:To provide the data base system which can speedily obtain a processed result corresponding to an inquiry request from a request source. CONSTITUTION:A control means 110 decides whether desired information obtained by accessing a high-speed storing means 140 is valid or not by referring to validity management information corresponding to the desired information and as the result of decision, when the information is valid, the desired information is returned to a request source 20. When it is invalid, the data base stored in a storing means 130 is accessed again and the desired information, which is obtained as the result, satisfying the inquiry request from the request source 20 is returned to the request source 20. Then, the desired information and the validity management information to that desired information is made correspondent and stored in the high-speed storing means 140.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a database system for searching a database in response to an inquiry request from a request source.

[0002]

2. Description of the Related Art In a conventional database system, a database is stored in an external storage device such as a hard disk which has a large capacity but takes a long time to access, and an inquiry result of the database is stored in a memory having a relatively high access speed, such as a cache. There is one that is cached in a storage medium such as a memory. In such a database system, when an inquiry request is made to the database, the result of the inquiry obtained by directly accessing the database is cached in the storage medium, and thereafter, the cached information is used. , The processing efficiency for the inquiry request is improved. However, in such a database system, cached information is assumed to be unchanged, and it is not assumed that inconsistency will occur between the database and cached information. This placed a great deal of restriction on the information that could be cached.

In order to solve this problem, a database system has been proposed in which the contents of the cache memory are also changed every time the contents of the database are changed. This is so that the latest information is always used as the inquiry result by reflecting the contents of changes in the database in the cache information.

[0004]

However, in the above-mentioned conventional database system, the contents of the cache memory are changed every time the contents of the database are changed. Therefore, when the contents of the database are changed, Even if the data corresponding to the contents before the change is not stored in the cache memory, the cache memory is always accessed, and the processing efficiency was very poor.

Particularly, in the case of a distributed database system in which a plurality of database servers are connected to a network, the problem of efficiency is remarkable, and when the contents of the database of a certain database server are changed, the inquiry result to that database is sent. You must also change the cache information in the cache memory of each database server that is caching the. However, if you try to change the cache information of all database servers, managing the cache information becomes complicated,
Moreover, since network management becomes complicated, it is extremely difficult to realize a distributed database system in which the cached contents are changed every time the contents of the database are changed.

An object of the present invention is to provide a database system capable of promptly obtaining a processing result for an inquiry request from a request source.

[0007]

In order to achieve the above-mentioned object, in the present invention, the storage means for storing a database is accessed, and the information corresponding to the inquiry request from the request source obtained by this is sent to the request source. And a high-speed storage unit that stores the desired information and expiration date management information for managing the expiration date in association with each other, in the database system returning to For the desired information obtained by accessing the means, it is determined whether it is valid by referring to the corresponding expiration date management information, and if it is valid, the desired information obtained by the access is returned to the request source. If invalid, the storage means is accessed again, and desired information satisfying the inquiry request from the request source obtained thereby is returned to the request source. And control means for storing in said fast storage means in association with its the desired information and the expiration date management information to it.

[0008]

In the database system according to the present invention, the control means returns the desired information to the request source when the desired information obtained by accessing the high speed storage means is valid, and when the desired information is invalid. Accesses the database stored in the storage means again, returns the desired information satisfying the inquiry request from the request source obtained as a result to the request source, and manages the desired information and the expiration date for the desired information. The information is stored in the high-speed storage means in association with the information.

Therefore, during the period in which the information satisfying the inquiry request from the request source stored in the high-speed storage means is valid, the high-speed storage means only needs to be accessed, which is faster than the case of accessing the storage means. You can get the inquiry result.

[0010]

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

FIG. 1 is a block diagram showing an embodiment of a database system according to the present invention.

In the figure, the database system 10
Is an inquiry request processing unit 110 that receives an inquiry from a client 20 such as a workstation that makes an inquiry to the database, performs a process for the inquiry, a time source 120 that notifies the time, and a database unit 130 that manages the database. And a cache unit 140 that manages cache information.

The database unit 130 includes a database 131 in which various data are stored, and a control unit 132 that accesses the data and obtains information. The control unit 132 is requested by the inquiry request processing unit 110. The processing is performed on the database 131.

The cache unit 140 is a cache memory 141 for storing cache contents which are inquiry results.
And a control unit 142 that accesses the information and obtains information
And the control unit 142 includes the inquiry request processing unit 1
The processing requested by 10 is performed on the cache memory 141.

The time notified from the time source 120 is used by the inquiry request processing unit 110 to know the current time, or the inquiry request processing unit 110 stores the expiration date as expiration date management information in the cached information. It is used when adding information or checking whether the information obtained by accessing the cache memory 141 is valid.

Since the inquiry request processing unit 110 is preset with the information of the kind to be stored in the cache unit 140, the inquiry request processing unit 110 accesses the cache unit 140 by referring to the content of the inquiry from the client 10, or the database unit 130. Determine whether to access. If the inquiry is about a preset type of information to be stored in the cache unit 140, the cache unit 130 is accessed. On the other hand, if not, the database unit 130 is accessed to obtain the result and the result is returned to the client 10.

Since the expiration date information is added to the information (that is, cache information) which is the result obtained by accessing the cache unit 140, the inquiry request processing unit 110.
Determines the validity of the cache information by referring to the expiration date information. If the information obtained from the cache memory 141 is invalid (when the information has expired), the database 131 is directly accessed to obtain the result of the inquiry. In this case, the information obtained from the database 131 is added to the expiration date information and stored in the cache memory 141. On the other hand, when the information is valid, the information from the cache memory 141 is returned to the request source as an inquiry result. Further, when necessary information is not stored in the cache memory 141 at the time of cache access, the database unit 130 is directly accessed to obtain the result of the inquiry, and the expiration date information is added to the result of the inquiry so that the cache unit 140
Request storage.

The present invention does not assume any means for updating the cached data when the data in the database is changed. Instead, add time to the cached information after a certain period of time from the time it was cached, that is, expiration date information, and refer to the expiration date information to determine the validity of the cached information. There is.

This is possible because the query result obtained by accessing the database information which is not changed so much, for example, the database information about the company organization, is cached in the cache memory.

In this embodiment, the storage means described above is realized by the database section 130, the high speed storage means described above is realized by the cache section 140, and the control means described above is realized by the inquiry processing section 110. ing.

FIG. 2 shows an example of a network system having a database system according to the present invention.

In the figure, the network system is
A device 200 such as a computer or a workstation having the database system 10 shown in FIG. 1 and a plurality of clients 210, 220, 230 are connected to a network 240. Device 200
Then, upon receiving an inquiry request from each client input via the network 240, the database system 10 processes the request,
The result is returned to the client.

Next, the processing for the inquiry request by the device 200 will be described with reference to FIG.

FIG. 3 is a flow chart showing the processing operation for an inquiry request. In this flow chart, U indicates a user and G indicates a group.

Now, as an example, consider a database system in which information as to whether or not the user U is a member of the group G is cached. Therefore, in order to answer such an inquiry, it is assumed that the database 131 stores a list 131A of members of the group G as shown in FIG. Inquiries about whether a certain user is a member of a predetermined group, which is considered here, are frequently made in directory services and the like.

Further, the inquiry request processing unit 11 in the device 200
0 is the type of information that should be stored in the cache unit 140 for the information about the members of the group,
That is set in advance. Note that, here, it is assumed that the “result of inquiry as to whether a specific user is a member of a specified group” is cached in the cache memory 141, and the expiration date of the cached information is 1 Suppose it's time.

Now, referring to FIG. 3, the process for an inquiry will be described. For example, an inquiry request from the client 210 is sent to the device 200 via the network 240.
In the device 200 to which the inquiry request has been input, the inquiry request processing unit 110 checks whether the inquiry is of the form "user is a member of a group" (step 310).

If the inquiry has different contents, the inquiry request is sent to the database unit 130 and the inquiry result is obtained (step 320).
In step 310, "user is member of group"
In response to the inquiry, the inquiry request is sent to the cache unit 140, and an inquiry is made as to whether the user U has information on whether or not the user U is a member of the group G (step 330). Cache unit 140
Then, the control unit 142 searches the cache memory 141, and if there is no information as a result of the search, the result is an inquiry result. On the other hand, if there is such information, the corresponding cache information and expiration date information are inquired. As a result, it is returned to the inquiry request processing unit 110.

The inquiry request processing section 110 includes a control section 142.
Based on the inquiry result from (1), it is determined whether or not the information indicating whether the user U is a member of the group G is stored in the cache memory 141 (step 340). Here, if the inquiry result is the corresponding cache information and expiration date information, the validity of the cache information received from the cache unit 140 is checked by referring to the expiration date information (step 350).

If the cache information is valid, that is, if the information is cached within one hour, the cache information received from the cache unit 140 is returned to the client 210 as a result of the inquiry (step 360).

If the information "whether or not the user U is a member of the group G" is not stored in the cache memory 141 in the above step 340, the inquiry request processing unit 110 invalidates the information received in the above step 350. If (1 hour has passed), a request is sent to the database unit 130 and the inquiry result is obtained (step 370). At this time, the database unit 1
In 30, the control unit 132 searches the database 131 and returns desired information to the inquiry request processing unit 110.

Further, the inquiry request processing section 110 passes the information obtained from the database section 130 to the client 210, adds a time stamp to the information (cache information), and passes it to the cache section 140 (step 38).
0). In the cache unit 140, the control unit 142
However, the cache information with the time stamp is stored in the cache memory 141. The time stamp as the expiration date management information may be information indicating the current time or information indicating the expiration date (time after one hour).

By the way, when the query request processing unit 110 accesses the database unit 130, the database 1
For example, the information “user U is a member of group G” stored in 31 is “user U is group G”.
If the information has been changed to "is not a member of", the cache information in the cache memory 141 is updated.

Next, FIG. 4 shows an example of a network system when the database system is distributed.

The network system shown in this figure has the same configuration as the network system shown in FIG.
It has a configuration in which a device 400 having the same function as is added. In this figure, parts that perform the same functions as the components of the system configuration diagram shown in FIG. 2 are assigned the same reference numerals.

Here, for example, when the client 210 requests an inquiry from the device 200, the device 20
0 is the local database system and device 400 is the remote database system.

Here again, as described above, it is assumed that an inquiry is made as to whether or not a user is a member of a predetermined group. In this case, only the database 131 of the device 400 has the list 131A shown in FIG. Is stored.

When the client 210 makes an inquiry request to the device 200, the inquiry process is first performed in the local database system. At this time, the database 141 of the device 200
When the target data does not exist in the device, an inquiry request is sent from the device 200 to the device 400 existing remotely. The device 400 returns the information obtained by accessing the database 131 and the cache memory 141 to the device 200. The device 200 stores the information returned from the device 400 in its own cache memory 141 as necessary and uses it for the next and subsequent inquiry requests.

In the above-described embodiment, the case where the inquiry request processing unit and the cache unit are provided in the same physical medium as the database unit has been described, but the present invention is not limited to this, and the inquiry request processing is performed on the client side. It is also possible to provide a section and a cache section. In this case, since the client does not need to access the cache unit through the communication line (network), the processing efficiency for the inquiry request can be further improved as compared with the processing efficiency in the above-mentioned embodiment.

As described above, according to the present embodiment, the inquired information (that is, cache information) is stored in the cache memory, and when another inquiry request is made for the same information, the request (inquiry request) is made by the cache information. ) Is processed. That is, since the access to the cache memory is processed more quickly than the case of directly accessing the database, the client can obtain the result regarding the inquiry earlier.

Further, even if the contents of the database are changed, the cache information in the cache memory is not updated accordingly, so compared with the conventional method of updating the cache contents when the database is changed. Thus, it is possible to provide a database system having a simple structure and high efficiency.

Particularly, in the distributed database system, the update processing of the cache information in each cache memory of each database system which caches the inquiry result to the database is reduced, and the cache information management and the network management are performed. It will be easy. This is effective in a situation where inquiries are concentrated in a short time on information that is relatively updated.

[0043]

As described above, according to the present invention, desired information, which is stored in the high-speed storage means and satisfies the inquiry request obtained by accessing the storage means, corresponds to that information. If the desired information obtained by accessing the high-speed storage means is determined to be valid by referring to the expiration date information, the desired information is used as the request source. Since it is returned, the processing result for the inquiry request can be quickly obtained.

Even if the contents of the database in the storage means are changed, the contents stored in the high-speed storage means are not updated accordingly, so that
Update processing for the high-speed storage means is reduced, so that in the distributed database system,
Management of cache information and network management becomes easy. Therefore, even in the distributed database system, it is possible to quickly obtain the processing result for the inquiry request.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a database system according to the present invention.

FIG. 2 is a diagram showing an example of a network system configured to have a database system according to the present invention.

FIG. 3 is a flowchart showing the processing operation of this embodiment.

FIG. 4 is a diagram showing an example of a network system including a distributed database system to which the database system according to the present invention is applied.

[Explanation of symbols]

10 ... Database system, 20 ... Client, 1
10 ... Inquiry request processing unit, 120 ... Time source, 13
0 ... database unit, 131 ... database, 132,
142 ... Control unit, 140 ... Cache unit, 141 ... Cache memory.

Claims (1)

[Claims] 1. A database system for accessing a storage means for storing a database and returning information obtained in response to an inquiry request from a request source to the request source, which can be accessed faster than the storage means. Also, a high-speed storage unit that stores the desired information and the expiration date management information for managing the expiration date in association with each other, and the corresponding effective information about the desired information obtained by accessing the high-speed storage unit. The expiration date management information is referred to determine whether it is valid, and if it is valid, the desired information obtained by the access is returned to the request source, and if it is invalid, the storage unit is accessed again, The desired information satisfying the inquiry request from the request source thus obtained is returned to the request source, and the desired information and the expiration date management information for the desired information are returned. Database system in association, characterized in that and control means for storing in said fast storage means.