JPH10289135A - Data base retrieval system provided with cache function of retrieved result - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the preparation of the cache of a data base depending on retrieval conditions and an efficient data base retrieval processing utilizing it. SOLUTION: At the time of a retrieval request from a client 105, a server 101 executes the retrieval only to a record inside the data base 102 changed or added after the execution date and time of the same retrieval condition as the retrieval condition of the retrieval request of this time on the cache 104 by referring to a retrieved result cache file 104 and a data base updating history table 103, eliminates the record corresponding to the record inside the data base 102 eliminated after the execution date and time from a retrieved result record group corresponding to the same retrieval condition inside the cache 104, connecting the retrieved result record group on the cache 104 obtained as the result and the record group obtained as the result of the new retrieval of this time to the data base 102 and thus, obtains the updated retrieved result record group for the retrieval request of this time and returns it to the client 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for caching search data in a database system.

[0002]

2. Description of the Related Art In a conventional database search system, a database server searches a database file stored on a disk in response to a search request from a client,
The operation of returning the search result to the client has been executed for each search request.

Therefore, conventionally, every time a new search request is generated, a search is performed on the database file on the disk every time, even if the search conditions are the same as the search conditions of the previous search request. Therefore, the same amount of time is required for the search process every time.

[0004] However, in actual business processing, etc., the search conditions for each search request are very often the same.
Searching the database file on the disk for each such search request has a problem that it is very inefficient.

Conventionally, there has been known a method of caching a part of data of a database file stored on a disk in a main storage memory. They are cached sequentially, and the cache efficiency was not always good.

An object of the present invention is to realize creation of a database cache depending on a search condition and efficient database search processing using the cache.

[0007]

According to a first aspect of the present invention, there is provided:
A database search device having a function of caching a database search result is assumed.

[0008] First, there is provided a search result cache means (search result cache file 104) for storing, as cache data, search conditions, search dates and times, and search result record groups corresponding thereto for the database.

Next, change, add,
Alternatively, a database update history table means (database update history table 103) for recording the history of deleted records is provided.

Next, when a search request is issued, cache data search means (steps 402, 403, and 403 in FIG. 4) for searching cache data having the same search condition as the search request in the search result cache means. 40
5).

Next, by referring to the database update history table means, it is possible to respond to a search request only for records in the database changed or added after the search date and time in the cache data searched by the cache data search means. And a database search executing means (steps 408 to 410 in FIG. 4) for executing a new search.

[0012] Next, by referring to the database update history table means, a record corresponding to a record in the database deleted after the search date and time from a search result record group in the cache data searched by the cache data search means. Cache data deleting means (steps 406 and 407 in FIG. 4) for deleting the entry of
Having.

Next, search result record combining means (step 411 in FIG. 4) for combining a record group newly searched from the database by the database search executing means with a search result record group in the cache data which has been deleted. Having.

Next, cache data updating means for re-storing the search result record group combined with the search condition of the search request and the new search date and time as new cache data in the search result cache means (step 412 in FIG. 4). Having.

Further, there is provided search result output means (step 413 in FIG. 4) for outputting the combined search result record group as a search result for the search request. According to the configuration of the first aspect of the present invention described above, the search is executed only for the records in the database changed or added after the execution date and time of the same search condition as the search condition of the current search request. Thereby, it is possible to speed up the search process and reduce the load on the database server due to the reduction in the number of accesses to the database.

Next, a second embodiment of the present invention has a function of caching a search result of a database, and is provided with a client computer device (client computer 10).
It is assumed that the server computer apparatus (server computer 101) executes a search process on the database (database 102) held by the server computer apparatus (server computer 101) in accordance with the search request from 5).

First, the client computer has the following means. That is, the client computer device first has a search result caching means for storing, as cache data, a search condition, a search date and time, and a search result record group corresponding thereto for the database in the server computer device.

Next, the client computer device:
When a search request is issued, there is provided a cache data search means for searching cache data having the same search condition as the search condition of the search request in the search result cache means.

Next, the client computer device:
Search request transmitting means for transmitting the search request to the server computer together with the search date and time in the searched cache data.

Next, the client computer device:
A cache data deleting unit that deletes an entry of a record corresponding to the deleted record information returned from the server computer from the search result record group in the cache data searched by the cache data searching unit;

Next, the client computer device:
There is provided a search result record combining means for combining the new search result record group returned from the server computer device and the search result record group in the deleted cache data.

Next, the client computer device:
There is provided a cache data updating means for re-storing the search condition of the search request and the search result record group combined with the new search date and time as new cache data in the search result cache means.

The client computer has a search result output means for outputting the combined search result record group as a search result for the search request. On the other hand, the server computer has the following means.

That is, the server computer device firstly
It has a database update history table means for recording the history of changed, added, or deleted records in the database.

Next, by referring to the database update history table means, the server computer device can record a record in the database changed or added after the search date and time transmitted by the search request transmitting means in the client computer device. And a database search execution unit that obtains a new search result record group by executing a new search corresponding to the search request transmitted by the search request transmission unit.

Next, the server computer device refers to the database update history table means to obtain information corresponding to the record in the database deleted after the search date and time transmitted by the search request transmitting means in the client computer device. As deletion record information.

The server computer has a search result returning means for returning the new search result record group and the deleted record information to the client computer which has transmitted the search request.

According to the configuration of the second embodiment of the present invention described above, in addition to the same operation as the configuration of the first embodiment of the present invention described above, especially in a case where the number of search result records is large, The amount of communication data between the client computer device and the server computer device can be significantly reduced.

Further, the configuration of the second aspect of the present invention has an effect that the search result cache file for each client computer device is optimized based on the tendency of specifying the search condition in each client computer device. .

According to the present invention, when used by a computer, a function similar to the function realized by the above-described configuration of the first or second aspect of the present invention is implemented by a computer, a server computer, or a client computer. It may be configured as a computer-readable storage medium to be executed by the device.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is a system configuration diagram of a first embodiment of the present invention.

In the first embodiment, a database 102, which manages a database 102 stored on a disk (not shown), executes a database server process (not shown).
A search result cache file 104 that stores search conditions, search dates and times, and a search result record group corresponding to them, and a database update history table 103 that records the history of changed, added, or deleted records in the database 102. Provided.

Then, the client computer 105
When a search request is made from the server, the database server process (not shown) on the server computer 101 refers to the search result cache file 104 and the database update history table 103 to search for the current search request in the search result cache file 104. The search is executed only for the records in the database 102 changed or added after the execution date and time of the same search condition as the condition, and the database 1 deleted after the execution date and time is executed.
02 is deleted from the search result record group corresponding to the same search condition in the search result cache file 104 in the search result cache file 104, and the resulting search result record group in the search result cache file 104 and the database 102 are deleted. By combining with the records obtained as a result of this new search, the updated search result records for the current search request are obtained,
It is returned to the client computer 105.

As described above, in the first embodiment,
A feature related to the present invention is that efficient search processing according to search conditions can be executed. FIG. 2 is a diagram showing a data configuration of the database update history table 103 of FIG.

For records changed, added or deleted based on a record update request (see FIG. 1) from the client computer 105 in the database 102, a unique record ID in the database 102
The record ID, the update date and time, and the update content (change, addition, or deletion) are recorded in the database update history table 103 in the data format shown in FIG.

FIG. 3 is a diagram showing the data structure of the search result cache file 104 of FIG. In this file, based on a search request from the client computer 105, a search condition, a search date and time, a search result record group, and respective record IDs are recorded in a data format shown in FIG.

FIG. 4 shows the server computer 10.
3 is an operation flowchart illustrating a control operation performed by a database server process in the first embodiment. First, the database server process receives a search request (search request) from the client computer 105 (step 40).
1).

Next, the database server process searches the search result cache file 104 for cache data (data in the format shown in FIG. 3) that matches the search conditions specified by the search request (step 402).

Subsequently, the database server process
It is determined whether matching cache data is found as a result of the search in step 402 (step 40).
3). If no matching cache data is found and the determination in step 403 is NO, the database server process searches all records in the database 102 for records that match the search condition specified by the search request received in step 401. Search (step 404).

On the other hand, if matching cache data is found and the determination in step 403 is YES, the database server process executes a series of processes in steps 405 to 411 described below.

First, the database server process obtains the previous search date and time (see FIG. 3) from the matched cache data (step 405). Next, the database server process acquires, from the database update history table 103, the record ID of the record deleted after the previous search date and time acquired in step 405 (step 406).

Next, the database server process retrieves an entry of a search result record having a record ID corresponding to the record ID of the deleted record from the search result record group in the cache data matched by the search in step 402. It is deleted (step 407).

Next, the database server process determines from the database update history table 103 in step 40
The record ID of the record changed or added after the previous search date and time acquired in step 5 is acquired (step 40).
8).

Next, the database server process searches the database 102 for a record corresponding to the record ID acquired in step 408 and acquires it (step 409).

Further, the database server process transmits the record acquired in step 409 to step 4
By executing a search under the search condition specified by the search request received at 01, a record that matches the search condition is obtained (step 410).

Then, the database server process
The group of records acquired in step 410 is
The search result records in the cache data matched by the search in step 2 are combined (step 411).

After the processing of step 411 or step 404 described above, the database server process
A search result record group obtained by the combining process in step 411 or the search process in step 404 together with the search condition specified by the search request received in step 401 and the search date and time as the current date and time, and the respective record IDs Is stored in the search result cache file 104 (step 412).

Finally, the database server process:
The search result record group saved in the search result cache file 104 in step 412 is delivered as a search result to the client computer 105 that transmitted the search request (search request) received in step 401 (step 413).

As described above, under the control operation according to the first embodiment, the record in the database 102 changed or added after the execution date and time of the same search condition as the search condition of the current search request. By executing the search only for, the speed of the search process can be increased and the load on the database server can be reduced due to the decrease in the number of accesses to the database. <Second Embodiment> FIG. 5 is a system configuration diagram of a second embodiment of the present invention.

The structure shown in FIG. 5 is equivalent to the first structure shown in FIG.
The difference from the configuration of the first embodiment is that the first embodiment shown in FIG.
In the second embodiment shown in FIG. 5, the search result cache file 104 stored in the server computer 101 is stored in each client computer 105 in the second embodiment.

In this case, a database client process (not shown) executed in the client computer 105 is executed by the server computer 101.
When the search request is executed, first, similarly to steps 402, 403, and 405 of FIG. 4, the search condition specified by the search request is retrieved from the locally stored search result cache file 104. And retrieves the previous search date and time from the cache data that matches.

Thereafter, the client computer 105
The above database client process delivers the acquired previous search date and time to the server computer 101 together with the above search request.

The database server process on the server computer 101 executes a process similar to the steps 408 to 410 in FIG. , And a record corresponding to the acquired record ID is retrieved from the database 102 to acquire the record ID. The acquired record is further retrieved according to the retrieval condition specified by the retrieval request received from the client computer 105. By executing a search, a record matching the search condition is obtained.

The database server process on the server computer 101 returns a new search result record group newly searched from the database 102 to the client computer 105.

Further, the database server process on the server computer 101 reads the database update history table 103 from the database update history table 103 in the same manner as in step 406 of FIG.
It acquires the record ID of the record deleted from the previous search date and time received from the client computer 105 and returns it to the client computer 105.

The database client process on the client computer 105 proceeds to step 40 in FIG.
In the same manner as in 7, the server computer retrieves a search result record group in the cache data that matches the search condition specified by the search request, which has been previously searched and extracted from the locally held search result cache file 104. The entry of the search result record having the record ID corresponding to the record ID of the deleted record returned from the server 101 is deleted, and the new search result record group returned from the server computer 101 is deleted in the same manner as in step 411 of FIG. Is combined with a search result record group in the cache data, and the combined result is used as a response to the search request by the client computer 105
Output above.

The database client process on the client computer 105 is the same as step 412 in FIG. 4, and is the above-mentioned combination result together with the search condition specified by the search request and the search date and time as the current date and time. The search result record group and each record ID are stored in the search result cache file 104 held locally.

Under the control operation according to the second embodiment described above, in addition to the effects of the first embodiment described above, especially in a case where the number of search result records is large, the client computer 105 It is possible to greatly reduce the amount of communication data between the server and the server computer 101.

In the second embodiment, the search result cache file 104 for each client computer 105 is stored in each client computer 105.
There is also an effect that the search condition is optimized based on the specified tendency of the search condition. <Other Embodiments> In the first and second embodiments described above, the search condition is recorded in the search result cache file 104. However, the search condition to be cached and the search result It is also possible to adopt a configuration in which records are stored in separate cache files.

The cache data may be stored in the main memory instead of the file (or not only the file). Further, when the database server process accesses the database 102 based on the database update history table 103, instead of using the record ID as a key, the correspondence between the record ID and the position (address) of the record in the database file is used. May be separately prepared as an index file, and the database 102 may be accessed based on the index file.

The present invention relates to a floppy disk or a CD storing a computer program having a function realized by the first or second embodiment of the present invention.
-A storage medium such as a ROM disk, an optical disk, and a portable (removable) hard disk is also claimed.

[0062]

According to the configuration of the first aspect of the present invention, the search is performed only on the records in the database changed or added after the execution date and time of the same search condition as the search condition of the current search request. By executing this, it is possible to speed up the search process and reduce the load on the database server due to the reduction in the number of times of accessing the database.

According to the configuration of the second aspect of the present invention, in addition to the same effects as the above-described configuration of the first aspect of the present invention, especially in a case where the number of search result records is large,
The amount of communication data between the client computer device and the server computer device can be significantly reduced.

Further, according to the configuration of the second aspect of the present invention, the search result cache file for each client computer is optimized based on the tendency of specifying the search condition in each client computer. Also have.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram according to a first embodiment of this invention.

FIG. 2 is a configuration diagram of a database update history table.

FIG. 3 is a configuration diagram of a search result cache file.

FIG. 4 is an operation flowchart of the first embodiment of the present invention.

FIG. 5 is a system configuration diagram according to a second embodiment of this invention.

[Explanation of symbols]

 Reference Signs List 101 server computer 102 database 103 database update history table 104 search result cache file 105 client computer

Claims (8)

[Claims] 1. A database search device having a function of caching a search result of a database, wherein a search result cache means for storing, as cache data, a search condition, a search date and time, and a search result record group corresponding to the search condition for the database. Database update history table means for recording the history of changed, added, or deleted records in the database; and when the search request is issued, the same search condition as the search condition in the search result cache means in the search result cache means. A cache data search unit for searching cache data having a condition; and the database changed or added after a search date and time in the cache data searched by the cache data search unit by referring to the database update history table unit. A database search execution unit that executes a new search corresponding to the search request only for the record of the above; and a search in the cache data searched by the cache data search unit by referring to the database update history table unit. A cache data deletion unit that deletes, from the result record group, an entry of a record corresponding to a record in the database deleted after the search date and time; and a record group newly searched from the database by the database search execution unit. Search result record combining means for combining a search result record group in the cache data from which the deletion has been executed; a new cache for the search condition of the search request, a new search date and the combined search result record group The search result cache as data Cache data updating means for re-storing in the cache means, and search result output means for outputting the combined search result record group as search results for the search request. Database search device. 2. A database search method having a function of caching a search result of a database, wherein a search condition, a search date and time, and a search result record group corresponding thereto are stored in a search result cache device as cache data. The history of records that have been changed, added, or deleted in the database is recorded as a database update history table, and when a search request is issued, the same search condition as the search condition of the search request is issued in the search result cache device. By searching for cache data having the following, and referring to the database update history table, only the records in the database changed or added after the search date and time in the searched cache data correspond to the search request. Perform a new search to By referring to the database update history table, from the search result record group in the searched cache data, delete the entry of the record corresponding to the record in the database deleted after the search date and time, from the database The newly searched record group and the search result record group in the cache data from which the deletion has been executed are combined, and the search condition of the search request, a new search date and the combined search result record group are newly added. Retrieving the combined search result record group as search results in response to the search request. Method. 3. A client / server type database search system having a function of caching a search result of a database and executing a search process on a database held by a server computer in accordance with a search request from a client computer. A search result cache unit for storing, as cache data, search conditions, a search date and time, and a search result record group corresponding to the search conditions and the search date and time for the database in the server computer device; A cache data search unit that searches for cache data having the same search condition as the search condition of the search request in the search result cache unit; and stores the search request together with a search date and time in the searched cache data. Search request transmitting means for transmitting to the server computer device, and an entry of a record corresponding to the deleted record information returned from the server computer device, from a search result record group in the cache data searched by the cache data search means. A cache data deleting unit to be deleted; a search result record connecting unit that connects a new search result record group returned from the server computer device and a search result record group in the deleted cache data; Cache data updating means for restoring the search condition, new search date and time, and the combined search result record group as new cache data in the search result cache means; and performing the search on the combined search result record group Search results for the request Database update history table means for recording the history of changed, added, or deleted records in the database in the server computer device; andthe database update history table means in the server computer device. By referring to the search request transmitted by the search request transmitting unit only for records in the database changed or added after the search date and time transmitted by the search request transmitting unit in the client computer device A database search execution unit that obtains the new search result record group by executing a corresponding new search; and a database that is transmitted by the search request transmission unit in the client computer device by referring to the database update history table unit. Was done Deletion record information extraction means for extracting information corresponding to records in the database deleted after the search date and time as the deletion record information; and transmitting the search request for the new search result record group and the deletion record information. A client / server type database search system, comprising: a search result returning means for returning to a client computer device. 4. A client-server type database search system having a function of caching database search results and executing a search process on a database held by a server computer device in accordance with a search request from a client computer device. The server computer device comprising: a database update history table means for recording a history of changed, added, or deleted records in the database; and the client computer device by referring to the database update history table means. By executing a new search corresponding to the search request transmitted from the client computer only for records in the database changed or added after the search date and time transmitted from the client computer A database search execution unit for acquiring a new search result record group; and information corresponding to a record in the database deleted after the search date and time transmitted from the client computer device by referring to the database update history table unit. Record information extracting means for extracting the new search result record group and the delete record information to the client computer device that transmitted the search request. Server computer device. 5. A client / server type database search system having a function of caching a search result of a database and executing a search process on a database held by a server computer in accordance with a search request from a client computer. The client computer device to be configured, wherein a search result cache means for storing, as cache data, a search condition, a search date and time, and a search result record group corresponding thereto for a database in the server computer device; A cache data search unit for searching for cache data having the same search condition as the search condition of the search request in the search result cache unit; and a search date and time in the searched cache data for the search request. A search request transmitting unit that transmits both to the server computer device; and a search result record group in the cache data searched by the cache data search unit for an entry of a record corresponding to the deleted record information returned from the server computer device. Cache data deleting means for deleting a search result record group returned from the server computer device and a search result record group in the cache data from which the deletion has been executed; A cache data update unit that saves the search condition of the request, a new search date and the combined search result record group as new cache data in the search result cache unit, and stores the combined search result record group in the search result record unit. Search results for search requests And a search result output means for outputting as a search result. 6. A storage medium which is read out when used by a computer, wherein a search condition for the database, a search date and time, and a search result record group corresponding thereto are stored in a search result cache device as cache data. And a function of recording the history of changed, added, or deleted records in the database as a database update history table.When a search request is issued, in the search result cache device, the search condition of the search request A function of searching for cache data having the same search condition, and by referring to the database update history table, for a record in the database changed or added after the search date and time in the searched cache data. Only new search corresponding to the search request A function T for executing a record entry corresponding to a record in the database deleted after the search date and time from a search result record group in the searched cache data by referring to the database update history table. A function of combining a group of records newly searched from the database with a group of search result records in the cache data where the deletion has been executed; a search condition of the search request, a new search date and time, A function of re-storing the combined search result record group as new cache data in the search result cache device, and a function of outputting the combined search result record group as a search result for the search request. A computer-readable storage medium to be executed by a computer. 7. A storage medium which is read when used by a server computer device which holds a database and executes a search process on the database in accordance with a search request from a client computer device, wherein the storage medium is modified in the database. , A function of recording the history of the added or deleted records as a database update history table, by referring to the database update history table, changed or added after the search date and time transmitted from the client computer device A function of acquiring a new search result record group by executing a new search corresponding to the search request transmitted from the client computer device only for records in the database, and referring to the database update history table. A function for extracting information corresponding to a record in the database deleted after the search date and time transmitted from the client computer device as deleted record information, the new search result record group and the deleted record information And a function for returning the search request to the client computer device that has transmitted the search request, and a computer-readable storage medium for causing the server computer device to perform the function. 8. A storage medium which is read out when used by a client computer which issues a search request to a server computer which holds a database, comprising: a search condition and a search date and time for the database in the server computer; And a search result record group corresponding to them in a search result cache device as cache data, and, when the search request is issued, the same search condition as the search condition of the search request in the search result cache device. A function of transmitting the search request to the server computer together with the search date and time in the searched cache data; and a record corresponding to the deleted record information returned from the server computer. Entry A function of deleting from the search result record group in the searched cache data, and combining the new search result record group returned from the server computer device with the search result record group in the deleted cache data. A function of re-storing the search condition of the search request, a new search date and the combined search result record group as new cache data in the search result cache device, and a function of the combined search result record. A computer-readable storage medium for causing the client computer device to perform a function of outputting a group as a search result in response to the search request.