Database Management Systems

Abstract

To provide a database management system that can efficiently handle quasi-dynamic data and quasi-static data necessary for automatic driving of a vehicle.SOLUTION: A database management system includes a hierarchical database and retrieval means. A local edge network includes a mobile base station and a mobile body. The hierarchical database has a main database, an intermediate database connected to the main database and arranged in the mobile base station, and an end database of the mobile body. Sensor information acquired by a sensor of the mobile body is stored in the end database of the mobile body as registration data. A replication of the registration data is stored in the intermediate database. The intermediate database and the end database have a local master table for specifying a database where registration data in the local edge network exists. The retrieval means specifies a database in which required registration data is stored based on the local master table.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a database management system. [Background technology]

[0002] In recent years, safe driving and autonomous driving assistance for vehicles are becoming more practical, and autonomous driving is also being developed. In these systems, for example, high-precision map information required for the system is distributed from the cloud to the vehicle via a mobile base station, so it is realized as a communication system that combines an on-board computer and communication. This data is stored in databases owned by the mobile base station and the vehicle.

[0003] In safe vehicle driving, autonomous driving assistance, and autonomous driving, data known as dynamic maps are used that overlay constantly changing information required for advanced safe driving assistance and autonomous driving, such as information on surrounding vehicles, pedestrians, and traffic signals, accident information, and traffic regulation information, on static map data for car navigation systems that is collected, edited, and distributed once every few months to several years by dedicated data collection vehicles.

[0004] In autonomous driving of vehicles, control is mainly based on information in the vicinity of the vehicle, so the information that changes from time to time in the dynamic map is often data on a relatively small local area. In addition, in order to obtain a dynamic map with higher accuracy, i.e., with a larger amount of information, it is effective to expand the data by sharing the information acquired by a mobile body moving in a local area with other mobile bodies. Focusing on vehicle 1, the vehicle searches for and acquires the required information from a database distributed in a network owned by other mobile bodies.

[0005] A search method using a response accumulation device has been proposed as a method for efficiently searching database resources distributed over a network and efficiently searching for data with high evaluation value without placing a heavy load on the network or database (see JP 2000-235583 A). In the above search method, a search process is first performed on a database located in a small area, and the response data accumulated in the response accumulation device, i.e., the number of valid pieces of information, is counted by a response counter. Then, if it is determined that a predetermined number of response data cannot be obtained from this small area, a search is performed in a wider range from the search device via a communication device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-235583 A Summary of the Invention [Problem to be solved by the invention]

[0007] For example, in the case of an autonomous vehicle, if there is a fallen object on the road in the direction of travel of the vehicle, information about the fallen object is information that the vehicle must obtain before reaching the fallen object. Although it depends on the distance between the vehicle and the fallen object, the allowable time for searching for information is thought to be about tens of milliseconds to tens of minutes. Data with an allowable delivery delay time of tens of milliseconds to tens of minutes is called quasi-dynamic data or quasi-static data depending on the allowable time.

[0008] In the above-mentioned conventional search method using a response accumulation device, if the required information is not present in the database of the moving vehicle itself, it is necessary to search for information on other vehicles or mobile base stations, which requires a search via a network. If there are many searches via a network, the time required for the search will increase dramatically, and there is a risk that the above-mentioned allowable time will not be met.

[0009] The present invention has been made in light of the above circumstances, and has an object to provide a database management system that can efficiently handle quasi-dynamic data and quasi-static data necessary for automatic driving of vehicles and the like. [Means for solving the problem]

[0010] A database management system according to one aspect of the present invention is a database management system installed in a communication system having one or more local edge networks and a cloud data center, the database management system comprising a hierarchical database and a search means, the local edge networks each including one or more mobile base stations and a plurality of moving objects connected to each other via a common wireless interface, the cloud data center configured to be able to communicate with at least one of the mobile base stations, the hierarchical database comprising one main database disposed in the cloud data center, an intermediate database directly or indirectly connected to the main database and disposed in the mobile base station, and a search means connected to the intermediate database and disposed in the moving object. and an end database, wherein the mobile body has a sensor, and sensor information acquired by the sensor is stored in the end database located on the mobile body having the sensor as registration data of the hierarchical database, and a copy of the registration data stored in the end database is stored in at least one of the intermediate databases of the local edge network to which the mobile body belongs, the intermediate database and the end database have a local master table including information identifying the database in which the registration data exists in the local edge network to which they belong, and the search means identifies the intermediate database and the end database in which the registration data required by a mobile body is stored based on the local master table. Effect of the Invention

[0011] The database management system of the present invention can efficiently handle registered data, particularly semi-dynamic data and semi-static data required for automatic driving of vehicles. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic configuration diagram showing a database management system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of a communication system in which the database management system of FIG. 1 is used. [Diagram 3] FIG. 3 is a schematic configuration diagram showing the local edge network of FIG. [Figure 4] FIG. 4 is a schematic diagram showing the data structure of a hierarchical database in the database management system of FIG. [Diagram 5] FIG. 5 is an image showing map data corresponding to a road network. [Figure 6] FIG. 6 is a schematic data diagram showing an example of the local master table. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Description of the embodiment of the present invention] First, the embodiments of the present invention will be listed and described.

[0014] A database management system according to one aspect of the present invention is a database management system installed in a communication system having one or more local edge networks and a cloud data center, the database management system comprising a hierarchical database and a search means, the local edge networks each including one or more mobile base stations and a plurality of moving objects connected to each other via a common wireless interface, the cloud data center configured to be able to communicate with at least one of the mobile base stations, the hierarchical database comprising one main database disposed in the cloud data center, an intermediate database directly or indirectly connected to the main database and disposed in the mobile base station, and a search means connected to the intermediate database and disposed in the moving object. and an end database, wherein the mobile body has a sensor, and sensor information acquired by the sensor is stored in the end database located on the mobile body having the sensor as registration data of the hierarchical database, and a copy of the registration data stored in the end database is stored in at least one of the intermediate databases of the local edge network to which the mobile body belongs, the intermediate database and the end database have a local master table including information identifying the database in which the registration data exists in the local edge network to which they belong, and the search means identifies the intermediate database and the end database in which the registration data required by a mobile body is stored based on the local master table.

[0015] Since the database management system uses a local master table, when the search means identifies the intermediate database and the end database in which the registration data required by one mobile body is stored, there is no need to access a cloud data center. Moreover, in the database management system, one or more mobile base stations and multiple mobile bodies are connected to each other via a common wireless interface, so the intermediate database and the end database can be accessed without going through a cloud data center or a mobile base station. Furthermore, in the database management system, a copy of the registration data based on the sensor information acquired by the sensor of the mobile body is present at least in the intermediate database 20 of the mobile base station 110. Therefore, either the end database in which the registration data to be acquired exists or the intermediate database may be accessed. With the above configuration, the database management system can access the registration data required by one mobile body in a short time, so that the registration data, particularly the quasi-dynamic data and quasi-static data required for automatic driving of a vehicle, can be efficiently handled.

[0016] The intermediate database and the terminal database preferably have a data table for storing the registration data of the intermediate database or the terminal database identified by the search means. By providing the intermediate database and the terminal database with the above-mentioned data table in this way, the registration data required for each mobile unit or mobile base station can be selectively copied to this data table, thereby reducing the amount of access via the network and further improving efficiency.

[0017] The main database may have an overall master table including information for identifying a database in which the registered data of the entire one or more local edge networks exists. By providing the main database with the overall master table in this manner, it becomes easier to optimize the local master table. Furthermore, when there are multiple local edge networks, searches can be efficiently performed across the local edge networks.

[0018] The system may further include a communication speed estimation means for estimating communication speeds between the intermediate database and the terminal database identified by the search means, the sensor information may include metadata for estimating the communication speeds, and the communication speed estimation means may estimate the communication speeds based on the metadata. By estimating the communication speeds in this manner using the communication speed estimation means, it is possible to access the required registered data in a shorter time.

[0019] The metadata may include at least one of the location, speed, radio wave shielding degree, communication traffic, and actual communication result speed of the one mobile unit. By including at least one of the location, speed, radio wave shielding degree, communication traffic, and actual communication result speed of the one mobile unit in the metadata, the estimation accuracy of the communication speed can be improved.

[0020] The database management system may be particularly suitable for use in a system including a vehicle.

[0021] [Details of the embodiment of the present invention] Hereinafter, a database management system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0022] The database management system 1 shown in FIG. 1 includes a hierarchical database 1a, a search unit 1b, and a communication speed estimation unit 1c.

[0023] 2, the database management system 1 is installed in a communication system including one or more local edge networks 100 and a cloud data center 200. The communication system in which the database management system 1 is used will be described below.

[0024] [Local Edge Network] 3, each local edge network 100 includes one or more mobile base stations 110 and multiple moving objects 120 connected to each other via a common wireless interface. The local edge network 100 may also include a roadside unit 130.

[0025] The mobile base station 110, the multiple moving objects 120, and the roadside device 130 are connected via a wireless interface. As the wireless interface, 5G, local 5G, 4G, DSRC (Dedicated Short Range Communications), LPWA (Low Power Wide Area), WiFi, IEEE802.11 series, ITS (Intelligent Transport System) communication interfaces, etc. can be used.

[0026] Moreover, the mobile base station 110 and the multiple moving objects 120 are connected to each other via a common wireless interface. That is, the mobile base station 110 and the multiple moving objects 120 can directly communicate with each other. Furthermore, communication can be performed using one or multiple moving objects 120 as a repeater, such as a vehicle 121-drone 122-mobile base station 110. Note that in FIG. 3, in order to avoid cluttering the drawing, only a part of the communication between the above two objects is shown, and not all of the communication is shown.

[0027] <Mobile base station> The mobile base station 110 is a base station that manages and controls the geographical area in which wireless communication is possible in the local edge network 100. Specifically, the mobile base station 110 performs data management processing and distribution control processing for multiple moving objects 120, for example.

[0028] The mobile base stations 110 include a main base station 111 and a local base station 112, and can communicate with mobile base stations 110 in other local edge networks 100 or with a cloud data center 200, forming a communications backbone network.

[0029] (Main base station) The main base station 111 supervises and controls the entire geographical range. The main base station 111 has a communication function, an intermediate database 20, and a processor. The main base station 111 may also have a sensor. By having the sensor in this way, information acquired by the main base station 111 can be used as dynamic data.

[0030] (Local base station) The local base station 112 belongs to a lower layer than the main base station 111, and subdivides and controls the geographical area controlled by the main base station 111. For this reason, a plurality of local base stations 112 are usually provided. Conversely, if there is no need to subdivide the above geographical area, the local base station 112 can be omitted, and the mobile base station 110 is composed only of the main base station 111, and directly controls the entire above geographical area.

[0031] The local base station 112 has a communication function, an intermediate database 20, and a processor. The local base station 112 may also have a sensor. By having the local base station 112 have the sensor in this way, information acquired by the local base station 112 can be used as dynamic data. The local base station 112 can be, for example, a local 5G base station.

[0032] <Mobile object> The multiple mobile entities 120 are devices that move within a data sharing area (a geographical area in which wireless communication can be performed) managed by the local edge network 100.

[0033] The multiple moving bodies 120 may include a vehicle 121, a drone 122, a mobile robot 123, a portable device 124, a bicycle 125, and the like. Of these, it is preferable that the moving body 120 includes a vehicle 121. The database management system 1 can be particularly suitably used in a system including the vehicle 121, for example, a V2X communication system used in automatic driving and MaaS business. "V2X" is an abbreviation for Vehicle to X, and is a technology that collectively refers to the connection and mutual cooperation between the vehicle 121 and something (other vehicles 121, pedestrians, infrastructure, networks, etc.). This V2X is essential for, for example, automatic driving of the vehicle 121. In the V2X communication system, it is necessary to handle time series data having a large dynamic range in time and space acquired by the vehicle 121. The database management system 1 can particularly efficiently handle such time series data. The following description is based on the assumption that the moving object 120 includes a vehicle 121, but this does not mean that the database management system 1 requires the vehicle 121 to be a necessary component of the moving object 120.

[0034] The multiple moving bodies 120 each have a communication function, a terminal database 30, a processor, and a sensor 120a. Note that a "sensor" refers to an element or device that detects a phenomenon in the real world and converts the detected phenomenon into a signal that can be processed by a computer. In FIG. 1, the drone 122 is shown having the sensor 120a, but the other moving bodies 120 also have the sensor 120a, although they are not shown in the figure.

[0035] The mobile objects 120 are connected to each other, and the information collected by the sensors 120a of each mobile object is processed by the processor and stored in the terminal database 30. The information may include any natural phenomenon such as weather and temperature, phenomena caused by man-made objects such as traffic congestion, human vital information such as heart rate, respiratory rate, blood pressure, etc., information on people approaching the vehicle, information on objects fallen on the road, time, moving speed, position, and other information that can be detected by a sensor. In the database management system 1, for example, camera images taken by a mobile robot 123, map data for driving, photographed data taken by a drone 122, and 3D shape data generated therefrom are assumed.

[0036] <Roadside unit> The roadside device 130 is installed on a road and is a device that controls and monitors the traffic of the vehicles 121. The roadside device 130 includes traffic lights, street lights, etc., and is connected to the local base station 112 via the wireless interface.

[0037] The roadside unit 130 has a communication function. In addition, the roadside unit 130 preferably has a database (the intermediate database 20 or the terminal database 30), a processor, and a sensor. By having these configurations, the information acquired by the roadside unit 130 can be used as dynamic data.

[0038] Furthermore, the roadside unit 130 may have a function as the mobile base station 110. In other words, the roadside unit 130 can function as a stationary mobile unit 120, a mobile base station 110, or both.

[0039] [Cloud Data Center] The cloud data center 200 includes a router 210, a server 220, and a main database 10. The cloud data center 200 is configured to be able to communicate with at least one mobile base station 110.

[0040] Cloud data center 200 collects information from mobile base stations 110 in each data sharing area via router 210. Server 220 manages the collected information, and main database 10 stores the information under the control of server 220. Note that the information stored in main database 10 is necessary information among the information collected and processed by mobile base stations 110. Not all data is necessarily stored.

[0041] [Communication Systems] As shown in FIG. 2, a plurality of local edge networks 100 are installed according to the geographical range (data sharing area) in which wireless communication is possible, covering a wide area.

[0042] In the network configuration shown in Fig. 2, first, in the local edge network 100, a sensor 120a of a mobile unit 120 acquires information, which is processed by the mobile unit 120 and stored in an end database 30 of the mobile unit 120. A part of the above information, that is, information regarding which mobile unit 120 acquired what information, is collected by a local base station 112 included in a mobile base station 110 together with information acquired by a roadside unit 130. After all the collected information is processed by the local base station 112, it is further collected and processed by a main base station 111, and the necessary information is appropriately relayed to a cloud data center 200 using the main base station 111 as a gateway (GW).

[0043] [Hierarchical Database] As already mentioned, the mobile base station 110, the mobile body 120, etc. have the intermediate database 20 and the end database 30, but from the perspective of the hierarchical database 1a, the hierarchical database 1a has one main database 10 located in the cloud data center 200, an intermediate database 20 connected directly or indirectly to the main database 10 and located in the mobile base station 110, and an end database 30 connected to the intermediate database 20 and located in the mobile body 120.

[0044] <Registered data> In the database management system 1, sensor information acquired by a sensor 120a of a moving object 120 is stored as registered data of a hierarchical database 1a in a terminal database 30 disposed in the moving object 120 having the sensor 120a.

[0045] In addition, in the database management system 1, a copy of the above-mentioned registration data stored in the end database 30 is stored in at least one intermediate database 20 of the local edge network 100 to which the mobile unit 120 belongs. Specifically, for example, the local base station 112 periodically checks the end database 30 of the mobile unit 120 within the geographical range it governs, and when new registration data within the geographical range it governs is registered in the end database 30, it copies the registration data to its own intermediate database 20. Similarly, the main base station 111 periodically checks the intermediate databases 20 of the multiple local base stations 112, and when new registration data is registered in the intermediate database 20, it copies the registration data to its own intermediate database 20. Note that this is just an example, and other methods may be used.

[0046] The mobile unit 120 may stop and be powered off. Alternatively, the mobile unit 120 may move outside the geographical range governed by one local edge network 100. In such a case, other mobile units 120 may not be able to access the terminal database 30 of this mobile unit 120 through the local edge network 100, and may not be able to obtain the necessary registered data. In the database management system 1, a copy of the above registered data is stored in the intermediate database 20, which is in principle always in operation, so that the necessary registered data can be obtained in principle at all times.

[0047] Furthermore, in the database management system 1, other mobile entities 120 may have copies of the above-mentioned registered data. This will be described in detail later.

[0048] In the database management system 1, the search means 1b identifies the intermediate database 20 and the end database 30 in which registration data required by one mobile object 120 is stored, based on a local master table 50 described later (see FIG. 4). The intermediate database 20 and the end database 30 preferably have a data table 40 that stores the registration data of the intermediate database 20 or the end database 30 identified by the search means 1b.

[0049] The data table 40 will be described with reference to Fig. 4. Fig. 4 shows one local base station 112 included in the local edge network 100 and a plurality of vehicles 121 (five vehicles in Fig. 4) controlled by this local base station 112. For simplification, the terminal databases 30 (first terminal database 31 and second terminal database 32, respectively) for two of the five vehicles 121 (first vehicle 121a and second vehicle 121b) are shown. The local base station 112 also has an intermediate database 20.

[0050] For example, if the search means 1b identifies the intermediate database 20 of the local base station 112 as the database storing the registration data a required by the first vehicle 121a, the registration data a is stored in the data table 40 of the first vehicle 121a. On the other hand, if the second vehicle 121b does not require the registration data a, the registration data a is not stored in the data table 40 of the second vehicle 121b.

[0051] The data table 40 also stores sensor information acquired by the sensor 120a of the vehicle 121. The data table 40 of the intermediate database 20 also stores a copy of the above-mentioned registered data stored in the terminal database 30.

[0052] In the data table 40 in which the registration data is stored in this manner, the stored registration data differs between the local base station 112 and the multiple vehicles 121. That is, for example, there exists registration data a stored only in the first vehicle 121a and the local base station 112, registration data b stored only in the second vehicle 121b and the local base station 112, registration data c stored in all, registration data d stored only in the first vehicle 121a and the second vehicle 121b, etc. Hereinafter, in order to distinguish between the three data tables 40 shown in Fig. 4, the data tables 40 of the first vehicle 121a and the second vehicle 121b may be referred to as the first data table 41 and the second data table 42, respectively.

[0053] By having the intermediate database 20 and the terminal database 30 have the above-mentioned data table 40 in this way, the registration data required for each moving body 120 or mobile base station 110 can be selectively copied to this data table 40, thereby reducing the amount of access via the network and further improving efficiency.

[0054] <Local master table> As shown in FIG. 4, the database management system 1 has a local master table 50 including information for identifying the database in which the intermediate database 20 and the end database 30 in the local edge network 100 to which the intermediate database 20 and the end database 30 belong, in which the registration data exists. The local master table 50 has the same information in the intermediate database 20 and the end database 30 in the local edge network 100. Specifically, for example, when new registration data is stored in the end database 30 in each mobile unit 120, the information is collected in the main base station 111 via the local base station 112 or directly. The main base station 111 updates the local master table 50 and distributes the updated local master table 50 to the intermediate database 20 and the end database 30 in the local edge network 100. In this way, the identity of the local master table 50 is ensured. Alternatively, when new registration data is stored in the mobile unit 120, the information can be shared among the mobile units 120, including other mobile units 120, by using a communication means that allows sharing at the same time.

[0055] A specific example of the local master table 50 will be described below, taking as an example a case where the subject of sensor information is a "falling object." For "falling object" information, it is advisable to label the data to link it to a road (road link, see FIG. 5), and update the information for each road link. For example, in FIG. 5, the first vehicle 121a (label V1) is traveling between a0 and a1 (road link a01). Note that a similar configuration can be used for sensor information other than that of a fallen object.

[0056] FIG. 6 is an example of a local master table 50 corresponding to this road link a01. In FIG. 6, time* (* is a number) indicates the time when the data was updated. After that, the second column separated by " / " is the label of the vehicle 121 etc. for which the fallen object data was updated, the third column indicates the position and speed of the vehicle 121 (although it is written in km in FIG. 6, it means km / h), and the fourth column indicates the vehicle 121 etc. that stores the corresponding registered data. Note that "φ" means that there is no change. Also, by using GPS as the sensor 120a for the position, and by using the speedometer of the vehicle 121 for the speed, it is possible to obtain sensor information.

[0057] For example, record R1 at time1 indicates that at time1, a first vehicle 121a with label V1 obtained registration data of a fallen object while traveling at a speed of 20 km / h at a position 10 m away, and that only V1 has this registration data at the stage of time time1. Record R2 at time time2 indicates that at time time2, a local base station 112 with label B1 duplicated the above registration data, and that the above registration data is held by V1 and B1. At time time3 (record R3), a vehicle 121 with label V3 passed by the same location and discovered the same fallen object, so that the above registration data is held by V1, V3, and B1. These three are linked because they are for the same fallen object.

[0058] When a new fallen object is found on the road link a01, it is registered as a new record as shown in record R4 at time time4. This record R4 indicates that the object is shared with V4 at the same time as it is registered by V1. This registered data is also deleted at time time5 (record R5) by making the vehicles 121 etc. that have the registered data into an empty set (number 0). By deleting unnecessary data in this way, it is possible to prevent the data table 40 and the local master table 50 from becoming too large, and to handle the registered data more efficiently. Examples of registered data to be deleted include data that has been there for a certain amount of time, data that has not been rediscovered even though multiple vehicles 121 have passed through the same place, etc.

[0059] Record R6 at time time6 indicates that there was no particular change when the first vehicle 121a with label V1 passed, meaning that there was no new discovery. At the same time, it can also be data for grasping the position and speed of V1 at time time6.

[0060] <Overall master table> In the database management system 1, the main database 10 of the cloud data center 200 has an overall master table that includes information for identifying the database in which the above-mentioned registered data of the entire one or more local edge networks 100 exists.

[0061] The above-mentioned overall master table is a collection of records of the local master tables 50 of each local edge network 100.

[0062] Although the local master table 50 of each local edge network 100 is updated successively, it is not necessary to update the overall master table every time there is an update to each local master table 50. For example, it may be updated periodically at a relatively long interval.

[0063] The server 220 of the cloud data center 200 may optimize this overall master table. That is, the server 220 resolves inconsistencies within one local master table 50 or between multiple local master tables 50, erases old registered data, corrects duplicate registrations, and so on. The optimized overall master table is divided into local master tables 50 corresponding to each local edge network 100 and transmitted to each local edge network 100. Each local edge network 100 updates the local master table 50 in each local edge network 100 based on the information of the received local master table 50.

[0064] Also, the mobile unit 120 can use it to obtain information on the adjacent local edge network 100 in advance when moving to the adjacent local edge network 100. Using only the local master table 50, only the local edge network 100 to which the mobile unit 120 belongs can be searched, but using the overall master table makes it possible to search for information on the adjacent local edge networks 100.

[0065] [Search methods] The search means 1b identifies the intermediate database 20 and the end database 30 in which the registration data required by one mobile entity 120 is stored, based on the local master table 50 as described above.

[0066] For example, assume that the second vehicle 121b with the label V2 in Fig. 5 is planning to pass through the road link a01 in the future. At this time, for the second vehicle 121b, the fallen object information on the road link a01 corresponds to the required registered data.

[0067] The search means 1b uses the processor of the second vehicle 121b to refer to the local master table 50 of the second vehicle 121b. In the case of the local master table 50 shown in Fig. 6, it can be seen that there is a fallen object at a position of 10 m from record R3 of time3, and it can be determined that the registered data is stored in three databases, V1, V3 and B1, that is, two terminal databases 30 and one intermediate database 20. On the other hand, it can be seen that there is no longer an object at a position of 30 m from record R5 of time5, and that there is no change in the position of 50 m from record R6 of time6.

[0068] In the database management system 1, the above-mentioned search is performed by using the processor of the second vehicle 121b and referring to the local master table 50 of the second vehicle 121b, so there is no need to search via a network. Therefore, it is possible to quickly identify the intermediate database 20 and the end database 30 in which the registration data is stored without imposing a load on the network.

[0069] The second vehicle 121b can obtain the required registration data by accessing either the identified intermediate database 20 or the end database 30 (in this case, the end databases 30 of V1 and V3 and the intermediate database 20 of B1). Which database to access can be determined by using the communication speed estimation means 1c.

[0070] [Communication speed estimation means] The communication speed estimation means 1c estimates the communication speed with the intermediate database 20 and the end database 30 identified by the search means 1b.

[0071] The sensor information acquired by the sensor 120a of the mobile unit 120 includes metadata for estimating the communication speed, and the communication speed estimation means 1c is configured to estimate the communication speed based on the metadata.

[0072] The metadata preferably includes at least one of the location, speed, radio wave shielding degree, communication traffic, and speed of actual communication result of the one mobile unit 120. For example, the local master table 50 in Fig. 6 includes the location and speed (direction and speed) of the mobile unit 120. When the location of the mobile unit 120 is used, it is preferable to also use the location of the mobile base station 110.

[0073] In the local edge network 100 of the communication system in which the database management system 1 is used, there is a path for acquiring registered data by communication between terminal databases 30, i.e., between mobile units 120 directly without going through a mobile base station 110. In this case, the distance to the mobile unit 120 with which the communication is to be performed, the speed, radio wave shielding degree, communication traffic, and the communication speed of the actual communication result change from moment to moment, and the communication speed may change due to these. Therefore, by including at least one of the position, speed, radio wave shielding degree, communication traffic, and the communication speed of the actual communication result of the mobile unit 120 in the metadata in this way, the accuracy of estimating the communication speed can be improved.

[0074] Then, the communication speed estimation means 1c accesses the database that is estimated to have a faster communication speed to obtain the required registered data. By estimating the communication speed using the communication speed estimation means 1c in this manner, it becomes possible to access the required registered data in an even shorter time.

[0075] <Advantages> Since the database management system 1 uses the local master table 50, when the search means 1b specifies the intermediate database 20 and the end database 30 in which the registration data required by one mobile unit 120 is stored, there is no need to access the cloud data center 200. Furthermore, in the database management system 1, one or more mobile base stations 110 and multiple mobile units 120 are connected to each other via a common wireless interface, so the intermediate database 20 and the end database 30 can be accessed without going through the cloud data center 200 or the mobile base station 110. Furthermore, in the database management system 1, a copy of the registration data based on the sensor information acquired by the sensor 120a of the mobile unit 120 exists at least in the intermediate database 20 of the mobile base station 110. Therefore, it is possible to access either the end database 30 or the intermediate database 20 of the mobile unit 120 in which the registration data to be acquired exists. With the above configuration, the database management system 1 can access the registration data required by one mobile unit 120 in a short time, so that the registration data, particularly the quasi-dynamic data and quasi-static data required for the automatic driving of the vehicle 121, can be efficiently handled.

[0076] [Other embodiments] The above-mentioned embodiment does not limit the configuration of the present invention. Therefore, the above-mentioned embodiment may omit, replace or add components of each part of the above-mentioned embodiment based on the description in this specification and common general technical knowledge, and it should be understood that all of these are within the scope of the present invention.

[0077] In the above embodiment, the intermediate database and the end database have a data table that stores the registered data of the intermediate database or the end database specified by the search means, but the data table is not an essential component, and the present invention can achieve the same effect even if it is omitted. However, each time registered data is required, the specified database is accessed and the registered data is obtained. For this reason, it is preferable to have the above data table.

[0078] In the above embodiment, the main database has an overall master table including information for identifying a database in which registered data for one or more local edge networks exists, but the overall master table is not a required component and can be omitted. The present invention can achieve a certain effect even when it is operated only within a local edge network.

[0079] In the above embodiment, the case where the search means includes a communication speed estimation means for estimating the communication speed between the search means and the specified intermediate database and the end database has been described, but the communication speed estimation means is not an essential component and can be omitted. For example, the search means may access the specified intermediate database and the end database in a preset order until the registered data is obtained.

[0080] In the above embodiment, the case where the local base station deletes the registered data has been described, but it is not a necessary component for the local base station to delete the registered data. Instead of the local base station, the main base station, the cloud data center, or the mobile body may delete the registered data, or multiple base stations may delete the registered data. [Industrial Applicability]

[0081] As described above, the database management system of the present invention can efficiently handle registered data, particularly semi-dynamic data and semi-static data necessary for automatic driving of vehicles. [Explanation of symbols]

[0082] 1 Database Management Systems 1a Hierarchical Database 1b Search methods 1c Communication speed estimation means 10 Primary Database 20 Intermediate Database 30 Terminal Database 31 First Terminal Database 32 Second Terminal Database 40 Data Tables 41 First Data Table 42 Second Data Table 50 Local Master Table 100 Local Edge Network 110 Mobile base station 111 Main base station 112 Local base station 120 Mobile 120a Sensor 121 vehicles 121a 1st car 121b 2nd car 122 Drone 123 Mobile Robot 124 Mobile Phone 125 Bicycle 130 Roadside unit 200 Cloud Data Centers 210 Router 220 Server R1, R2, R3, R4, R5, R6 records

Claims

1. A database management system installed in a communication system including one or more local edge networks and a cloud data center, A hierarchical database and a search means are provided, Each of the local edge networks includes one or more mobile base stations and a plurality of mobile units connected to each other via a common wireless interface; the cloud data center is configured to be in communication with at least one of the mobile base stations; The hierarchical database is A primary database located in the cloud data center; an intermediate database located at said mobile base station and connected directly or indirectly to said main database; a terminal database connected to the intermediate database and located in the mobile unit; having The moving object has a sensor, The sensor information acquired by the sensor is stored as registration data of the hierarchical database in the terminal database disposed in the mobile body having the sensor, A copy of the registration data stored in the end database is stored in at least one of the intermediate databases of a local edge network to which the mobile unit belongs; The intermediate database and the terminal database each have a local master table including information for identifying a database in the local edge network to which the intermediate database and the terminal database belong in which the registration data exists; A database management system in which the search means identifies an intermediate database and a terminal database in which registration data required by one mobile object is stored based on the local master table.

2. 2. A database management system according to claim 1, wherein said intermediate database and said terminal database have a data table for storing registered data of the intermediate database or terminal database specified by said search means.

3. 3. A database management system according to claim 1, wherein said primary database comprises an overall master table containing information identifying databases in which said registration data resides for the entire one or more local edge networks.

4. a communication speed estimation means for estimating a communication speed between the intermediate database and the terminal database specified by the search means, the sensor information includes metadata for estimating the communication speed; 4. The database management system according to claim 1, wherein said communication speed estimating means estimates said communication speed based on said metadata.

5. 5. The database management system according to claim 4, wherein said metadata includes at least one of the location, speed, radio wave shielding degree, communication traffic, and speed of actual communication results of said one mobile unit.

6. 6. The database management system according to claim 1, wherein the moving object includes a vehicle.

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