WO2012032921A1

WO2012032921A1 - Data cache device, data cache method and program

Info

Publication number: WO2012032921A1
Application number: PCT/JP2011/068819
Authority: WO
Inventors: 陽介高野
Original assignee: 日本電気株式会社
Priority date: 2010-09-08
Filing date: 2011-08-16
Publication date: 2012-03-15
Also published as: JPWO2012032921A1

Abstract

Provided is a cache device capable of achieving a sufficient hit rate and impartiality by reflecting access behavior based on the content of a data object. The data cache device is provided with a storage means for storing a plurality of first data items; and a priority determining means for determining on the basis of the content of each of the plurality of first data items a priority for deleting the first data items from the storage means for each first data item.

Description

Data cache device, data cache method and program

The present invention relates to a data cache device, a data cache method, and a program, and more particularly to selection of a data item to be rejected due to addition of a new data item.

It is common to use a data cache that holds data objects acquired from a remote server system or the like via a network for later use. For example, most WEB browsers improve the responsiveness of the browser by holding the acquired data object as a local file for a certain period and reusing the same data object from the cache when requested.
Another example is a car navigation system that does not store map data in the device in recent years, and obtains only necessary map data via a network from a service such as Google (registered trademark) map, in order to be realized at low cost. The device appears. In this case as well, map data is generally held in a cache in order to improve display responsiveness.
On the other hand, since the device has only a finite area (memory, disk, etc.) to hold the data cache, it can reject data objects that are not expected to be used in the future and use them as a new cache. Reserve space.
In rejecting, it is first necessary to positively leave data objects that are predicted to be accessed in the future in the cache (improvement in hit rate). Furthermore, it is necessary to avoid a situation where a large area of the cache is consumed only by a specific data object and other data caches cannot be accommodated in the cache (realization of fairness).
As a method for improving the hit rate, there is a method in which the access frequency is the lowest and the access time is the oldest (LRU: Last Recently Used) as a rejection candidate (Patent Document 1).
On the other hand, the technique of Patent Document 2 applies different discard strategies by classifying data objects acquired and cached via a network according to size. This technology uses a method for limiting the proportion of a cache that a single data object can occupy when other data objects exist in the cache based on LRU for small to medium files. For data objects that are larger than the entire cache, the technique uses a method of setting a dedicated area that is small but not subject to LRU evaluation.
Patent Document 3 discloses an apparatus that determines a WEB page on which information is to be collected based on the degree of association between the contents of the WEB page and the collection target. Patent Document 4 discloses a map display method that summarizes and displays a narrow area when the position of an automobile approaches a destination.

Japanese Patent Laid-Open No. 2003-330792 Japanese Patent Laid-Open No. 08-115241 JP 2006-235729 A WO2005 / 020186

The techniques disclosed in Patent Documents 1 and 2 determine the rejection from the cache only based on the past external state (access frequency, access time, etc.) of the data object. For this reason, this technique cannot reflect the access behavior based on the contents of the data object, and cannot achieve a sufficient hit rate and fairness. The technologies disclosed in Patent Documents 3 and 4 are technologies that are not related to the cache and do not solve this problem.
An object of the present invention is to provide a data cache device, a data cache method, and a program that solve the above-described problems.

A data cache device according to an embodiment of the present invention includes storage means for storing a plurality of first data items;
Based on the contents of each of the plurality of first data items, there is provided priority determining means for determining a priority for rejecting the first data item from the storage means for each first data item.
A data cache method according to an embodiment of the present invention stores a plurality of first data items in an accumulation unit,
Based on the contents of each of the plurality of first data items, a priority for rejecting the first data item from the storage means is determined corresponding to each first data item.
A program according to an embodiment of the present invention includes a storage process in which a plurality of first data items are stored in a storage unit included in the computer.
Based on the contents of each of the plurality of first data items, a priority determination process is executed for determining a priority for rejecting the first data item from the storage unit corresponding to each first data item.

The present invention can improve the hit rate and fairness of cached data in a data cache device or the like.

The structure of the data cache apparatus 20 of 1st Embodiment is shown. The information which the storage part 14 of 1st Embodiment memorize | stores is shown. 4 is an operation flowchart of data access of the data cache device 20. 4 is an operation flowchart of the priority calculation unit 16. The structure of the data cache apparatus 20 of 2nd Embodiment is shown. The information which the storage part 14 of 2nd Embodiment memorize | stores is shown. The structure of the data cache apparatus 20 of 3rd Embodiment is shown.

<First Embodiment>
FIG. 1 shows the configuration of the data cache device 20 of this embodiment. The data cache device 20 of the present embodiment is, for example, an in-vehicle map display device such as a car navigation device that is loaded on an automobile or the like and displays a map.
The data cache device 20 includes a storage unit 14 that temporarily stores data items 40 and a priority calculation unit 16 that determines the priority 43 of rejection (deletion) of the data items 40 stored in the storage unit 14. .
The priority 43 is determined based on at least one of the distance N, the summarization degree M, and the consumption speed V of the data item 40 acquired based on the content of the data item 40 (data content 41).
The priority calculation unit 16 includes at least one of the distance income unit 17, the summary level acquisition unit 18, and the consumption speed acquisition unit 19. Each of the distance income unit 17, the summary level acquisition unit 18, and the consumption rate acquisition unit 19 acquires the distance N, the summary level M, and the consumption rate V of the data item 40 stored in the storage unit 14.
The distance N is the number of data items 40 between the data item 40 that is the starting point (for example, the data item 40 currently in use) and the data item 40 when the data content 41 of the data item 40 is provided to the user. Represents whether to provide the data content 41. The data cache device 20 makes it difficult for the data item 40 having a small distance N to be rejected from the storage unit 14 because it is likely to be necessary in the near future.
The summarization degree M represents the size of the number of information units (for example, the number of articles in a news page or the like, a product posted in a pamphlet) included in the data content 41 of the data item 40. The data cache device 20 makes it difficult for the data item 40 with a high summarization level M to be rejected from the storage unit 14 as an index, table of contents, portal use, etc. to a large amount of information is assumed.
The consumption speed V represents the speed at which the data content 41 held by the data item 40 is consumed by the user. The data cache device 20 makes it difficult for the data item 40 with a low consumption speed V to be rejected from the storage unit 14 because it is highly likely that the user will need it again.
Specific examples and calculation methods of the priority 43, the distance N, the summarization degree M, and the consumption speed V will be described later.
The data cache device 20 may include an input unit 10, an output unit 11, a control unit 12, an acquisition unit 13, and a rejection unit 15.
The input unit 10 is a keypad for inputting an instruction from a user, a GPS (Global Positioning System) device for measuring the position of an automobile or the like on which the data cache device 20 is mounted. The output unit 11 is a display device or the like. The touch sensor panel may function as the input unit 10 and the output unit 11.
For example, the control unit 12 determines the position and scale of the map to be displayed based on the information input from the input unit 10, acquires map data from the acquisition unit 13, and outputs the map data to the output unit 11. At this time, the control part 12 memorize | stores the identification information of the data item 40 currently output.
The acquisition unit 13 inputs map data at a position and scale instructed from the control unit 12 from the data supply device 30, outputs the map data to the control unit 12, and stores (caches) the data in the storage unit 14 to prepare for reuse. The data supply device 30 is, for example, a reading device such as a CD-ROM or DVD-ROM storing map data. The data supply device 30 may be a map data providing service server connected via a network.
The rejection unit 15 rejects the data items 40 from the storage unit 14 in descending order of priority 43 when the storage unit 14 is full.
Here, the storage unit 14 is a semiconductor memory or the like. The priority calculation unit 16, the control unit 12, the acquisition unit 13, and the rejection unit 15 are configured by hardware such as a logic circuit. All or part of the priority calculation unit 16, the control unit 12, the acquisition unit 13, and the rejection unit 15 may be realized by the processor of the data cache device 20 being a computer executing a program on a memory (not shown). good.
FIG. 2 shows information stored in the storage unit 14. The storage unit 14 can store a plurality of data items 40. The size of each data item 40 may be constant or variable. The number of data items 40 that can be stored in the storage unit 14 is determined by the storage capacity of the storage unit 14.
Each data item 40 includes data content 41, incidental information 42, priority 43, and access time 44.
The data content 41 is, for example, map data read from the data supply device 30. The size of the data content 41 is determined by the specifications of the data storage device 30 and information input from the input unit 10.
The incidental information 42 is information regarding the data content 41. The incidental information 42 is, for example, the latitude / longitude range and scale of the map data of the data content 41. The distance income part 17, the summarization degree acquisition part 18, and the consumption speed acquisition part 19 acquire the distance N, the summarization degree M, and the consumption speed V of this data item 40 based on this information, for example.
The access time 44 stores the time when the data acquisition unit 13 last accessed the data item 40.
The supplementary information 42, the priority 43, and the access time 44 may be stored in a storage device other than the storage unit 14 in association with the data content 41.
FIG. 3 is an operation flowchart of data access of the data cache device 20.
First, the control unit 12 receives a data request from the input unit 10, specifies the position and scale, and requests the acquisition unit 13 for map data (S1).
The data request includes, for example, the position and scale explicitly entered by the user from the keypad. The data request may include, for example, a current position input from the GPS device and a scale input from the keypad in the past. When the data cache device 20 is a car navigation device, the control unit 12 may input only the current position, calculate the distance from the destination, and calculate the scale according to the distance.
The acquisition unit 13 checks whether the data content 41 of the requested position and scale is already stored in the storage unit 14 (S2). The check may use the incidental information 42 or may use another existing data cache technology.
If already stored (Y in S2), the acquisition unit 13 outputs the data content 41 to the output unit 11 via the control unit 12 (S9), and the priority 43 and access time 44 of the data item 40 are displayed. Update (S10), the operation is terminated. The priority 43 is updated to the lowest priority, for example. The priority 43 may not be updated.
When the data content 41 of the requested position and scale is not stored in the storage unit 14 (N in S2), the acquisition unit 13 designates the position range and scale including the requested position, and stores the map data as data. It inputs from the supply apparatus 30 (S3), and outputs it to the output part 11 via the control part 12 (S4). The size of the position range is specified by a system parameter given to the data cache device 20, for example.
When there is free space in the storage unit 14 (Y in S5), the acquisition unit 13 stores the read data content 41 in the storage unit 14 and sets the priority 43 and the access time 44 (S7). The priority 43 is set, for example, to the lowest priority as an initial value.
Thereafter, the acquisition unit 13 stores the position range and scale output to the data supply device 30 in the incidental information 42 (S8), and ends the operation.
When there is no free space in the storage unit 14 (N in S5), the rejection unit 15 that has received a request from the acquisition unit 13 rejects the data item 40 having the lowest priority 43 from the storage unit 14 (S6).
FIG. 4 is an operation flowchart of the priority calculation unit 16. This operation is performed in parallel with the data access of FIG. 3, for example. This operation may be performed as a process preceding the data rejection (S6 in FIG. 3).
The priority calculation unit 16 selects a predetermined number of data items 40 from the data items 40 stored in the storage unit 14 from the oldest access time 44 (A1). At this time, the priority calculation unit 16 selects the data item 40 so that the data amount of the selected data item 40 group is larger than the data amount to be rejected (predetermined value or data to be added).
The priority calculation unit 16 performs the processing from step A3 to step A6 for each of the selected data items 40 (A2).
First, the priority calculation unit 16 uses the distance acquisition unit 17 to obtain the distance N between the data item 40 currently output to the output unit 11 and the data item 40 (A3). The distance acquisition unit 17 obtains the data item 40 currently output to the output unit 11 from the control unit 12.
When the map data is divided by a rectangular mesh of a certain distance, the distance acquisition unit 17 starts from one of the latitude and longitude ranges stored in the incidental information 42 of the two data items 40 before reaching the other. The number of meshes that pass through is obtained, and the number is output as the distance N.
The distance acquisition unit 17 may approximately calculate the distance N as follows. The distance acquisition unit 17 calculates, for example, the distance between the center points of the latitude / longitude range stored in the incidental information 42 of the two data items 40 or the distance between two adjacent points of the two ranges. The distance acquisition unit 17 outputs the number obtained by dividing the calculated distance by a predetermined unit distance according to the scale as the distance N.
That is, the distance N is a value that increases as the latitude / longitude range stored in the incidental information 42 of the two data items 40 increases.
Next, the priority calculation unit 16 uses the summarization level acquisition unit 18 to obtain the summarization level M of the data item 40 (A4). The summarization level acquisition unit 18 calculates, for example, from the scale stored in the incidental information 42 of the data item 40.
The summarization level acquisition unit 18 sets the summarization level M of map data having the largest scale stored in the data supply device 30 to 1, and the summation level M of map data having a smaller scale than that is a multiple thereof. For example, when the summarization level M of a 1/1000 map is 1, the summarization level of a 1/10000 map is 10.
That is, the summarization degree M is a value that increases as the scale stored in the incidental information 42 of the data item 40 decreases (the number of included administrative units increases).
Next, the priority calculation part 16 calculates | requires the consumption speed V of the said data item 40 using the consumption speed acquisition part 19 (A5). The consumption speed acquisition unit 19 calculates, for example, the scale stored in the incidental information 42 of the data item 40 and the speed of the automobile or the like in which the data cache device 20 is mounted.
The consumption speed acquisition unit 19 may obtain the speed of the car or the like from a speed measuring device such as the car or the control unit 12. For example, the control unit 12 continuously inputs position information from the GPS device that is the input unit 10, measures the speed of the automobile or the like in which the data cache device 20 is mounted, and outputs the measured speed to the consumption speed acquisition unit 19.
For example, the consumption speed acquisition unit 19 sets 1/1000 = 0.001 as the consumption speed V when the speed at which the automobile moves through the entire width of the map data having the summarization level M of 1 is 1000 seconds.
That is, the consumption speed V is a value that increases as the time for which the user needs the data content 41 of the data item 40 is shorter.
The priority calculation unit 16 determines the priority 43 of the data item 40 based on the obtained distance N, summarization M, and consumption speed V, and stores the priority 43 in the storage unit 14 (A6). The importance 43 is calculated so as to be higher (easily rejected) as the distance N is larger, the summarization M is smaller, and the consumption speed V is larger.
For example, the priority calculation unit 16 sets priority 43 = distance N × consumption speed V ÷ summarization M. In this case, the priority 43 increases as the value increases. The priority calculation unit 16 may employ a calculation method that increases as the value decreases.
The priority 43 may be determined based on only one of the distance N, the summarization degree M, the consumption speed V, or a combination of any two.
The data cache device 20 of this embodiment can improve the hit rate and fairness of cached map data.
The reason is that the priority calculation unit 16 calculates the priority 43 to be rejected from the storage unit 14 based on the position and scale of each map data.
<Second Embodiment>
FIG. 5 shows the configuration of the data cache device 20 of the second embodiment. The data cache device 20 of the present embodiment is, for example, a computer or a mobile terminal device that displays an electronic document such as a web page (hereinafter, web page). The data cache device 20 of the present embodiment is different from the first embodiment in the points described below. Other points are the same as in the first embodiment.
The input unit 10 may be a keypad or the like, or may be a keyboard or a mouse. The data supply device 30 is a Web page storage device such as a Web server connected to the data cache device 20 via the network 50 or the like.
The data cache device 20 of this embodiment may include a profile storage unit 1A. The profile storage unit 1A is a storage device such as a semiconductor memory or a disk device. The profile storage unit 1A includes, for example, a user's Web page usage speed (reading speed: the number of characters read per unit time, etc.) for each Web page content type (for example, a genre such as a novel or academic book). . These values are stored in the profile storage unit 1A by the user based on past experience and actual measurement.
FIG. 6 shows information stored in the storage unit 14 of the second embodiment. The incidental information 42 is described, for example, by an address (hereinafter referred to as URL) such as a URL (Uniform Resource Locator) where the data content 41 which is a Web page is stored, and a URL to another Web page included in the data content 41 Link information.
The incidental information 42 may be the number of information units included in the data content 41. The information unit is, for example, each news article in a newspaper, and is an explanatory description for each product in a product pamphlet.
The incidental information 42 may be the type of the data content 41 and the number of characters included in the data content 41.
An operation flowchart of data access of the data cache device 20 of this embodiment is also shown in FIG. In the following, description will be made focusing on the parts that are different from the first embodiment.
First, the control unit 12 receives a data request from the input unit 10, specifies a URL, and requests a web page from the acquisition unit 13 (S1). The data request includes, for example, a URL that the user explicitly inputs from a keyboard or the like.
The acquisition unit 13 checks whether the data content 41 of the requested URL is already stored in the storage unit 14 (S2).
When the data content 41 of the requested URL is not stored in the storage unit 14 (N in S2), the acquisition unit 13 designates the requested URL and inputs a Web page from the data supply device 30 ( S3), and output to the output unit 11 via the control unit 12 (S4).
When there is free space in the storage unit 14 (Y in S5), the acquisition unit 13 stores the read data content 41 in the storage unit 14 and sets the priority 43 and the access time 44 (S7). Thereafter, the acquisition unit 13 stores the incidental information 42 (S8) and ends the operation.
For example, the acquisition unit 13 acquires and stores the incidental information 42 as follows.
1) “URL where the data content 41 is stored” (own URL) is the URL output to the URL data supply device 30.
2) The “link information included in the data content 41” is extracted by the acquisition unit 13 using an HTML (Hypertext Markup Language) tag of the data content 41 as a key or by scanning text.
3) “Number of information units” is acquired from the HTML description of the data content 41. This number of information units is assumed to be described in advance in HTML by the creator of the Web page. Or the acquisition part 13 may extract and acquire a news headline from the text of the data content 41, using words, such as a communication company name, and a specific phrase as a key. The acquisition unit 13 may acquire the attribute of the Web page from the data supply device 30.
4) The “Web page type” is acquired from the HTML description by the acquisition unit 13. This type is described in advance in HTML by the creator of the Web page. Or the acquisition part 13 may scan the text of the data content 41, and may estimate from the style of a sentence, the frequency of generated words, etc. The acquisition unit 13 may acquire the attribute of the Web page from the data supply device 30.
5) The “number of characters on the Web page” is acquired by the acquisition unit 13 by scanning the text of the data content 41.
An operation flowchart of the priority calculation unit 16 of the present embodiment is also shown in FIG. Hereafter, the part which is different from 1st Embodiment is demonstrated.
The priority calculation unit 16 uses the distance acquisition unit 17 to obtain the distance N between the data item 40 currently output to the output unit 11 and the data item 40 (A3). In the present embodiment, it is assumed that the distance is N when the data item 40 currently output to the output unit 11 can be reached by following N links from the data item 40.
The distance acquisition unit 17 sequentially traces the other data items 40 from the “link information included in the data content 41” stored in the incidental information 42 of the data item 40 currently output to the output unit 11, The number of links until the data item 40 is reached is acquired.
The distance acquisition unit 17 may create a tree structure of links having reverse links in advance in a storage area (not shown) for efficient processing.
Next, the priority calculation unit 16 uses the summarization level acquisition unit 18 to obtain the summarization level M of the data item 40 (A4). The summarization level acquisition unit 18 sets the “number of information units” stored in the incidental information 42 of the data item 40 as the summarization level M, for example.
Next, the priority calculation part 16 calculates | requires the consumption speed V of the said data item 40 using the consumption speed acquisition part 19 (A5). The consumption speed acquisition unit 19 includes, for example, the “type of web page” and the “number of characters of the web page” in the incidental information 42 of the data item 40, and the type of web page content stored in the profile storage unit 1A. It is obtained from the usage speed of the user's Web page for each.
For example, the summarization level acquisition unit 18 divides “the number of characters on the Web page” by the usage speed of the Web page corresponding to “Web page type” to obtain the usage time. If the usage time is 100 seconds, the summarization level acquisition unit 18 calculates the consumption speed V of the data item 40 per second as 1/100 = 0.01. The consumption speed V may be a fixed value for each “web page type”.
Further, the summary level M and the consumption speed V may be given as attributes for each Web page by the creator of each Web page and described in the HTML of each page.
In the above description, the data acquisition unit 13 extracts the supplementary information 42 from the data content 41 and stores it in the storage unit 14, but when obtaining the distance N, the summarization degree M, and the consumption speed V, The priority calculation unit 16 may extract equivalent information from the data content 41 or the like. In addition, the priority calculation unit 16 may determine the distance N, the summarization level M, and the consumption speed V by itself, and necessarily includes the distance income unit 17, the summarization level acquisition unit 18, and the consumption speed acquisition unit 19 individually. There is no need to be.
The data cache device 20 of the present embodiment can improve the hit rate and fairness of electronic documents such as Web pages to be cached.
The reason is that the priority calculation unit 16 calculates the priority 43 to be rejected from the storage unit 14 based on the link information of the electronic document, the number of included information units, the number of included characters, and the like.
<Third Embodiment>
The data cache device 20 of the third embodiment has the configuration of the data cache device 20 of the first and second embodiments. The data cache device 20 of the present embodiment is different from the first and second embodiments in the points described below. Other points are the same as those in the first or second embodiment.
The input unit 10 is a GPS device and a keypad. The input unit 10 may be a GPS device, a keyboard, a mouse, or the like. The data supply device 30 uses, for example, a CD-ROM reader or a DVD-ROM reader that stores map data, and a Web server connected via the network 50.
Accordingly, the storage unit 14 of the data cache device 20 of the present embodiment stores, for example, a mixture of map data and Web pages. The data cache device 20 of the present embodiment is, for example, a smartphone or a portable information terminal.
The data cache device 20 according to the present embodiment includes the contents of the storage supplementary information 42 according to whether the data item 40 is map data or a web page in S8 of FIG. 3 or A3 to A5 of FIG. The acquisition method of the distance N, the summarization degree M, and the consumption speed V is switched. If the data item 40 is map data, the data cache device 20 processes the same as in the second embodiment if it is a Web page, as in the first embodiment.
The data cache device 20 of this embodiment can improve the hit rate and fairness of various data to be cached. The reason is that the priority calculation unit 16 evaluates the internal state of the data item 40 using three scales of the distance N, the summarization degree M, and the consumption speed V, which do not depend on the type of the data item 40, and This is because the rejection priority 43 from the storage unit 14 is determined on the basis.
<Fourth Embodiment>
The data cache device 20 according to the present embodiment includes an accumulation unit 14 that stores a plurality of data items 40 and a priority calculation unit 16. The priority calculation unit 16 determines a priority 43 for rejecting the data item 40 from the storage unit 14 corresponding to each data item 40 based on the data contents 41 of each of the plurality of data items 40.
The data cache device 20 can improve the hit rate and fairness of the data items 40 to be cached. The reason is that the priority calculation unit 16 calculates the priority 43 to be rejected from the storage unit 14 based on the data content 41 of each data item 40.
Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
<Other expressions of the embodiment>
Although part or all of said embodiment and an Example may be described as follows, it is not restricted to the following.
(Appendix 1)
Storage means for storing a plurality of first data items;
A data cache device comprising priority determining means for determining a priority for rejecting the first data item from the storage means corresponding to each first data item based on the contents of each of the plurality of first data items.
(Appendix 2)
The priority determination means obtains a distance between the second data item and each of the plurality of first data items based on the content of the second data item and each of the plurality of first data items. The data cache device according to appendix 1, wherein the priority is increased as the distance is longer.
(Appendix 3)
The contents of the first and second data items are position-dependent data,
The data cache device according to appendix 2, wherein the priority determination means obtains the distance based on a position of the second data item and a position of each of the plurality of first data items.
(Appendix 4)
Each of the contents of the plurality of first data items is data linked directly from the contents of the second data item or via the contents of other first data items,
The data cache device according to appendix 2, wherein the priority determination means obtains, as the distance, the number of links through which the second data item reaches each of the plurality of first data items.
(Appendix 5)
Each of the plurality of first data items includes one or more information units;
The data cache device according to any one of appendices 1 to 4, wherein the priority determination means increases the priority as the number of information units included in the plurality of first data items decreases.
(Appendix 6)
Each of the plurality of first data items is map data;
The data cache device according to appendix 5, wherein the priority determination means increases the priority of the first data item as the scale is larger.
(Appendix 7)
The data cache device according to any one of appendices 1 to 6, wherein the priority determination means increases the priority as the consumption speed of the contents of each of the plurality of first data items increases.
(Appendix 8)
The data cache device according to appendix 8, wherein the priority determination means determines the priority based on a content type and a number of characters of each of the plurality of first data items.
(Appendix 9)
A storage process for storing a plurality of first data items in a storage means provided in the computer;
A program for executing a priority determination process for determining a priority for rejecting the first data item from the storage unit corresponding to each first data item based on the contents of each of the plurality of first data items.
(Appendix 10)
Based on the content of the second data item and the content of each of the plurality of first data items, the computer determines a distance between the second data item and each of the plurality of first data items, and the distance The program according to appendix 9, wherein the priority determination process is executed such that the longer the is, the higher the priority is.
(Appendix 11)
The contents of the first and second data items are position-dependent data,
The program according to appendix 10, wherein the computer executes the priority determination process for obtaining the distance based on a position of the second data item and a position of each of the plurality of first data items.
(Appendix 12)
Each of the contents of the plurality of first data items is data linked directly from the contents of the second data item or via the contents of other first data items,
The program according to appendix 10, wherein the computer executes the priority determination process for obtaining, as the distance, the number of links through which the second data item reaches each of the plurality of first data items.
(Appendix 13)
Each of the plurality of first data items includes one or more information units;
The program according to any one of appendices 9 to 12, which causes the computer to execute the priority determination process for increasing the priority as the number of information units included in the plurality of first data items decreases.
(Appendix 14)
Each of the plurality of first data items is map data;
The program according to appendix 13, wherein the computer executes the priority determination process for increasing the priority of the first data item as the scale is larger.
(Appendix 15)
The program according to any one of appendices 9 to 14, which causes the computer to execute the priority determination process for increasing the priority as the consumption speed of the contents of each of the plurality of first data items increases.
(Appendix 16)
The program according to supplementary note 15, which causes the computer to execute the priority determination process for determining the priority based on a content type and a number of characters of each of the plurality of first data items.
(Supplementary Note 17) A plurality of first data items are stored in the storage means,
A cache method for determining a priority for rejecting the first data item from the storage unit corresponding to each first data item based on the contents of each of the plurality of first data items.
(Appendix 18)
Based on the content of the second data item and the content of each of the plurality of first data items, the distance between the second data item and each of the plurality of first data items is determined, and the longer the distance, The cache method according to appendix 17, wherein the priority is increased.
(Appendix 19)
The contents of the first and second data items are position-dependent data,
The cache method according to appendix 18, wherein the distance is obtained based on a position of the second data item and a position of each of the plurality of first data items.
(Appendix 20)
Each of the contents of the plurality of first data items is data linked directly from the contents of the second data item or via the contents of other first data items,
The cache method according to appendix 18, wherein the distance from the second data item to the first data item is obtained as the distance.
(Appendix 21)
Each of the plurality of first data items includes one or more information units;
The cache method according to any one of appendices 17 to 20, wherein the priority is increased as the number of information units included in the plurality of first data items is smaller.
(Appendix 22)
Each of the plurality of first data items is map data;
The cache method according to appendix 21, wherein the priority of the first data item is increased as the scale is larger.
(Appendix 23)
The cache method according to any one of appendices 17 to 22, wherein the higher the consumption speed of the content of each of the plurality of first data items, the higher the priority.
(Appendix 24)
The cache method according to appendix 23, wherein the priority is determined based on a content type and a number of characters of each of the plurality of first data items.
This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2010-201088 for which it applied on September 8, 2010, and takes in those the indications of all here.

DESCRIPTION OF SYMBOLS 10 Input part 11 Output part 12 Control part 13 Acquisition part 14 Accumulation part 15 Rejection part 16 Priority calculation part 17 Distance acquisition part 18 Summarization degree acquisition part 19 Consumption speed acquisition part 1A Profile memory | storage part 20 Data cache apparatus 30 Data supply apparatus 40 Data item 41 Data content 42 Attached information 43 Priority 44 Access time 50 Network

Claims

Storage means for storing a plurality of first data items;
A data cache device comprising priority determining means for determining a priority for rejecting the first data item from the storage means corresponding to each first data item based on the contents of each of the plurality of first data items.
The priority determination means obtains a distance between the second data item and each of the plurality of first data items based on the content of the second data item and the contents of each of the plurality of first data items. The data cache device according to claim 1, wherein the priority is set higher as the distance is longer.
The contents of the first and second data items are position-dependent data,
3. The data cache device according to claim 2, wherein the priority determination unit obtains the distance based on a position of the second data item and a position of each of the plurality of first data items.
Each of the contents of the plurality of first data items is data linked directly from the contents of the second data item or via the contents of other first data items,
3. The data cache device according to claim 2, wherein the priority determination unit obtains, as the distance, the number of links through which the second data item reaches each of the plurality of first data items.
Each of the plurality of first data items includes one or more information units;
5. The data cache device according to claim 1, wherein the priority determination unit increases the priority as the number of information units included in the plurality of first data items decreases.
Each of the plurality of first data items is map data;
6. The data cache device according to claim 5, wherein the priority determination means increases the priority of the first data item as the scale is larger.
The data cache device according to any one of claims 1 to 6, wherein the priority determination means increases the priority as the consumption speed of the contents of the plurality of first data items increases.
The data cache device according to claim 8, wherein the priority determination means determines the priority based on a type and a number of characters of each content of the plurality of first data items.
A storage process for storing a plurality of first data items in a storage means provided in the computer;
A program for executing a priority determination process for determining a priority for rejecting the first data item from the storage unit corresponding to each first data item based on the contents of each of the plurality of first data items.
Storing a plurality of first data items in the storage means;
A cache method for determining a priority for rejecting the first data item from the storage unit corresponding to each first data item based on the contents of each of the plurality of first data items.