JP5706956B1 - Database system and database control method - Google Patents

Abstract

Access to data using a cache is speeded up while maintaining consistency of cached data.
A database system includes a plurality of cache servers and a cache data management device. The cache data management device has a table in which identification codes of data to be stored in the distributed database are associated with data to be cached by each cache server. When a query for data to be cached is received from the cache server, the cache data management device Then, a list of identification codes of data to be cached is transmitted as a response. When the cache server receives a request to store data in the distributed database from the client, the cache server determines whether the data included in the request is data to be cached in the server, and stores the data in the memory cache according to the determination result. And having a cache target determination unit for storing data in the distributed database.
[Selection] Figure 1

Description

  The present invention relates to a database system and a database control method.

  In order to speed up access to data stored in a distributed database, a cache that temporarily stores data is used (for example, Patent Document 1).

JP 2013-077063 A

  However, there is a problem that processing for maintaining data consistency becomes complicated when data stored in each database constituting the distributed database is updated in parallel.

  In view of the above circumstances, the present invention provides a database system and a database control method capable of speeding up access to data using a cache while maintaining the consistency of data stored in a distributed database with simple processing. The purpose is that.

  One aspect of the present invention includes a distributed database, a client that acquires and uses data stored in the distributed database, a plurality of cache servers that cache data to be stored in the distributed database, and a cache data management device. The cache data management device includes a table in which an identification code of data to be stored in the distributed database and data to be cached by each cache server are associated with each other from the client to the distributed database. When a query of a cache server to be used for accessing is received, a cache server corresponding to data used by the client among the plurality of cache servers is set as a first access destination, and the other cache servers are 2 is sent as a response to the query, and when a query for data to be cached is received from the cache server, a list of identification codes of the data to be cached is sent as a response based on the table. When the cache server receives a storage request for storing data in the distributed database from the client, the cache server determines whether or not the data included in the storage request is data to be cached in its own server. Accordingly, the data base system includes a cache target determination unit that stores the data in the memory cache and then stores the data in the distributed database.

  One aspect of the present invention is characterized in that, in the above-described database system, the cache target determination unit clears the data when a predetermined period has elapsed since the data was stored in the memory cache.

  In addition, according to one aspect of the present invention, in the above database system, when the client does not respond from the cache server indicated by the first access destination, the client passes through the cache server indicated by the second access destination. And accessing the distributed database.

  One embodiment of the present invention includes a distributed database, a client that acquires and uses data to be stored in the distributed database, a plurality of cache servers that cache data to be stored in the distributed database, and the distributed database. A database control method in a database system comprising: a cache data management device having a table in which an identification code of data to be stored and data to be cached by each cache server are associated with each other, wherein the cache data management device includes the client When a query for a cache server to be used for accessing the distributed database is received from the cache server, the cache server corresponding to the data used by the client among the plurality of cache servers is first accessed. And when the cache data management device receives an inquiry about data to be cached from the cache server, the first step of transmitting access information with the other cache server as a second access destination as a response to the inquiry. A second step of transmitting, as a response, a list of identification codes of data to be cached based on the table, and when the cache server receives an accumulation request for storing data in the distributed database from the client, It is determined whether or not the data included in the accumulation request is data to be cached in the local server, and the data is stored in the memory cache according to the determination result, and then stored in the distributed database. And a step characterized in that It is a database control method.

  According to the present invention, since the data to be cached by the cache server is limited, even when the client accesses the distributed database via another cache server, the same data is cached in a plurality of cache servers and is consistent. It is possible to prevent the sex from breaking. In the present invention, a cache data management device is provided, and the data stored in the distributed database and the cache server are temporarily stored in a simple process in which the client inquires the cache data management device of the access destination cache server. It is possible to speed up access to data using a cache server while maintaining consistency with the data.

It is a block diagram which shows the structural example of the database system in embodiment. It is a figure which shows an example of the process which memorize | stores base station information in the distributed database 2 in the database system of embodiment. It is a figure which shows an example of the process in which the base station information utilization apparatus 12 searches base station information in the database system of embodiment. It is a figure which shows an example of the process which memorize | stores base station information in the distributed database 2 in the database system of embodiment. It is a figure which shows an example of the process in which the base station information utilization apparatus 12 searches base station information in the database system of embodiment.

  Hereinafter, a database system and a database control method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of a database system in the embodiment. As shown in FIG. 1, the database system includes a plurality of base station information storage devices 11, a plurality of base station information utilization devices 12, a distributed database 2, a plurality of cache servers 3, and a cache data management device 4. . In the configuration example shown in FIG. 1, the database system has a configuration including one cache data management device 4, but a plurality of cache data management devices 4 may be provided to be redundant.

  In the configuration example shown in FIG. 1, the base station information storage device 11 and the base station information utilization device 12 as clients for the distributed database 2, the cache server 3, and the cache data management device 4 communicate via the network 5. Although a configuration in which the client and the cache server 3 are communicably connected is shown, a network that connects the client and the cache data management device 4 so that they can communicate with each other, and a cache server 3 A network that connects the cache data management device 4 in a communicable manner may exist individually.

  The plurality of base station information storage apparatuses 11 are provided corresponding to the determined areas. The base station information storage device 11 acquires the base station information of the area associated with the own device. The base station information storage device 11 stores the acquired base station information in the distributed database 2 via the cache server 3. The base station information includes an identification code that uniquely identifies the area corresponding to itself and the base station corresponding to itself.

  Similar to the base station information storage device 11, the plurality of base station information utilization devices 12 are provided corresponding to the determined areas. The base station information utilization apparatus 12 acquires base station information of an arbitrary region from the distributed database 2 via the cache server 3 based on the identification code. Based on the acquired base station information, the base station information utilization apparatus 12 generates control information used to control the base station in the area with which the base station information is associated, controls the base station, and the like.

  The distributed database 2 stores base station information in a plurality of areas acquired by a plurality of base station information storage apparatuses 11. The distributed database 2 has a plurality of databases 21 that store base station information in a plurality of regions. The base station information stored in the distributed database 2 is distributed and stored in any one of the plurality of databases 21 based on the access frequency, the update frequency, and the like.

  The plurality of databases 21 are communicably connected via the network 22. The database 21 itself stores the base station information or stores the base station information in another database 21 in response to the base station information accumulation request received from the cache server 3. Further, the database 21 transmits base station information stored therein as a response in response to a search request for base station information received from the cache server 3, or a base station device stored in another database 21. Is received from another database 21 and transferred.

  Each of the plurality of cache servers 3 is communicably connected to one of the databases 21 in the distributed database 2. The cache server 3 is provided for each region. The cache server 3 is uniquely assigned an address used for identifying and accessing each of the cache servers 3. The cache server 3 includes a cache target determination unit 31 and a memory cache 32. The cache target determination unit 31 receives cache target information including an identification code of base station information to be cached by its own server from the cache data management device 4 and stores it.

  The cache target determination unit 31 stores the base station information in the memory cache 32 of its own server based on the base station information and the cache target information included in the base station information storage request received from the base station information storage device 11. It is determined whether or not to make it. The cache target determination unit 31 stores the base station information received from the base station information storage device 11 in the memory cache 32 according to the determination result. In addition, the cache target determination unit 31 transmits a base station information storage request received from the base station information storage device 11 to the distributed database 2 and stores the base station information in the distributed database 2. When storing the base station information in the memory cache 32, the cache target determination unit 31 stores the base station information in association with the time when the base station information is stored in the memory cache 32.

  Further, when receiving the base station information search request received from the base station information utilization apparatus 12, the cache target determination unit 31 is included in the search request based on the identification code and the cache target information included in the search request. It is determined whether or not the base station information indicated by the identification code is a cache target. Further, when the base station information indicated by the identification code included in the search request is a cache target, the cache target determination unit 31 determines whether the base station information is stored in the memory cache 32. When the base station information that is the target of the search request is stored in the memory cache 32, the cache target determination unit 31 reads the base station information from the memory cache 32. The cache target determination unit 31 transmits the read base station information as a search result to the base station information utilization apparatus 12 that has transmitted the base station information search request.

  The cache target determination unit 31 receives the base station information requested by the received base station information search request if it is not a cache target in its own server, or if it is a cache target but is not stored in the memory cache 32. The base station information search request is transmitted to the distributed database 2. The cache target determination unit 31 receives base station information for a base station search request transmitted to the distributed database 2. The cache target determination unit 31 transmits the received base station information to the base station information utilization apparatus 12 that is the transmission source of the base station information search request.

  The cache data management device 4 has a table including a list of identification codes of base station information to be cached by the cache server 3 for each cache server 3 provided in the database system. When the cache data management device 4 receives an inquiry about base station information to be cached from the cache server 3, the cache data management device 4 reads a list of identification codes associated with the cache server 3 from the table. The cache data management device 4 transmits the read list of identification codes as cache target information to the cache server 3 that sent the inquiry.

  In addition, the cache data management device 4 receives a request from the base station information storage device 11 to query the cache server 3 to be accessed when the base station information is stored in the distributed database 2. This inquiry includes an identification code corresponding to the base station information. The cache data management device 4 uses a table to identify the cache server 3 associated with the identification code included in the received inquiry request, sets the address of the identified cache server 3 as the first access destination, The address of the server 3 is determined as the second access destination. The cache data management device 4 transmits access destination information including the first access destination and the second access destination to the base station information storage device 11 that is the transmission source of the inquiry.

  Further, the cache data management device 4 receives from the base station information utilization device 12 a request for querying the cache server 3 to be accessed when searching for the base station information in the distributed database 2. This inquiry includes base station information or an identification code corresponding to the region. The cache data management device 4 uses a table to identify the cache server 3 associated with the identification code included in the received inquiry request, sets the address of the identified cache server 3 as the first access destination, The address of the server 3 is determined as the second access destination. The cache data management device 4 transmits access destination information including the first access destination and the second access destination to the base station information utilization device 12 that is the transmission source of the inquiry.

  FIG. 2 is a diagram illustrating an example of processing for storing base station information in the distributed database 2 in the database system of the embodiment. In the example illustrated in FIG. 2, the database system includes two cache servers 3 (a cache server 3a and a cache server 3b). A case where the cache server 3a is associated with the base station information stored in the base station information storage apparatus 11 will be described.

  In the cache server 3a, the cache target determination unit 31 transmits a request for inquiring about base station information (cache target) to be cached by the server itself to the cache data management device 4 (step S11).

  The cache data management device 4 reads a list of identification codes indicating base station information to be cached by the cache server 3a that is the transmission source of the inquiry request from the table of the own device. The cache data management device 4 transmits the list of read identification codes as a reply to the inquiry request to the cache server 3a to notify the cache target (step S12). In the cache server 3a, the cache target determination unit 31 stores a list of identification codes notified from the cache data management device 4.

  In the cache server 3b, the cache target determination unit 31 transmits a request for inquiring about base station information (cache target) to be cached by the server itself to the cache data management device 4 (step S13).

  The cache data management device 4 reads a list of identification codes indicating base station information to be cached by the cache server 3b that is the transmission source of the inquiry request, from the table of the own device. The cache data management device 4 transmits the read identification code list to the cache server 3b as a reply to the inquiry request, and notifies the cache target (step S14). In the cache server 3b, the cache target determination unit 31 stores a list of identification codes notified from the cache data management device 4.

  The base station information storage device 11 transmits a request for inquiring of the cache server 3 to be accessed when the base station information acquired by the own device is stored in the distributed database 2 to the cache data management device 4 (step S15).

  The cache data management device 4 determines the first access destination (cache server 3a) and the second access destination (cache server 3b) based on the identification code of the base station information included in the inquiry request, and the first access Access information including the destination and the second access destination is transmitted to the base station information storage apparatus 11 as a reply to the inquiry request (step S16).

  The base station information storage device 11 stores the base station information stored in the distributed database 2 and the base station information in the first access destination (cache server 3a) included in the access information received from the cache data management device 4. A storage request including the request is transmitted (step S17).

  The cache server 3a receives a storage request from the base station information storage device 11. In the cache server 3a, the cache target determination unit 31 detects that the identification code of the base station information included in the received accumulation request is included in the stored identification code list. The cache target determining unit 31 determines that the base station information included in the received accumulation request is base station information to be cached, and stores the base station information in association with the current time in the memory cache 32 ( Step S18).

  When the cache target determination unit 31 stores the base station information in the memory cache 32, the cache target determination unit 31 transmits a storage request for storing the base station information in the distributed database 2 to the distributed database 2 (step S19).

  When receiving the storage completion notification from the distributed database 2 (step S20), the cache target determination unit 31 transmits the fact that the storage of the base station information is completed to the base station information storage device 11 that is the source of the storage request, The storage completion is notified (step S21).

  FIG. 3 is a diagram illustrating an example of processing in which the base station information utilization device 12 searches for base station information in the database system of the embodiment. In the example illustrated in FIG. 3, as in the example illustrated in FIG. 2, the database system includes two cache servers 3 (a cache server 3 a and a cache server 3 b). In addition, a case will be described in which the cache server 3a is associated with the base station information to be searched by the base station information utilization apparatus 12 and the base station information is stored in the memory cache 32 of the cache server 3a. Note that steps S11 to S14 in FIG. 3 are the same processes as steps S11 to S14 in FIG.

  The base station information utilization apparatus 12 transmits a request for inquiring the cache server 3 to be accessed when searching the base station information used by the own apparatus in the distributed database 2 to the cache data management apparatus 4 (step S31).

  The cache data management device 4 determines the first access destination and the second access destination based on the identification code of the base station information included in the inquiry request, and includes the first access destination and the second access destination. The access information is transmitted to the base station information utilization apparatus 12 as a reply to the inquiry request (step S32).

  The base station information utilization device 12 requests the first access destination (cache server 3a) included in the access information received from the cache data management device 4 to search for the identification code of the base station information to be used and the base station information. A search request to be transmitted is transmitted (step S33).

  The cache server 3a receives the search request from the base station information utilization device 12. In the cache server 3a, the cache target determination unit 31 detects that the identification code of the base station information included in the received search request is included in the list of stored identification codes. The cache target determining unit 31 determines that the base station information indicated by the received search request is base station information to be cached, and further detects that the base station information is stored in the memory cache 32. The cache target determining unit 31 reads base station information corresponding to the search request from the memory cache 32 (step S34).

  The cache target determination unit 31 transmits the read base station information as a search result to the base station information utilization apparatus 12 that is the transmission source of the search request (step S35).

  FIG. 4 is a diagram illustrating an example of processing for storing base station information in the distributed database 2 in the database system according to the embodiment. In the example illustrated in FIG. 4, as in the example illustrated in FIG. 2, the database system includes two cache servers 3 (cache server 3 a and cache server 3 b). Further, the cache server 3a is associated with the base station information to be searched by the base station information utilization apparatus 12. In the example illustrated in FIG. 4, a case will be described in which the base station information storage device 11 and the cache server 3a are unable to communicate due to a failure in the network 5. Note that steps S11 to S16 in FIG. 4 are the same processes as steps S11 to S16 in FIG.

  The base station information storage device 11 stores the base station information stored in the distributed database 2 and the base station information in the first access destination (cache server 3a) included in the access information received from the cache data management device 4. A storage request including the request is transmitted (step S41).

  The base station information storage device 11 determines that a failure has occurred in the network 5 or the cache server 3a because a response to the storage request cannot be obtained from the cache server 3a. The base station information storage device 11 transmits a storage request including base station information to be stored in the distributed database 2 and a request to store the base station information to the second access destination (cache server 3b) included in the access information. (Step S42).

  The cache server 3b receives a storage request from the base station information storage device 11. In the cache server 3b, the cache target determination unit 31 detects that the identification code of the base station information included in the received accumulation request is not included in the list of stored identification codes. The cache target determining unit 31 determines that the base station information included in the received accumulation request is not base station information to be cached, and transmits a storage request for storing the base station information in the distributed database 2 to the distributed database 2 ( Step S43).

  When the cache target determination unit 31 receives the storage completion notification from the distributed database 2 (step S44), the cache target determination unit 31 transmits that the storage of the base station information is completed to the base station information storage device 11 that is the transmission source of the storage request, The storage completion is notified (step S45).

  In the cache server 3a, the cache target determination unit 31 has passed a certain period since the base station information was stored in the memory cache 32 based on the time associated with the base station information stored in the memory cache 32. It is determined whether or not. When it is determined that the fixed period has elapsed, the cache target determining unit 31 clears (deletes) the base station information that has been stored for a fixed period from the memory cache 32 (step S46).

  FIG. 5 is a diagram illustrating an example of processing in which the base station information utilization apparatus 12 searches for base station information in the database system according to the embodiment. In the example illustrated in FIG. 5, as in the example illustrated in FIG. 2, the database system includes two cache servers 3 (a cache server 3 a and a cache server 3 b). Further, the cache server 3a is associated with the base station information to be searched by the base station information utilization apparatus 12. In the example illustrated in FIG. 5, a case will be described in which the base station information utilization device 12 and the cache server 3a are unable to communicate due to a failure in the network 5. Note that steps S11 to S14 and steps S31 to S32 in FIG. 5 are the same processes as steps S11 to S14 and steps S31 to S32 in FIG.

  The base station information utilization device 12 requests the first access destination (cache server 3a) included in the access information received from the cache data management device 4 to search for the identification code of the base station information to be used and the base station information. A search request to be transmitted is transmitted (step S51).

  The base station information utilization apparatus 12 determines that a failure has occurred in the network 5 or the cache server 3a because a response to the search request cannot be obtained from the cache server 3a. The base station information utilization device 12 transmits to the second access destination (cache server 3b) included in the access information, an identification code of the base station information to be used and a search request for requesting a search for the base station information (step). S52).

  The cache server 3b receives the search request from the base station information utilization device 12. In the cache server 3b, the cache target determining unit 31 detects that the identification code of the base station information included in the received search request is not included in the list of stored identification codes. The cache target determining unit 31 determines that the base station information indicated by the received search request is not base station information to be cached, and transmits the search request to the distributed database 2 (step S53).

  When the cache target determination unit 31 receives the base station information indicated by the search request from the distributed database 2 as a search result (step S54), the cache target determination unit 31 transmits the search result to the base station information utilization apparatus 12 that has transmitted the search request ( Step S55).

  4 and 5, the processing when the base station information storage device 11 and the base station information utilization device 12 cannot access the cache server 3a due to a failure of the network 5 has been described. However, a failure occurs in the cache server 3a. The same processing is performed even if it is down. When the cache server 3a is down, the memory cache 32 is not cleared in step S46 in FIG.

  According to the database system of the embodiment, when the cache server 3 that should cache certain base station information is stopped, the client (base station information storage device 11 and base station information utilization device 12) is the second access destination. The distributed database 2 is accessed via the other cache server 3 shown. At this time, the other cache servers 3 do not store in the memory cache 32 other than the base station information that the server itself should cache. This prevents the base station information that is not updated from remaining in the other cache server 3 after the cache server 3 to cache a certain base station information is restored, and the old base stored in the other cache server 3 by the client It is possible to prevent the station information from being acquired.

  Further, according to the database system of the embodiment, the cache server 3 receives the new storage request (update request) for a certain period of time for the base station information stored in the memory cache 32. Clear base station information as invalid information. Thus, the distributed database 2 is not connected via the cache server 3 indicated by the second access destination, but the cache server 3 that caches the base station information in which the base station information storage device 11 is located due to a failure (for example, disconnection) of the network 5. , The mismatch between the base station information in the distributed database 2 and the base station information cached by the cache server 3 can be resolved.

  In order to take advantage of the availability of the distributed database, when the memory cache is arranged at each node of the distributed database so that it does not become a single point of failure, the distributed database can be updated from any node, so the distributed database from various locations The data of is updated. In this case, the consistency between the data in the memory cache and the data in the distributed database is lost. On the other hand, in the database system of the present embodiment, the base station information to be cached in the cache server 3 is limited, so that the base station information cached in the cache server 3 and the distributed database 2 are stored. It is possible to prevent the consistency with the base station information from being lost and to accumulate and search the reliable base station information at high speed. In the database system of the present embodiment, the client of the base station information storage device 11 and the base station information utilization device 12 makes a simple process in which the cache data management device 4 is inquired about the access destination cache server 3, and in the distributed database 2. While maintaining data consistency, it is possible to speed up access to data using a cache server.

  Further, the base station information cached by the cache server 3 is limited, and the cache base station information is provided with an expiration date for a certain period, so that the cache server 3 can be stopped or communicated to the cache server 3. Even if the cache server 3 is restored after the base station information is stored in the distributed database 2 via another cache server 3 when a failure occurs, the consistency between the memory cache 32 and the distributed database 2 is maintained. Can keep.

  In addition, since the memory cache 32 is cleared when there is no base station information storage request from the base station information storage device 11 for a certain period of time, communication between the client and the cache server 3 performing the cache operation due to the network 5 or the like being down Even if the communication between the client and the cache server 3 that performs caching is restored after the client makes a request to store the base station information to the other cache server 3, the cache server 3 Can prevent the old base station information from being returned to the client when the search request is received.

  Any or all of the base station information storage device 11, the base station information utilization device 12, the cache server 3, and the cache data management device 4 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” is a program that dynamically holds a program for a short time, like a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be realized using hardware such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  It can also be applied to applications where speeding up with a memory cache is essential while maintaining the availability of a distributed database.

DESCRIPTION OF SYMBOLS 11 ... Base station information storage apparatus 12 ... Base station information utilization apparatus 2 ... Distributed database 21 ... Database 22 ... Network 3, 3a, 3b ... Cache server 31 ... Cache object determination part 32 ... Memory cache 4 ... Cache data management apparatus 5 ... network

Claims (4)

A database system comprising: a distributed database; a client that acquires and uses data stored in the distributed database; a plurality of cache servers that cache data stored in the distributed database; and a cache data management device,
The cache data management device includes:
A table associating identification codes of data to be stored in the distributed database with data to be cached by the cache servers;
When receiving an inquiry of a cache server used when accessing the distributed database from the client, a cache server corresponding to data used by the client among the plurality of cache servers is set as a first access destination, Sending access information with the cache server as the second access destination as a response to the inquiry;
When a query for data to be cached is received from the cache server, a list of identification codes of data to be cached is transmitted as a response based on the table,
The cache server is
When a storage request for storing data in the distributed database is received from the client, it is determined whether the data included in the storage request is included in the list transmitted to its own server, and the data is included in the list. If included , store the data in the memory cache and then store the data in the distributed database.If the data is not included in the list, store the data in the distributed database without storing the data in the memory cache. database system characterized by having a cache object determination unit Ru is stored the data. The database system according to claim 1,
The cache target determination unit
A database system, wherein a predetermined period of time elapses after data is stored in the memory cache, and the data is cleared. In the database system according to claim 1 or 2,
The client
When there is no response from the cache server indicated by the first access destination, the distributed database is accessed via the cache server indicated by the second access destination. A distributed database; a client that acquires and uses data stored in the distributed database; a plurality of cache servers that cache data stored in the distributed database; an identification code of data stored in the distributed database; and the cache A database control method in a database system comprising a cache data management device having a table that associates data to be cached by each server,
When the cache data management apparatus receives an inquiry from a cache server used when accessing the distributed database from the client, a cache server corresponding to data used by the client among the plurality of cache servers is first selected. A first step of transmitting, as a response to the query, access information having the other access destination as the second access destination;
A second step of transmitting, as a response, a list of identification codes of data to be cached based on the table when the cache data management device receives a query of data to be cached from the cache server;
When the cache server receives a storage request for storing data from the client in the distributed database, the cache server determines whether the data included in the storage request is included in the list, and the data is included in the list. If the data is stored in the memory cache after the data is stored in the memory cache and the data is not included in the list, the data is stored in the distributed database without storing the data in the memory cache. database control method characterized by including a third step of Ru is stored.

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