JP2018142807A - Distributed DB system and timer setting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately set a timer value for timeout.SOLUTION: A capture server 10 of a distributed DB system 100 measures a delay time of communication performed between each DB server 20 and each of other DB servers, and stores the measured delay time in a capture log storage unit 13a. Then, the capture server 10 classifies delay times stored in the capture log storage unit 13a by between each DB server 20 and each of other DB servers, and calculates an average and a variance of delay times between each DB server 20 and each of other DB servers. Next, the capture server 10 determines a timer value set for the delay time of communication performed between each DB server 20 and each of other DB servers using the calculated average and variance of the delay time between each DB server 20 and each of other DB servers.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a distributed DB system and a timer setting method.

  Conventionally, in a distributed DB system that relays between a plurality of DB servers in response to a request from a DB client, it is common to install the DB server at a remote location so that the entire system does not stop. In such a distributed DB system, since a communication network is used for relaying between DB servers, the relay time between DB servers is affected by the communication distance, the configuration of the NW device, and the like, and varies depending on the communication path.

  Further, in such a distributed DB system, a timer value is set as a time limit until a DB client makes a request and receives a response to the request. Become.

JP 2014-239331 A JP-A-4-208791

  However, the conventional technique has a problem that the timeout timer value may not be set appropriately. In other words, in the conventional technology, for example, there is a complexity in the timer design when a new distributed DB system is introduced or when a DB server is additionally arranged. In the distributed DB system, since the DB server is arranged at a distant distance and there is an influence of the communication distance, the configuration of the network device, etc., the communication speed by the relay differs depending on the communication path, so the timer considering the communication path It may be difficult to set the value appropriately.

  In order to solve the above-described problems and achieve the object, the distributed DB system of the present invention is a distributed DB system in which each DB server installed in a different place communicates with each other. Measuring the delay time of the communication, and storing the measured delay time in the storage unit, classifying the delay time stored in the storage unit for each DB server, the average of the delay time between each DB server And a timer that is set for each delay time of communication performed between the DB servers using the average and variance of the delay times between the DB servers calculated by the calculation unit. And a determining unit that determines a value.

  The timer setting method of the present invention is a timer setting method executed by a distributed DB system that communicates with each other DB servers installed at different locations, and a delay time of communication performed between the DB servers. And measuring the delay time stored in the storage unit, classifying the delay time stored in the storage unit for each DB server, and calculating the average and variance of the delay time between each DB server A determination step for determining a timer value to be set for each delay time of communication performed between the DB servers using the calculation step and the average and variance of the delay times between the DB servers calculated by the calculation step And a process.

  According to the present invention, it is possible to appropriately set a timeout timer value.

FIG. 1 is a diagram illustrating an example of a configuration of a distributed DB system according to the first embodiment. FIG. 2 is a diagram for explaining the delay time in the distributed DB system according to the first embodiment. FIG. 3 is a block diagram showing the configuration of the capture server according to the first embodiment. FIG. 4 is a diagram illustrating an example of information stored in the capture log storage unit. FIG. 5 is a diagram illustrating a process for measuring the delay time. FIG. 6 is a diagram for explaining processing for notifying each DB server of a timer value. FIG. 7 is a flowchart for explaining processing by the capture server according to the first embodiment. FIG. 8 is a block diagram showing a configuration of a capture server according to the second embodiment. FIG. 9 is a diagram for explaining a series of timer setting processes by the capture server according to the second embodiment. FIG. 10 is a flowchart for explaining processing by the capture server according to the second embodiment. FIG. 11 is a diagram illustrating a computer that executes a timer setting program.

  Embodiments of a distributed DB system and a timer setting method according to the present application will be described below in detail with reference to the drawings. Note that the distributed DB system and the timer setting method according to the present application are not limited by this embodiment.

[First embodiment]
In the following embodiments, the configuration of the distributed DB system according to the first embodiment, the configuration of the capture server, the processing flow of the capture server will be described in order, and finally the effects of the first embodiment will be described. .

[Configuration of distributed database system]
First, the distributed DB system according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a configuration of a distributed DB system according to the first embodiment. The distributed DB system 100 according to the first embodiment includes a capture server 10, a plurality of DB servers 20a to 20c, a client server 30, and a plurality of network devices (described as NW devices in FIG. 1) 40a and 40b. The DB servers 20a to 20c have the same configuration, and are described as the DB server 20 when they are described without distinction. Each network device 40a, 40b has the same configuration, and will be referred to as a network device 40 when it is described without distinction. Moreover, the number of each apparatus shown in FIG. 1 is an example to the last, and is not restricted to this.

  The capture server 10 acquires data flowing between the DB servers 20 from the network device 40 that relays communication between the DB servers 20. And the capture server 10 measures the delay time of the communication performed between the DB servers 20 from the acquired data, and stores it in the capture log storage part 13a mentioned later as a capture log.

  In addition, the capture server 10 classifies the delay times stored in the capture log storage unit 13 a for each DB server 20, and calculates the average and variance of the delay times between the DB servers 20. And the capture server 10 determines the timer value respectively set with respect to the delay time of the communication performed between each DB server 20 using the average and dispersion | distribution of the delay time between each DB server 20 calculated. .

  Each DB server 20 transmits an access request to another DB server 20 that stores data that is the target of the access request, or receives and returns an access request from the other DB server 20. In each DB server 20, when communicating between each DB server 20, delay time differs according to the influence of a communication distance, the structure of the network apparatus 40, etc., respectively.

  Here, the delay time in the distributed DB system 100 according to the first embodiment will be described with reference to FIG. FIG. 2 is a diagram for explaining the delay time in the distributed DB system according to the first embodiment. As illustrated in FIG. 2, in the distributed DB system 100, each DB server 20 is installed at a position away from each other so that the entire system does not stop. For example, it is assumed that the DB server 20a is installed in Tokyo, the DB server 20b is installed in Osaka, and the DB server 20c is installed in New York. Each DB server 20 is connected via a network (not shown). In the example of FIG. 2, it is assumed that the DB server 20a accepts an access request from the client server 30.

  For example, when the DB server 20b accommodates the data for which the access request has been received from the client server 30, the DB server 20a transmits the access request to the DB server 20b, and the data for which the access request has been received is transmitted to the DB server 20c. If it is accommodated, an access request is transmitted to the DB server 20c.

  Here, as shown in FIG. 2, the DB server 20a transmits the access request to the DB server 20c and receives the response, rather than the time required to transmit the access request to the DB server 20b and receive the response. The time is longer. In other words, regarding the DB server 20a, it is assumed that the delay in communication with the DB server 20b is small and the delay in communication with the DB server 20c is large. In the following description, the DB server 20a will be described as appropriate using an example in which an access request is received from the client server 30.

  The client server 30 transmits an access request to the DB server 20a. Then, the client server 30 receives the requested data from the DB server 20a. The network device 40 is a device that relays communication between the DB servers 20, and is, for example, a switch or a router. For example, the network device 40 has a so-called port mirroring function, copies data passing through a predetermined port, and transmits the copied data to the capture server 10.

[Capture Server Configuration]
Next, the configuration of the capture server 10 shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the capture server 10 according to the first embodiment. As illustrated in FIG. 3, the capture server 10 includes a communication processing unit 11, a control unit 12, and a storage unit 13. The processing of each of these units will be described below.

  The communication processing unit 11 controls communication related to various types of information exchanged with the DB server 20, the network device 40, and the like. For example, the communication processing unit 11 receives packets transmitted and received between the network device 40 and the DB server 20. In addition, the communication processing unit 11 transmits a timer value to be set to the DB server 20.

  The storage unit 13 stores data and programs necessary for various processes performed by the control unit 12. The storage unit 13 includes a capture log storage unit 13 a particularly closely related to the present invention. For example, the storage unit 13 is a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk.

  The capture log storage unit 13 a stores a delay time of communication performed between the DB servers 20. Specifically, as illustrated in FIG. 4, the capture log storage unit 13 a indicates “From” indicating the identifier of the DB server 20 that is the communication transmission source and the identifier of the DB server 20 that is the communication transmission destination. “To” and “TAT (Turn Around Time)” indicating the delay time are stored in association with each other.

  Referring to the example of FIG. 4, for example, the capture log storage unit 13 a determines that From (transmission source) “DB1”, To (transmission destination) “DB2”, and TAT (delay time) “0.001”. Are stored in association with each other. This means that the delay time of the packet transmitted from DB1 to DB2 is “0.001” seconds. In the following description, the DB server 20a is described as “DB1”, the DB server 20b is described as “DB2”, and the DB server 20c is described as “DB3”.

  The control unit 12 has an internal memory for storing a program that defines various processing procedures and necessary data, and performs various processes using them, and particularly as closely related to the present invention, A measurement unit 12a, a calculation unit 12b, a determination unit 12c, and a notification unit 12d are included.

  The measurement unit 12a measures a delay time of communication performed between the DB servers 20, and stores the measured delay time in the capture log storage unit 13a. For example, the measurement unit 12 a periodically acquires data flowing between the DB servers 20 from the network device 40 that relays communication between the DB servers 20. Then, the measurement unit 12a measures the delay time of communication performed between the DB servers 20 from the acquired data, and stores it in the capture log storage unit 13a as a capture log.

  Here, the process of measuring the delay time will be described with reference to FIG. FIG. 5 is a diagram illustrating a process for measuring the delay time. 5 shows an example in which the capture server 10 acquires data from the network devices 40a and 40b for the sake of simplification. However, the present invention is not limited to this example. Data may be acquired.

  As illustrated in FIG. 5, the capture server 10 includes a network device 40a that relays communication between the DB server 20a and the DB server 20b, and a network device that relays communication between the DB server 20a and the DB server 20c. Data is acquired from 40b. Then, the measuring unit 12a measures the delay time of communication performed between the DB server 20a and the DB server 20b and the delay time of communication performed between the DB server 20a and the DB server 20c from the acquired data. And stored in the capture log storage unit 13a as a capture log.

  The calculation unit 12b classifies the delay times stored in the capture log storage unit 13a for each DB server 20, and calculates the average and variance of the delay times between the DB servers 20. For example, the calculation unit 12b classifies the delay times stored in a predetermined period (for example, 12 hours) for each DB server 20, and calculates the average and variance of the delay times between the DB servers 20. Note that the calculation timing may be every predetermined period or may be a predetermined timing designated by the user.

  Further, as a process of classifying the delay time for each DB server 20, the calculation unit 12b classifies records having the same combination of From and To into the same group among the records stored in the capture log storage unit 13a. When From and To are reversed, records that are the same are also classified into the same group. In other words, for example, a record with From “DB1” and To “DB2” and a record with From “DB2” and To “DB1” are classified into the same group.

  The determination unit 12c uses the average and variance of the delay times between the DB servers 20 calculated by the calculation unit 12b, and sets timer values respectively set for the delay times of communication performed between the DB servers 20. decide. For example, the determination unit 12c determines, as a timer value, a value obtained by adding three times the variance to the average value of the delay times between the DB servers 20.

  Here, the process of notifying each DB server 20 of the timer value will be described with reference to FIG. FIG. 6 is a diagram for explaining processing for notifying each DB server of a timer value. As illustrated in FIG. 6, the determination unit 12c uses, as the timer value between DB1 and DB2, the TAT average of communication performed between DB1 and DB2 and three times the distribution σ of communication performed between DB1 and DB2. A value obtained by adding “3σ” which is the value of is calculated. In addition, the determination unit 12c uses the “TAT average” of communication performed between DB1 and DB3 as a timer value between DB1 and DB3, and a value three times the distribution σ of communication performed between DB1 and DB3. A value obtained by adding a certain “3σ” is calculated.

  The notification unit 12d notifies each DB server 20 of the timer value determined by the determination unit 12c. For example, the notification unit 12d notifies the DB server 20a and the DB server 20b of the timer value between DB1 and DB2 determined by the determination unit 12c. Further, the notification unit 12d notifies the DB server 20a and the DB server 20c of the timer value between DB1 and DB3 determined by the determination unit 12c. When receiving the timer value, the DB server 20 sets the timer value in each IF (Interface) of the own device.

  As described above, the capture server 10 can automatically perform timer design in consideration of the communication path between the DB servers 20. In addition, the capture server 10 can automatically perform a timer design that takes into account the influence of a communication path change after the construction of the distributed DB system 100.

[Capture server processing flow]
Next, a processing flow of the capture server 10 according to the first embodiment will be described with reference to FIG. FIG. 7 is a flowchart for explaining processing by the capture server according to the first embodiment.

  As shown in FIG. 7, the capture server 10 determines whether or not a predetermined period (for example, 12 hours) has elapsed (step S101). Here, the elapse of the predetermined period means, for example, that 12 hours have elapsed since the last timer value was determined. Here, if the predetermined period has not elapsed (No at Step S101), the capture server 10 measures the delay time of communication performed between the DB servers 20 until the predetermined period elapses, and measures the measured delay. Assume that the process of storing the time in the capture log storage unit 13a is repeated.

  Further, when the predetermined period has elapsed (Yes at Step S101), the capture server 10 classifies the delay times stored in the capture log storage unit 13a for each DB server 20, and delays between the DB servers 20. The average and variance are calculated (step S102).

  Subsequently, the capture server 10 determines a timer value set for each delay time of communication performed between the DB servers 20 using the calculated average and variance of the delay times between the DB servers 20. (Step S103). Then, the capture server 10 notifies each DB server 20 of the determined timer value (step S104).

[Effect of the first embodiment]
As described above, the capture server 10 of the distributed DB system 100 according to the first embodiment measures the delay time of communication performed between the DB servers 20, and stores the measured delay time in the capture log storage unit 13a. To do. The capture server 10 classifies the delay times stored in the capture log storage unit 13a for each DB server 20, and calculates the average and variance of the delay times between the DB servers 20. Subsequently, the capture server 10 determines a timer value to be set for each delay time of communication performed between the DB servers 20 using the calculated average and variance of the delay times between the DB servers 20. To do. Therefore, it is possible to appropriately set the timeout timer value.

  That is, the capture server 10 can automatically perform timer design considering the communication path between the DB servers 20. In addition, the capture server 10 can automatically perform a timer design that takes into account the influence of a communication path change after the construction of the distributed DB system 100.

  Further, the capture server 10 of the distributed DB system 100 according to the first embodiment notifies each DB server 20 of the determined timer value. For this reason, the capture server 10 can directly set a timer value for each DB server 20.

  Further, the capture server 10 of the distributed DB system 100 according to the first embodiment classifies the delay times stored in a predetermined period for each DB server 20, and averages and distributes the delay times between the DB servers 20. Is calculated. For this reason, the capture server 10 can calculate an appropriate average and variance of the delay time using the capture log accumulated in a predetermined period.

[Second Embodiment]
In the second embodiment described above, the case where the delay times stored in the predetermined period are classified for each DB server and the average and variance of the delay times between the DB servers is calculated has been described. The form is not limited to this. For example, when the number of delay time samples stored in a predetermined period is small, the average and variance of the delay times between the DB servers may be calculated using the delay times measured in the past.

  Therefore, in the following, when the number of samples of delay time stored in the storage unit 13 in the predetermined period is less than the predetermined threshold, the capture server 10A according to the second embodiment sets the past delay time to the past. A case will be described in which the average and variance of the delay times between the DB servers 20 are calculated by reading from the capture log storage unit 13b. In addition, description is abbreviate | omitted about the structure and process similar to the capture server 10 which concerns on 1st embodiment.

  First, the capture server 10A according to the second embodiment will be described with reference to FIG. FIG. 8 is a block diagram showing a configuration of a capture server according to the second embodiment. As shown in FIG. 8, the capture server 10A according to the second embodiment has a reading unit 12e, a past capture log storage unit, as compared with the capture server 10 according to the first embodiment shown in FIG. The difference is that it has 13b.

  The capture log storage unit 13a stores a capture log for determining a current timer value including a delay time measured within a predetermined period. On the other hand, the past capture log storage unit 13b stores a past capture log that was previously used to determine a timer value. For example, it is assumed that the capture log stored in the capture log storage unit 13a is stored as the past capture log every time the timer value is determined by the determination unit 12c in the past capture log storage unit 13b.

  When the number of samples of the delay time stored in the capture log storage unit 13a in the predetermined period is less than the predetermined threshold, the reading unit 12e stores the past data stored in the capture log storage unit 13a before the predetermined period. The delay time is read from the past capture log storage unit 13b. For example, the reading unit 12e determines whether or not the number of samples of the delay time stored in the capture log storage unit 13a within 12 hours after determining the previous timer value for each DB server 20 is less than a predetermined threshold value. Determine. As a result, when the number of samples of the delay time is less than the predetermined threshold, the reading unit 12e sets the past delay time for the delay information between the corresponding DB servers 20 to the number of samples equal to or greater than the predetermined threshold. It reads from the past capture log memory | storage part 13b by the part.

  The calculation unit 12b classifies the delay times stored in the capture log storage unit 13a during the predetermined period and the past delay times for each DB server 20, and calculates the average and variance of the delay times between the DB servers 20. To do.

  Here, a series of timer setting processes by the capture server 10A according to the second embodiment will be described with reference to FIG. FIG. 9 is a diagram for explaining a series of timer setting processes by the capture server 10A according to the second embodiment. The capture server 10A includes a network device 40a (not shown in FIG. 9) that relays communication between the DB server 20a and the DB server 20b, and a network device that relays communication between the DB server 20a and the DB server 20c. Data is acquired from 40b (not shown in FIG. 9). Here, in the example of FIG. 9, it is assumed that the communication traffic between the DB server 20a and the DB server 20b is small.

  Then, the capture server 10A measures the delay time of communication performed between the DB server 20a and the DB server 20b and the delay time of communication performed between the DB server 20a and the DB server 20c from the acquired data. And stored in the capture log storage unit 13a as a capture log.

  Then, the capture server 10A determines whether or not the number of samples of the delay time stored in the capture log storage unit 13a within 12 hours after determining the previous timer value is less than a predetermined threshold, for example, DB When the number of samples of the delay time of the communication performed between the server 20a and the DB server 20c is small, the past delay time for the delay information of the communication performed between the DB server 20a and the DB server 20c. Are read from the past capture log storage unit 13b by an amount corresponding to the number of samples exceeding a predetermined threshold.

  Thereafter, the capture server 10A classifies the delay times stored in the capture log storage unit 13a during the predetermined period and the past delay times for each DB server 20, and averages and distributes the delay times between the DB servers 20. Is calculated.

  Then, the capture server 10A adds “TAT average” of communication performed between DB1 and DB2 and “3σ” which is a value three times the variance σ of communication performed between DB1 and DB2. Is calculated. Further, the capture server 10A uses a value that is three times the “TAT average” of the communication performed between DB1 and DB3 and the variance σ of the communication performed between DB1 and DB3 as the timer value between DB1 and DB3. A value obtained by adding a certain “3σ” is calculated. Then, the capture server 10A notifies each DB server 20 of the calculated timer value.

  Next, an example of a processing procedure performed by the capture server according to the second embodiment will be described with reference to FIG. FIG. 10 is a flowchart for explaining processing by the capture server according to the second embodiment.

  As illustrated in FIG. 10, the capture server 10A determines whether or not a predetermined period (for example, 12 hours) has elapsed (step S201). Here, the elapse of the predetermined period means, for example, that 12 hours have elapsed since the last timer value was determined. Here, if the predetermined period has not elapsed (No at Step S201), the capture server 10A measures the delay time of communication performed between the DB servers 20 until the predetermined period elapses, and measures the measured delay. Assume that the process of storing the time in the capture log storage unit 13a is repeated.

  In addition, when the predetermined period has elapsed (Yes in step S201), the capture server 10A determines that the number of samples of the delay time stored in the capture log storage unit 13a within a predetermined 12 hours after determining the previous timer value is predetermined. It is determined whether it is less than the threshold value (step S202).

  As a result, when the number of samples is equal to or greater than the predetermined threshold (No at Step S202), the capture server 10A calculates the average and variance of the delay times between the DB servers 20 as in the first embodiment. (Step S204), and using the average and variance of the delay times between the DB servers 20, the timer values set for the delay times of the communications performed between the DB servers 20 are determined (Step S205). The determined timer value is notified to each DB server 20 (step S206).

  Further, when the number of samples is less than the predetermined threshold value (Yes at Step S202), the capture server 10A determines the past delay time stored in the capture log storage unit 13a before the predetermined period as the past capture log storage unit. Read from 13b (step S203). Specifically, when the number of samples of the delay time is less than a predetermined threshold, the capture server 10A sets the past delay time for the delay information between the corresponding DB servers 20, and the number of samples is equal to or greater than the predetermined threshold. Are read from the past capture log storage unit 13b.

  Then, the capture server 10A classifies the delay times stored in the capture log storage unit 13a during the predetermined period and the past delay times for each DB server 20, and averages and distributes the delay times between the DB servers 20. Is calculated (step S204). Subsequently, the capture server 10 </ b> A determines a timer value set for each delay time of communication performed between the DB servers 20 using the calculated average and variance of the delay times between the DB servers 20. (Step S205). Then, the capture server 10A notifies each DB server 20 of the determined timer value (step S206).

[Effect of the second embodiment]
As described above, the capture server 10A according to the second embodiment, when the number of samples of the delay time stored in the capture log storage unit 13a in the predetermined period is less than the predetermined threshold, is earlier than the predetermined period. The past delay time stored in the capture log storage unit 13a is read from the past capture log storage unit 13b. Then, the capture server 10A classifies the delay times stored in the capture log storage unit 13a during the predetermined period and the past delay times for each DB server 20, and averages and distributes the delay times between the DB servers 20. Is calculated. For this reason, the capture server 10A can set an appropriate timer value in each DB server 20 by using the past capture log even when the communication amount between the DB servers 20 is small. .

[System configuration, etc.]
Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  In addition, among the processes described in this embodiment, all or part of the processes described as being automatically performed can be manually performed, or the processes described as being manually performed All or a part of the above can be automatically performed by a known method. In addition, the processing procedure, control procedure, specific name, and information including various data and parameters shown in the above-described document and drawings can be arbitrarily changed unless otherwise specified.

[program]
FIG. 11 is a diagram illustrating a computer that executes a timer setting program. The computer 1000 includes, for example, a memory 1010 and a CPU (Central Processing Unit) 1020. The computer 1000 also includes a hard disk drive interface 1030, a disk drive interface 1040, a serial port interface 1050, a video adapter 1060, and a network interface 1070. These units are connected by a bus 1080.

  The memory 1010 includes a ROM (Read Only Memory) 1011 and a RAM 1012. The ROM 1011 stores a boot program such as BIOS (Basic Input Output System). The hard disk drive interface 1030 is connected to the hard disk drive 1090. The disk drive interface 1040 is connected to the disk drive 1100. For example, a removable storage medium such as a magnetic disk or an optical disk is inserted into the disk drive 1100. The serial port interface 1050 is connected to a mouse 1051 and a keyboard 1052, for example. The video adapter 1060 is connected to the display 1061, for example.

  The hard disk drive 1090 stores, for example, an OS 1091, an application program 1092, a program module 1093, and program data 1094. That is, the program that defines each process of the capture servers 10 and 10A is implemented as a program module 1093 in which code executable by a computer is described. The program module 1093 is stored in the hard disk drive 1090, for example. For example, a program module 1093 for executing processing similar to the functional configuration in the apparatus is stored in the hard disk drive 1090. The hard disk drive 1090 may be replaced by an SSD (Solid State Drive).

  The setting data used in the processing of the above-described embodiment is stored as program data 1094 in, for example, the memory 1010 or the hard disk drive 1090. Then, the CPU 1020 reads the program module 1093 and the program data 1094 stored in the memory 1010 and the hard disk drive 1090 to the RAM 1012 and executes them as necessary.

  The program module 1093 and the program data 1094 are not limited to being stored in the hard disk drive 1090, but may be stored in, for example, a removable storage medium and read out by the CPU 1020 via the disk drive 1100 or the like. Alternatively, the program module 1093 and the program data 1094 may be stored in another computer connected via a network (LAN (Local Area Network), WAN (Wide Area Network), etc.). Then, the program module 1093 and the program data 1094 may be read by the CPU 1020 from another computer via the network interface 1070.

10, 10A Capture server 11 Communication processing unit 12 Control unit 12a Measurement unit 12b Calculation unit 12c Determination unit 12d Notification unit 12e Reading unit 13 Storage unit 13a Capture log storage unit 13b Past capture log storage unit 20a, 20b, 20c DB server 30 Client Server 100 Distributed DB system

Claims (5)

A distributed DB system that communicates between DB servers installed in different locations,
Measuring a delay time of communication performed between each DB server, and storing the measured delay time in a storage unit;
Classifying the delay times stored in the storage unit for each DB server, and calculating a mean and variance of the delay times between the DB servers;
A determination unit that determines a timer value set for each delay time of communication performed between the DB servers, using an average and variance of the delay times between the DB servers calculated by the calculation unit;
A distributed DB system comprising:   The distributed DB system according to claim 1, further comprising a notification unit that notifies each DB server of the timer value determined by the determination unit.   2. The distributed DB system according to claim 1, wherein the calculation unit classifies delay times stored in a predetermined period for each DB server, and calculates an average and variance of the delay times between the DB servers. . When the number of samples of the delay time stored in the storage unit during the predetermined period is less than a predetermined threshold, a reading unit that reads a past delay time stored in the storage unit before the predetermined period In addition,
The calculation unit classifies the delay time stored in the storage unit during the predetermined period and the past delay time for each DB server, and calculates an average and variance of the delay times between the DB servers. The distributed DB system according to claim 3. A timer setting method executed by a distributed DB system that communicates between DB servers installed in different places,
A measurement step of measuring a delay time of communication performed between each DB server, and storing the measured delay time in a storage unit;
A calculation step of classifying the delay times stored in the storage unit for each DB server, and calculating an average and variance of the delay times between the DB servers;
A determination step of determining a timer value set for each delay time of communication performed between the DB servers, using an average and variance of delay times between the DB servers calculated by the calculation step;
The timer setting method characterized by including.

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