JP2017021576A - Control information setting device, control information setting method, and control information setting program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control information setting device capable of processing a processing request in a short period of time.SOLUTION: A control information setting device 151 includes a reachable information setting part 152, and a log buffer 153. In the log buffer, storage areas which can store log information, and control information including reachable information representing whether or not log information following the log information in a prescribed sequence can be referred to and size information of the log information while the log information is associated with the control information are arranged in a prescribed sequence. The reachable information setting part reads reachable information from a first control information recorded in a storage area representing a boundary between a storage area with recording processing of the log information have been allocated and a storage area unallocated with the recording processing, sets an unreachable state in the reachable information, sets a size existing in the size information, and specifies second control information representing that the size information satisfies a prescribed condition according to a sequence in the log buffer to set a reachable state in the case that the read reachable information is reachable.SELECTED DRAWING: Figure 16

Description

  The present invention relates to, for example, a control information setting device that manages a log buffer shared by a plurality of devices.

  Among information systems that write information to a file, a database (hereinafter, sometimes referred to as “DB” in this application), etc., an information system that requires high reliability uses information related to a write operation as log information. A method of recording in a log buffer different from that of a file or database is often adopted. For example, an information system that requires high reliability is a system that is not allowed to lose written information. A database management system is an example of an information system that requires high reliability.

  For example, Patent Documents 1 to 3 disclose an example of a database management system that requires high reliability.

  The database management system disclosed in Patent Literature 1 includes a shared DB data management unit, a data processing unit, and a prefetching unit. In response to a request for the data processing unit to acquire data, the shared DB data management unit executes processing for acquiring the data after executing exclusive control relating to the data. The shared DB data management unit further reads data that is a prefetch target in response to a request that the prefetch unit prefetches the data.

  The database management system disclosed in Patent Literature 2 includes a shared DB data management unit, a data processing unit, and a prefetching unit. The shared DB data management unit specifies a process associated with the request and a lower limit value associated with the request in response to the request for the prefetching unit to refer to the data. When the period between the current time and the time when the latest input / output process is executed is shorter than the specified lower limit value, the shared DB data management unit until the period exceeds the specified lower limit value , Interrupt the specified process. The shared DB data management unit further executes exclusive control related to the data and the data acquisition process in response to a request for the data processing unit to acquire the data.

  The database management device disclosed in Patent Document 3 has a plurality of computers that manage a data set including a plurality of data. Among the plurality of computers, the first computer stores the first data in the memory in response to a request to store the first data, and further creates first duplicate data that is a duplicate of the first data. The first computer calculates the number of times the first duplicate data is transmitted to the second computer based on the success probability that the duplicate data can be stored in the second computer. The first computer transmits the first copy data to the second computer for the calculated number of times.

  Hereinafter, for convenience of explanation, in this specification, an operation for storing (saving) information in a file, a database, or the like is represented as “write”. An operation for storing (saving) log information related to a write operation in a log recording medium different from a database or the like is represented as “record”. In addition, “parallel” includes parallel and pseudo-parallel.

  In a database system, processing requests (transactions) for a plurality of databases are often executed in parallel. For example, in the database system, a plurality of processes that execute processes related to transactions operate in parallel. Even in the case where a plurality of processes operate in parallel, the database system needs to correctly execute processing related to transactions. Therefore, in the database system, it is necessary for a plurality of processes to execute a write operation to a file or a database and recording log information related to the write operation without contradicting each other.

  An example for realizing this processing will be described. The database system has a log buffer capable of recording log information and its control information in a shared memory accessible by all processes that may record log information. Each process executing processing in the database system records log information related to the write operation in the log buffer while maintaining the consistency of the mutual processes.

  Next, a memory device that implements the log buffer will be described.

Memory elements different from DRAMs are provided as memory elements constituting the computer system. Note that DRAM represents an abbreviation of Dynamic_Random_Access_Memory. The memory element has the following characteristics:
Even if power is not supplied to the computer system, the data that was retained during the period when power was supplied (non-volatile),
A characteristic (byte addressable) that data can be directly read from and written to the memory element by a machine language instruction to the central processing unit (CPU).

  The memory element can be realized by a mode using a memory element having non-volatile characteristics such as PRAM and MRAM. In addition, the memory element can be realized by, for example, a mode in which a volatile memory element and a block access type element such as a battery and an SSD that are non-volatile but not byte-addressable are combined. The computer system adopting the combination mode is a non-volatile block access type in which data recorded in a volatile memory element is stored using power supplied from a battery when power is not supplied. Store in the element. The computer system stores the data stored in the block access type element in the volatile memory element when the power is restored. According to this combination mode, even a volatile memory element can be handled like a non-volatile memory, so that non-volatility can be realized.

  In the above description, PRAM represents an abbreviation for Parameter_Random_Access_Memory. MRAM represents an abbreviation for Magnetoresistive_Random_Access_Memory. SSD represents an abbreviation for Solid_State_Drive.

  Hereinafter, for convenience of description, a memory element having non-volatility is referred to as “non-volatile memory (NVRAM)” regardless of the mode of realizing non-volatility.

  Next, an example in which the above-described nonvolatile memory is used as a log buffer in the database system will be described.

  Non-Patent Document 1 discloses a method using a non-volatile memory as a log buffer. According to Non-Patent Document 1, a plurality of processes acquire an exclusive control right related to the log buffer by exclusive control related to the log buffer, and the end of the log buffer within a period during which the acquired exclusive control right is held. Next, an operation for securing a storage area (log storage area) (hereinafter referred to as a “log area securing operation”) is executed. The storage area secured by the log area securing operation can store, for example, data indicating the size (length, size) of log information to be stored (hereinafter referred to as “length”). It includes a length area and a flag area capable of storing a flag representing a state in which a storage process related to the log information is being executed. Hereinafter, the flag is referred to as “copying flag”.

  The process that has acquired control regarding the log buffer records log information in the reserved storage area.

The log area securing operation can be realized by, for example, the following function 1 and function 2. That is,
Function 1: A function for updating control information related to the log buffer (for example, a pointer indicating the end of the log buffer),
Function 2: The size of the log information is recorded in the length area of the secured storage area, and a value indicating that the storage process is being performed is recorded in the flag area of the secured storage area.

  According to Non-Patent Document 1, when a failure occurs in the own system, the database management system records a file storing the contents at a certain temporary point (checkpoint) of the database and an operation history after the checkpoint. Refer to log information. The database management system recovers data up to the checkpoint based on the referenced file, and then executes a write operation on the referenced log information on the file, immediately before the occurrence of the failure. Restore the contents of the database.

  Non-Patent Document 2 discloses a method of reducing contention by using a plurality of log buffers.

Japanese Patent No. 5261809 Patent No. 5098120 Japanese Patent No. 55488829

Fang, Ru and Hsiao, Hui-I and_He, Bin and Mohan, C and Wang, Yun, “High_performance_database_de_13_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E_E Wang, Tianzheng and Johnson, Ryan, "Scalable logging through non-volatile memory", Very Large Data Bases (VLDB) 2014, p865-876. Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A: Instruction Set Reference, A-M, (http://www.tel.com/Fs.

  As described above, a database management system that manages a plurality of processing requests for a database performs exclusive control on a log buffer shared by a plurality of information processing apparatuses such as log information. This is because it is necessary for the database management system to correctly execute processing regarding log buffers shared by a plurality of information processing apparatuses.

  Even if the database management system has a plurality of arithmetic devices that execute processing according to the processing request, the database management system must execute the processing sequentially during the period during which exclusive control is being executed. Don't be. For example, the devices (systems and methods) disclosed in Patent Document 1 to Patent Document 3, Non-Patent Document 1, and Non-Patent Document 2 are shared within a period of having the exclusive control right. A lot of processing is sequentially performed on the log buffer.

  However, since the database management system must sequentially execute processing within a period during which it has exclusive control rights, for example, Patent Document 1 to Patent Document 3, Non-Patent Document 1, and Non-patent The apparatus disclosed in Document 2 has a reduced processing efficiency.

  Therefore, a main object of the present invention is to provide a control information setting device or the like that efficiently sets control information in a storage area so that a processing request for a log buffer can be processed in a short time.

In order to achieve the above object, in one aspect of the present invention, a control information setting device includes:
Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to A log buffer in which storage areas that can be stored in association with control information including size information indicating the size of the log information and the reachable information indicating the size of the log information are logically arranged in the order;
In the log buffer, the first control information recorded in a storage area that represents a boundary between a storage area to which the recording process for recording the log information has been assigned and a storage area to which the recording process is not assigned is enabled from the first control information. Read information, set the unreachable state in the reachable information included in the first control information, set the size in the size information included in the first control information, and read When the reachable information is in the reachable state, second control information indicating that the size information satisfies a predetermined condition is specified according to the order in the log buffer, and the specified second control information Reachability information setting means for setting the included reachability information to the reachable state.

As another aspect of the present invention, the control information setting method includes:
Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to And a log buffer in which storage areas that can be stored in association with control information including size information indicating the size of the log information are logically arranged in the order.
In the log buffer, the first control information recorded in a storage area that represents a boundary between a storage area to which the recording process for recording the log information has been assigned and a storage area to which the recording process is not assigned is enabled from the first control information. Read information, set the unreachable state in the reachable information included in the first control information, set the size in the size information included in the first control information, and read When the reachable information is in the reachable state, second control information indicating that the size information satisfies a predetermined condition is specified according to the order in the log buffer, and the specified second control information The reachability information included is set to the reachable state.

  Furthermore, this object is also realized by such a control information setting program and a computer-readable recording medium for recording the program.

  According to the control information setting device and the like according to the present invention, it is possible to efficiently set control information that enables processing requests to the log buffer to be processed in a short time in the storage area.

It is a block diagram which shows the structure which the database management apparatus which concerns on the 1st Embodiment of this invention has. It is a figure which shows notionally the structure which the log buffer which concerns on 1st Embodiment has. It is a block diagram which shows the structure which the log information which concerns on 1st Embodiment has. It is a block diagram which shows the structure which a log buffer information storage part has. It is a flowchart (1/2) which shows the flow of a process in the database management apparatus which concerns on 1st Embodiment. It is a flowchart (2/2) which shows the flow of a process in the database management apparatus concerning 1st Embodiment. It is a figure showing an example of control information notionally. 3 is a flowchart illustrating a processing flow in the database management apparatus. It is a flowchart showing the flow of the process in the head position calculation part which concerns on 1st Embodiment. It is a flowchart showing the flow of a process in the log process part (1/3) which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process in the log process part (2/3) which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process in the log process part (3/3) which concerns on 1st Embodiment. It is a flowchart showing the flow of the process in the reachable position information update part which concerns on 1st Embodiment. It is a flowchart which shows the flow of the process in the reachable position information update part which concerns on 1st Embodiment. It is a flowchart showing the flow of the process in the completion position information update part which concerns on 1st Embodiment. It is a block diagram which shows the structure which the database management apparatus concerning the 2nd Embodiment of this invention has. It is a flowchart which shows the flow of a process in the control information setting apparatus 151 which concerns on 2nd Embodiment. It is a block diagram which shows roughly the example of hardware constitutions of the calculation processing apparatus which can implement | achieve the database management apparatus concerning each embodiment of this invention.

  First, multiprocessor instructions capable of realizing a part of functions in the database management apparatus according to each embodiment of the present invention will be described. As for the multiprocessor instruction, for example, Non-Patent Document 3 discloses a “cmpxchg” instruction which is an instruction related to an Intel x86 processor. The “cmpxchg” instruction represents a Compare_and_Exchange instruction. The “cmpxchg” instruction may be referred to as a Compare_and_Swap (Cas) instruction. Note that multiprocessor instructions capable of realizing a part of the functions are not limited to the above-described example.

  The “cmpxchg” instruction includes, for example, position information indicating the position of a certain storage area, a first value, and three operands of a second value. The position information is, for example, a name representing a register in the database system (eax register, rax register in the case of 64 bit_mode, and so on). For convenience of explanation, it is assumed that the position information is an eax register. The “cmpxchg” instruction is an instruction for executing a series of operations shown in the process 1 and the process 3 atomically (described later).

Process 1: Read the first value
Process 2: When the read first value matches the value stored in the eax register, the second value is stored in the memory area in which the first value was stored.
Process 3: When the read first value does not match the value stored in the eax register, the read first value is stored in the eax register.

  Next, atomic will be described. In atomic processing, hardware guarantees that a processor different from a certain processor cannot execute processing on the storage area while the processor executes a series of processes on the storage area. Indicates processing. For example, the “cmpxchg” instruction guarantees by hardware that another processor does not access the storage area while a certain processor is executing the process 1 to process 3 on the storage area. Indicates that the process is in progress.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

<First Embodiment>
The configuration of the database management apparatus 101 according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a block diagram showing the configuration of the database management apparatus 101 according to the first embodiment of the present invention.

  The database management apparatus 101 according to the first embodiment of the present invention roughly includes a plurality of transaction execution units, a log buffer 112, and a log buffer information storage unit 111. The plurality of transaction execution units are, for example, a transaction execution unit 107, a transaction execution unit 109, and a transaction execution unit 110. The transaction execution unit 107 includes a log processing unit 102 and a memory 108. The log processing unit 102 includes a head position calculation unit 103 and a log information storage unit 104. The log information storage unit 104 includes a reachable position information update unit 105 and a completed position information update unit 106. The transaction execution unit 109 and the transaction execution unit 110 have the same configuration as the transaction execution unit 107.

  The database management apparatus 101 illustrated in FIG. 1 has three transaction execution units, but the number is not necessarily limited to three.

  The log buffer 112 is realized using, for example, NVRAM representing a non-volatile memory element. The configuration of the log buffer 112 will be described in detail with reference to FIG. FIG. 2 is a diagram conceptually illustrating the configuration of the log buffer 112 according to the first embodiment.

  The log buffer 112 can store at least one log information set in which, for example, log information output in a write operation related to log information and control information related to the log information are associated with each other. In the example illustrated in FIG. 2, the log buffer 112 includes a first log information set representing information associated with log information 1 and control information 1, and second log information representing information associated with log information 2 and control information 2. Includes sets, etc.

  The log information set may be recorded in the log buffer 112 in the order of control information and log information associated with the control information. In the present embodiment, it is assumed that the log buffer 112 stores control information and log information associated with the control information at least logically in the order recorded. For example, the control information is a size to which the above-described “cas” instruction can be applied, for example, information having a size of one word.

  The control information regarding log information will be described in detail with reference to FIG. FIG. 3 is a block diagram illustrating a configuration of log information according to the first embodiment.

  The control information includes reachability information, recording operation completion information, recording operation state information, and size (length, length, size) information. That is, the control information has a data structure including reachable information.

  The reachable information is information indicating whether or not it is possible to refer to the log information sets positioned in the subsequent order with respect to each log information set in the log buffer 112. That is, the reachable information is in a reachable state representing a state in which it is possible to refer to a log information set subsequent to a certain log information set in a predetermined order in the log buffer 112 or can be referred to. This is information indicating whether it is an unreachable state representing an impossible state. For example, the state in which the log information set positioned in the rear order can be referred to is 1 (valid), and the value incapable of referring to the log information set positioned in the back order is 0 (invalid). . The reachable information is information (for example, a flag) that is referred to when determining whether or not to update reachable position information (described later). In the following description, for convenience of explanation, it is assumed that a storage area capable of storing reachable information is represented as a variable “rflag”. Let us say that a state in which log information sets positioned in the subsequent order can be referred to as a “reachable state”. In addition, a state in which it is impossible to refer to log information sets positioned in the subsequent order is referred to as an “unreachable state”. The variable “rflag” represents a specific storage area in the log buffer 112 or the memory 108. Note that the reachable information may be expressed as, for example, a reachable state control flag. For example, the reachable information is in a reachable state before the process related to the log information associated with the control information including the reachable information is assigned, and is in an unreachable state after the process is assigned.

  The recording operation completion information is information indicating whether or not the processing for recording the log information in the log buffer 112 is completed. For example, the state before the process of recording the log information in the log buffer 112 is 1 (valid), and the value is 0 (invalid) when the process is after the process is completed. The recording operation completion information is information (for example, a flag) referred to when determining whether or not to update completion position information (described later). In the following description, it is assumed that a storage area in which recording operation completion information can be stored is represented as a variable “cflag”. A state before the process is completed is represented as an “incomplete state”. Further, the state after the completion of the processing is represented as “completion state”. For example, the variable “cflag” represents a specific storage area in the log buffer 112 or the memory 108. Note that the recording operation completion information may be represented as a completion control flag, for example. For example, the recording operation completion information represents an incomplete state when the processing related to the log information associated with the control information including the recording operation completion information is before completion, and represents a completion state after completion.

  The recording operation state information is information indicating whether or not a process of recording log information in the log buffer 112 is being executed. For example, the state that is being processed is 1, and the state that is not being processed is 0. In the following description, it is assumed that a storage area in which recording operation state information can be stored is represented as a variable “inCopy”. For example, the variable “inCopy” represents a specific storage area in the log buffer 112 or the memory 108. Note that the recording operation state information may be represented as a processing flag. Further, in the following description, it is assumed that the state in which the process is being executed is represented as a “processing state”. Assume that a state in which processing is not executed is represented as a “non-processing state”.

  The size information represents a size (size, length, length) related to log information. In the following description, a storage area that can store size information is also referred to as a variable “length”. For example, the variable “length” represents a specific storage area in the log buffer 112 or the memory 108.

  Next, the configuration of the log buffer information storage unit 111 will be described with reference to FIG. FIG. 4 is a block diagram illustrating a configuration of the log buffer information storage unit 111.

  The log buffer information storage unit 111 includes reachable position information, completion position information, and head position information.

  The reachable position information stores, in the log buffer 112, a log information set whose position is located in the last order among log information sets including a reachable state indicating a state in which the process of recording the log information is started. Represents the position. In the following, for convenience of explanation, it is assumed that a storage area capable of storing reachable position information in the log buffer information storage unit 111 is represented as a variable “ReachableUpTo”.

  The completion position information represents a position in the log buffer 112 that stores a log information set whose position is located in the rearmost order among log information sets in a completion state representing a state in which the process of recording the log information is completed. . Hereinafter, for convenience of explanation, a storage area in the log buffer information storage unit 111 that can store completion position information is represented as a variable “FinishedUpTo”.

  The head position information represents a position in the log buffer 112 where a log information set to which a process for recording log information has not yet been assigned can be stored. Hereinafter, for convenience of explanation, it is assumed that a storage area in the log buffer information storage unit 111 that can store head position information is represented as a variable “TAIL”.

  For convenience of explanation, in this embodiment, it is assumed that the log buffer 112 stores N log information sets. The log identifier that can uniquely identify the log information is assumed to be the order of the log information set in the log buffer 112. For example, in the example shown in FIG. 2, the log information I (where I represents a natural number) and the I-th log information set representing information associated with the control information I are represented. In addition, the head position information is the position closest to the storage area in which N log information sets are stored among the areas in which a new log information set can be stored (in this example, the (N + 1) th log Information set).

  In the following description, regarding the control information included in the (N + 1) th log information set, the variable “rflag” stores 1 (that is, the reachable state), and the variable “cflag” is 1 ( That is, it is assumed that the incomplete state is stored. Furthermore, regarding the control information, it is assumed that the variable “inCopy” stores 0 (that is, the non-processing state), and the variable “length” stores 0.

  Next, processing in the database management apparatus 101 according to the present embodiment will be described with reference to FIGS. 5 and 6. 5 and 6 are flowcharts showing the flow of processing in the database management apparatus 101 according to the first embodiment.

  The transaction execution unit 107 executes a process related to the transaction in response to a request for instructing a transaction related to a search process executed on the database (step S101).

  In the processing shown in step S101, for example, the transaction execution unit 107 uses the position information indicating the storage area where the log information related to a certain write operation is stored and the size information indicating the size of the log information as the head position calculation unit 103. (Step S102).

  The head position calculation unit 103 receives the size information output from the transaction execution unit 107. The head position calculation unit 103 preferentially performs processing related to a storage area (for example, the variable “TAIL”) that stores head position information among the log buffer information storage units 111 shared by a plurality of transaction execution units. An exclusive control right that can be executed is acquired (step S103). The head position calculation unit 103 reads the head position information stored in the variable “TAIL” within the period during which the exclusive control right is acquired (step S104).

  The start position calculation unit 103 adds the size represented by the input size information and the read start position information (step S105), and has the exclusive control right to acquire the value calculated as a result of the addition. Within the period, it is stored in the variable “TAIL” in the log buffer information storage unit 111 (step S106). The head position calculation unit 103 releases the acquired exclusive control right (step S107). The head position calculation unit 103 outputs the head position information read in step S104 to the log information storage unit 104 as first head information (step S108).

  Note that the information acquired by the head position calculation unit 103 differs among a plurality of transaction execution units due to control using the exclusive control right. Further, when the head position calculation unit 103 releases the exclusive control right, the head position calculation unit in another transaction execution unit (for example, the transaction execution unit 109 or the transaction execution unit 110) acquires the head position information. be able to.

  The log information storage unit 104 receives the first head information output from the head position calculation unit 103, the size of log information output from the transaction execution unit 107, and the position information output from the transaction execution unit 107. The log information storage unit 104 stores control information stored in a storage area starting from the read head position information (that is, the position storing the (N + 1) th log information set) in the log buffer 112. The reachable information included in the read control information is stored in the memory 108.

  The log information storage unit 104 controls the control information (hereinafter, “second control information”) including the unachievable state, the recording operation completion information included in the input control information, the in-process state, and the size of the input log information. (Step S111). The log information storage unit 104 records the created second control information in a storage area starting from the input first head information (step S112).

  When the reachable information stored in the memory 108 is in a reachable state (YES in step S113), the log information storage unit 104 performs an operation (described later) for updating the reachable position information (described later). (Step S114). The log information storage unit 104 does not instruct the reachable position information update unit 105 to update the reachable position information when the reachable information stored in the memory 108 is not reachable (NO in step S113).

  The log information storage unit 104 is stored in the storage area starting from the first head information input prior to step S111 in the log buffer 112 and the storage area starting from the position information input prior to step S111. Log information is recorded (step S115). The log information storage unit 104 reads the control information stored in the storage area starting from the read first head information, and stores the recording operation completion information included in the read control information in the memory 108 ( Step S116). The log information storage unit 104 includes control information (hereinafter referred to as “third control information” including the reachable information in the control information read in step S116, the completion status, the non-processing status, and the size of the log information in the control information. Is expressed) (step S117).

  When the recording operation completion information stored in the memory 108 in step S116 is in an incomplete state (YES in step S118), the log information storage unit 104 performs a process (described later) for updating the completion position information (described later). The updating unit 106 is instructed (step S119). When the recording operation completion information stored in the memory 108 in step S116 is not in an incomplete state (NO in step S118), the log information storage unit 104 performs processing for updating the completion position information to the completion position information update unit 106. Do not instruct.

  The log information storage unit 104 compares the input first head information and a value obtained by adding the input size (that is, second head information) with the reachable position information stored in the log buffer information storage unit 111. . When the reachable position information is equal to or greater than the second head information (YES in step S120), the log information storage unit 104 ends the operation for recording the log information. In contrast, when the reachable position information is less than the second head information (NO in step S120), the log information storage unit 104 waits until the reachable position information becomes equal to or more than the second head information. Processing is executed (step S121).

  Next, processing according to the present embodiment will be described with reference to an example of an information processing apparatus having a plurality of processors.

  For convenience of explanation, it is assumed that the control information represents data that can be handled by an atomic operation by a multiprocessor instruction. Further, an atomic operation by a multiprocessor instruction can be realized by using, for example, the above-described “cmpxchg” instruction. In this example, it is assumed that the process for acquiring the exclusive control right is represented as “LockAcquire”, and the process for releasing the acquired exclusive control right is represented as “LockRelease”.

  The process for acquiring the exclusive control right and the process for releasing the exclusive control right are often implemented using atomic operations via multiprocessor instructions. There are various methods for realizing the process of acquiring the exclusive control right and the process of releasing the acquired exclusive control right. Here, a detailed description of the method for realizing the exclusive control right is omitted.

  Furthermore, the database management apparatus 101 completes the process of recording up to the Nth log information set in the log buffer 112, and then refers to the database according to the present embodiment with reference to an example in which no new transaction is processed. Processing in the management apparatus 101 will be described. In this example, it is assumed that the variable “ReachableUpTo”, the variable “FinishedUpTo”, and the variable “TAIL” first store a position representing a storage area in which the (N + 1) th log information set is recorded. .

  In the example, as shown in FIG. 7, regarding the control information included in the (N + 1) th log information set, the variable “rflag” that can record the reachable information is set to the reachable state (ie, Suppose that 1) is recorded. FIG. 7 is a diagram conceptually illustrating an example of the control information. It is assumed that the variable “cflag” that can record the recording operation completion information records an incomplete state (that is, 1). Regarding the control information, it is assumed that the variable “inCopy” that can record the recording operation state information records a non-processing state (that is, 0). It is assumed that 0 is recorded in the variable “length” in which the size information can be recorded. That is, in the control information included in the (N + 1) th log information set, the reachable information is in a reachable state, and the recording operation completion information is in an uncompleted state. In the control information included in the (N + 1) th log information set, the recording operation state information is in a non-processing state, and the size information is 0.

  Assume that each process is assigned to an area in a shared memory (not shown in FIG. 1). That is, the shared memory includes a storage area for the I-th (where 1 ≦ I ≦ n) process. The I process stores the log information generated when the transaction execution unit 107 executes the transaction process in the log information area in the storage area allocated to the I process.

  Processing in the database management apparatus 101 will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of processing in the database management apparatus 101.

  The processing in the database management apparatus 101 is roughly divided into processing for calculating first head information indicating a storage area for recording a log information set (step S125), and recording the log information set in an area indicated by the calculated first head information. Processing (step S126).

  An overview of the processing in steps S125 and S126 will be described.

Step S125:
The head position calculation unit 103 receives the size information output from the transaction execution unit 107, for example. The head position calculation unit 103 reads the head position information in the log buffer information storage unit 111 and outputs the read head position information (that is, the first head information) to the log information storage unit 104. The process executed by the head position calculation unit 103 can be realized by using, for example, a “reserve” function that can secure a storage area. The “reserve” function represents, for example, a function that receives information indicating the size of log information as input and secures a storage area for the input size.

Step S126:
The log information storage unit 104 receives the first head information output from the head position calculation unit 103, the size of log information output from the transaction execution unit 107, and the position information output from the transaction execution unit 107. The log information storage unit 104 records a log information set related to the log information stored in the position information in a storage area represented by the first head information input in the log buffer 112.

  The process executed by the log information storage unit 104 can be realized by using a copy function capable of storing data in a storage area, for example. The log information storage unit 104 inputs three pieces of information shown in the following inputs 1 to 3 by performing processing according to a copy function, for example.

Input 1: Information indicating a position (first position) in the process specific memory in which log information to be recorded in the storage area is stored,
Input 2: Size information indicating the size of the log information,
Input 3: Information indicating the position (second position) of the storage area secured by the log area securing operation or the like.

  For example, the log information storage unit 104 processes the log information stored in the storage area starting from the first position into the storage area starting from the second position for the received size by processing according to the copy function. Record.

  Next, before describing the processing in step S125 and step S126 in detail, variables representing storage areas in the memory 108 and the like will be described.

  For convenience of explanation, in each transaction execution unit, the variable “myLSN”, the variable “myLog”, the variable “myLength”, the variable “nextLSN”, the variable “myTurn”, the variable “oldv”, and the variable “newv” Assume that a specific storage area in the memory within the transaction execution unit is represented. Further, buffer represents the log buffer 112. Further, buffer [myLSN] represents a storage area indicated by a value stored in the variable “myLSN” in the log buffer 112.

  Regarding the control information, it is assumed that the reachable information is stored in a variable “rflag” representing a storage area in the log buffer 112, for example. For example, it is assumed that the recording operation completion information is stored in a variable “cflag” representing a storage area in the log buffer 112. For example, it is assumed that the recording operation state information is stored in a variable “inCopy” representing a storage area in the log buffer 112. For example, it is assumed that the size information is stored in a variable “length” representing a storage area in the log buffer 112.

  It is assumed that the reachable position information is stored in a variable “ReachableUpTo” representing a storage area in the log buffer information storage unit 111. The completion position information is assumed to be stored in a variable “FinishedUpTo” representing a storage area in the log buffer information storage unit 111. The head position information is assumed to be stored in a variable “TAIL” representing a storage area in the log buffer information storage unit 111.

  The process shown in step S125 (FIG. 8) executed by the head position calculation unit 103 will be described in more detail with reference to FIG. FIG. 9 is a flowchart showing processing in the head position calculation unit 103 according to the first embodiment.

  The head position calculation unit 103 acquires the exclusive control right for the variable “TAIL” in which the head position information is stored in the log buffer information storage unit 111 (step S131). The head position calculation unit 103 reads the head position information stored in the variable “TAIL” within the period during which the exclusive control right is acquired (step S132). The start position calculation unit 103 stores the read start position information in the variable “myLSN” (step S133). The start position calculation unit 103 adds the size included in the input size information to the read start position information (step S134), and calculates the calculated value within a period during which the exclusive control right is acquired. The data is stored in the variable “TAIL” in the buffer information storage unit 111 (step S135). The head position calculation unit 103 releases the acquired exclusive control right (step S136), and outputs the value stored in the variable “myLSN” (that is, the first head information) to the log information storage unit 104 (step S136). S137).

  That is, by the processing shown in steps S131 to S137, the head position calculation unit 103 outputs, in the log buffer 112, first head information indicating a storage area to which no log information is allocated, and further relates to the head position information. Update the storage area. In the processes shown in steps S131 to S137, the head position calculation unit 103 reads the head position information by executing a process similar to the process instructed by the “reserve” function, for example. The head position calculation unit 103 acquires the exclusive control right by executing a process similar to the process instructed by the function “Lock_Acquire”, for example.

  The process executed by the log information storage unit 104 in step S126 (FIG. 8) will be described in more detail with reference to FIG. FIG. 10 is a flowchart (1/3) showing processing in the log processing unit 102 according to the first embodiment.

  The log information storage unit 104 receives the position information output from the transaction execution unit 107, the size information output from the transaction execution unit 107, and the first head information output from the head position calculation unit 103. More specifically, the log information storage unit 104 stores the input position information in the variable “myLog”, stores the input size information in the variable “myLength”, and stores the input first head information in the variable “myLSN”. To store.

  The log information storage unit 104 adds the input first head information and the input size information to thereby add the head position information (that is, “second head information”) where the log information set can be recorded next. calculate. More specifically, the log information storage unit 104 stores the value stored in the variable “myLength” storing the size information and the variable “myLSN” storing the first head information. Are added (step S141), and the calculated result (ie, “second head information”) is stored in the variable “nextLSN” (step S142).

  Next, the log information storage unit 104, in the log buffer 112, the log information set recorded in the storage area represented by the input first head information, and the control information included in the log information set (hereinafter, (Referred to as “first control information”). More specifically, the log information storage unit 104 reads the log information set stored in the storage area buffer [myLSN] (step S143), and sets the first control information in the read log information set as a variable “oldv”. (Step S144).

  Next, the log information storage unit 104 reads the reachable information included in the read first control information, and stores the read reachable information in the memory 108. More specifically, the log information storage unit 104 reads the reachability information stored in the variable “rflag” out of the first control information stored in the variable “oldv”, and converts the read reachability information into the variable Stored in “myTurn” (step S145).

  Next, the log information storage unit 104 controls the control information including the unreachable state, the recording operation completion information included in the input control information, the processing state, and the size indicated by the size information of the input log information (hereinafter, , Expressed as “second control information”). More specifically, the log information storage unit 104 stores the first control information stored in the variable “oldv” in the variable “newv” (step S146). The log information storage unit 104 stores the size information in the variable “myLength” in the variable “length” included in the variable “newv” (step S147). Furthermore, the log information storage unit 104 stores a processing state (for example, 1) in a variable “inCopy” included in the variable “newv”. Further, the log information storage unit 104 stores an unreachable state (for example, 0) in the variable “rflag” included in the variable “newv” (step S148).

  Next, the log information storage unit 104 stores the second control information in the storage area represented by the input first head information by executing a process similar to the process executed by the “cas” instruction.

  The process for storing the second control information will be described in detail. The log information storage unit 104 reads the control information (hereinafter referred to as “third control information”) in the log information set recorded in the storage area represented by the input first head information, and the read third control information and Then, it is determined whether or not the first control information matches.

  When the first control information matches the third control information, the log information storage unit 104 stores the second control information in the storage area represented by the input first head information. That is, in this case, the log information storage unit 104 performs control including the unreachable state, the recording operation completion information included in the input control information, the processing state, and the size indicated by the size information of the input log information. Information is stored in a storage area in which the log information set is stored.

  When the third control information and the first control information do not match, the log information storage unit 104 sets the read third control information as the first control information. Thereafter, the log information storage unit 104 reads the reachable information included in the read first control information (corresponding to step S145), or the third control information and the first control information match. Is executed (corresponding to step S149 (described later)). That is, the log information storage unit 104 executes the processes shown in steps S145 to S150 (described later) until the created second control information is stored in the storage area represented by the input first head information.

  A process similar to the process executed by the “cas” instruction as described above is executed atomically. More specifically, a process for executing the same process as that executed by the “cas” instruction will be described.

  The log information storage unit 104 determines whether or not the first control information stored in the variable “oldv” matches the control information stored in the storage area buffer [myLSN] (step S149). .

  The log information storage unit 104 determines that the first control information stored in the variable “oldv” matches the third control information stored in the storage area buffer [myLSN] (in step S149). YES), the second control information stored in the variable “newv” is recorded in the storage area buffer [myLSN] (step S151).

  When the third control information stored in the storage area buffer [myLSN] does not match the first control information stored in the variable “oldv” (NO in step S149). ), The third control information recorded in the storage area buffer [myLSN] is stored in the variable “oldv” (step S150). Thereafter, the log information storage unit 104 executes the processes shown in steps S145 to S149.

  That is, the processes shown in step S149 and step S150 are executed atomically in the same way as the process executed by the “cas” instruction.

  Next, the log information storage unit 104 updates the reachable position information stored in the log buffer information storage unit 111 when the reachable information read in step S145 is in a reachable state (described later). ) To the reachable position information update unit 105. For example, the log information storage unit 104 instructs the update position information update unit 105 to perform an update operation by outputting the second head information to the reachable position information update unit 105. The log information storage unit 104 performs an update operation for updating the reachable position information stored in the log buffer information storage unit 111 when the reachable information read in step S145 is not in a reachable state. Do not instruct 105.

  More specifically, the log information storage unit 104 reads the reachable information stored in the variable “myTurn” and determines whether or not the read reachable information is in a reachable state (step S152). When the reachable information is in a reachable state (YES in step S152), the log information storage unit 104 sends the second head information stored in the variable “nextLSN” to the reachable position information update unit 105. To output to the reachable position information update unit 105 (step S153). In other words, the log information storage unit 104 instructs the reachable position information update unit 105 to update the reachable position information stored in the variable “ReachableUpTo”. On the other hand, when the reachable information is not in a reachable state (NO in step S152), log information storage unit 104 does not instruct reachable position information update unit 105 for an update operation related to reachable position information. .

  Next, the log information storage unit 104 records the log information stored in the storage area starting from the input first position information in the storage area starting from the input first head information in the log buffer 112. . More specifically, the log information storage unit 104 stores the log information stored in the storage area indicated by the position information stored in the variable “myLog” in the storage area buffer [myLSN] in the variable “myLength”. Only the size of the value being recorded is recorded (step S154).

  The process subsequent to step S154 will be described in detail with reference to FIG. FIG. 11 is a flowchart (2/3) illustrating the flow of processing in the log processing unit 102 according to the first embodiment.

  The log buffer information storage unit 111 includes, in the log buffer 112, a log information set recorded in a storage area represented by the input first head information, and control information (hereinafter referred to as “first information”) included in the log information set. 4 control information ”). More specifically, the log information storage unit 104 reads the log information set from the storage area buffer [myLSN] pointed to by the first head information stored in the variable “myLSN”, and the fourth control information in the read log information set Is stored in the variable “oldv” (step S160).

  Next, the log buffer information storage unit 111 reads the recording operation completion information stored in the read fourth control information. More specifically, the log information storage unit 104 reads the recording operation completion information from the variable “cflag” included in the variable “oldv” (step S161), and reads the recorded recording operation completion information, for example, the variable “myTurn”. (Step S162).

  Next, the log information storage unit 104 displays control information (hereinafter referred to as “fifth control information”) including an unreachable state, a completed state, a non-processing state, and size information stored in the third control information. ). More specifically, the log information storage unit 104 stores the control information stored in the variable “oldv” in the variable “newv” (step S163). The log information storage unit 104 stores a non-processing state (for example, 0) indicating that processing is not in progress in the variable “inCopy” in the variable “newv” (step S164), and the variable “cfflag” in the variable “newv”. The completion state (for example, 0) indicating the completion is stored (step S165). Furthermore, the log information storage unit 104 stores an unreachable state (for example, 0) indicating that it is not a reachable state in the variable “rflag” in the variable “newv” (step S166).

  Next, the log information storage unit 104 records the fifth control information in the storage area indicated by the input first head information by executing a process similar to the process executed by the “cas” instruction.

  The process for recording the fifth control information will be described in detail. The log information storage unit 104 reads the control information (hereinafter referred to as “sixth control information”) in the log information set recorded in the storage area represented by the input first head information, and the read sixth control information and Then, it is determined whether or not the fourth control information matches.

  When the sixth control information matches the fourth control information, the log information storage unit 104 records the fifth control information in the storage area represented by the input first head information. That is, in this case, the log information storage unit 104 includes information indicating that the state is not reachable, completion state, information indicating that recording operation is not being performed, and the size indicated by the size information of the input log information. Control information is recorded in a storage area in which the log information set is stored.

  When the sixth control information does not match the fourth control information, the log information storage unit 104 sets the read sixth control information as the fourth control information, and then reads the recording operation completion information, Then, a process of comparing the sixth control information with the fourth control information is executed. That is, the log information storage unit 104 repeats the process until the created control information is recorded in the storage area represented by the input first head information.

  The log information storage unit 104 atomically executes the same process as that executed by the “cas” instruction as described above.

  More specifically, a process for executing the same process as that executed by the “cas” instruction will be described. The log information storage unit 104 determines whether or not the fourth control information stored in the variable “oldv” matches the sixth control information stored in the storage area buffer [myLSN] (step S167). . When the sixth control information stored in the storage area buffer [myLSN] matches the fourth control information stored in the variable “oldv” (YES in step S167), the log information storage unit 104 The fifth control information stored in the variable “newv” is recorded in the storage area buffer [myLSN] (step S169).

  When the sixth control information stored in the storage area buffer [myLSN] does not match the fourth control information stored in the variable “oldv” (NO in step S167), the log information storage unit 104 The sixth control information stored in the storage area buffer [myLSN] is stored in the variable “oldv” (step S168). Thereafter, the log information storage unit 104 executes the processes shown in steps S162 to S167.

  The log information storage unit 104 atomically executes the same process as that executed by the “cas” instruction as described above.

  Next, the log information storage unit 104 updates the completion position information in the log buffer information storage unit 111 (described later) when the recording operation completion information read in step S162 is in an incomplete state indicating completion. ) To the completion position information update unit 106. The log information storage unit 104 instructs the update operation to the completion position information update unit 106 by outputting the second head information to the completion position information update unit 106, for example. The log information storage unit 104 does not instruct the completion position information update unit 106 to perform an update operation for updating the completion position information when the recording operation completion information read in step S162 is not in an incomplete state.

  More specifically, the log information storage unit 104 reads the recording operation completion information stored in the variable “myTurn” and determines whether or not the read recording operation completion information is in an incomplete state (step S170). ). When the recording operation completion information is in an incomplete state (YES in step S170), the log information storage unit 104 sends the second head information stored in the variable “nextLSN” to the completion position information update unit 106. To output to the completion position information update unit 106 (step S171). That is, the log information storage unit 104 instructs the completion position information update unit 106 to update the completion position information stored in the variable “FinishedUpTo”. If the recording operation completion information is not in an incomplete state (NO in step S170), the log information storage unit 104 does not instruct a process for updating the completion position information.

  Next, a process subsequent to step S170 (or step S171) will be described in detail with reference to FIG. FIG. 12 is a flowchart (3/3) illustrating the flow of processing in the log processing unit 102 according to the first embodiment.

  The log information storage unit 104 reads the reachable position information from the log buffer information storage unit 111, and compares the read reachable position information with the second head information calculated in step S141 (FIG. 10). When the read reachable position information is less than the second head information, the log information storage unit 104 until the reachable position information stored in the log buffer information storage unit 111 becomes equal to or more than the second head information. Execute the waiting process.

  More specifically, the log information storage unit 104 reads the reachable position information stored in the variable “ReachableUpTo” in the log buffer information storage unit 111, and stores the read reachable position information and the variable “nextLSN”. The second head information is compared (step S181). When the reachable position information is less than the second head information (NO in step S181), the log information storage unit 104 stores the reachable position stored in the variable “ReachableUpTo” in the log buffer information storage unit 111. A process of waiting until the information reaches the second head information or more is executed (step S182). For example, the waiting process executed by the log information storage unit 104 can be realized by using a “Sleep” function with the value in the variable “nextLSN” as an input.

  The process executed by the reachable position information update unit 105 will be described with reference to FIG. FIG. 13 is a flowchart showing processing in the reachable position information update unit 105 according to the first embodiment.

  The reachable position information update unit 105 inputs the second head information and stores the input second head information in the memory 108 (hereinafter referred to as “first area”). The reachable position information update unit 105 reads a value stored in the memory 108 and stores the read value in the log buffer information storage unit 111 as reachable position information. More specifically, the reachable position information update unit 105 inputs the second head information output from the log information storage unit 104, and stores the input second head information in a variable “nextLSN”. The reachable position information update unit 105 stores the second head information stored in the variable “nextLSN” in the variable “lsn” (step S191). The reachable position information update unit 105 stores the value stored in the variable “lsn” in the variable “ReachableUpTo” in the log buffer information storage unit 111 (step S192).

  Next, the reachable position information update unit 105 in the log buffer 112, the log information set stored in the storage area indicated by the value stored in the first area, and the control information (hereinafter referred to as the log information set). , Expressed as “seventh control information”). More specifically, the reachable position information update unit 105 reads the control information recorded in the storage area buffer [lsn] indicated by the value stored in the variable “lsn” (step S193). The reachable position information update unit 105 stores the seventh control information included in the read log information set in the variable “oldv” (step S194).

  Next, the reachable position information update unit 105 determines whether or not the size in the size information included in the read seventh control information is zero. When the size is not 0, the reachable location information update unit 105 adds the size included in the seventh control information to the value stored in the first area, and calculates the calculated value as the first value. Store in the area. Thereafter, the processing is repeatedly executed until the size represented by the size information included in the control information becomes zero. On the other hand, the reachable position information update unit 105, when the size is 0, the reachable state indicating that the process has not started yet, the recording operation completion information included in the seventh control information Then, control information including the recording operation state information included in the seventh control information and the size information included in the seventh control information (hereinafter referred to as “eighth control information”) is created. In this case, the eighth control information created in step S197 and step S198 is a process in which the process shown in step S195 is executed, and therefore includes 0 as size information.

  More specifically, the reachable position information update unit 105 determines whether the size stored in the variable “length” included in the seventh control information stored in the variable “oldv” is zero. (Step S195). When the size is not 0 (NO in step S195), the reachable position information update unit 105 adds the value stored in the variable “lsn” and the value stored in the variable “length”. The calculated result is stored in the variable “lsn” (step S196). Thereafter, the reachable position information update unit 105 executes the process shown in step S192. On the other hand, when the size is 0 (YES in step S195), the reachable position information update unit 105 sets the seventh control information stored in the variable “oldv” to the variable “newv”. Further, the reachable state indicating that the process has not yet been started is stored in the variable “newv” as the value of reachable information (step S198). The variable “newv” stores the eighth control information by the processing shown in steps S197 and S198.

  The reachable position information update unit 105 executes a process similar to the process executed by the “cas” instruction, and thus the created eighth control information is a value stored in the first area in the log buffer 112. Is recorded in the storage area indicated by.

  A process for recording the eighth control information in the log buffer 112 in the storage area indicated by the value stored in the first area will be described in detail. The reachable position information update unit 105 reads control information (hereinafter, “9th control information”) stored in the storage area indicated by the value stored in the first area in the log buffer 112. The reachable position information update unit 105 stores the created eighth control information in the first area in the log buffer 112 when the read ninth control information matches the read seventh control information. Is recorded in the storage area indicated by the value. When the read 9th control information and the read 7th control information do not match, the reachable position information update unit 105 determines whether or not the size in the size information included in the 7th control information is 0. Process "or" determine whether the ninth control information and the seventh control information match "is executed.

  The reachable position information update unit 105 atomically executes the same process as that executed by the “cas” instruction as described above.

  More specifically, the reachable position information update unit 105 reads the ninth control information stored in the storage area buffer [lsn], and reads the ninth control information read and the first control information stored in the variable “oldv”. 7 Control information is compared (step S199). When the seventh control information stored in the variable “oldv” matches the ninth control information (YES in step S199), the reachable position information update unit 105 stores the variable in “newv”. The eighth control information is recorded in the storage area buffer [lsn] (step S201). When the seventh control information stored in the variable “oldv” does not match the ninth control information (NO in step S199), the reachable position information update unit 105 stores the information in the storage area buffer [lsn]. The stored ninth control information is stored in the variable “oldv” (step S200). After that, the reachable position information update unit 105 executes the process shown in step S195. The log information storage unit 104 atomically executes the same process as that executed by the “cas” instruction as described above.

  Next, the processing subsequent to step S201 will be described in detail with reference to FIG. FIG. 14 is a flowchart showing a flow of processing in the reachable position information update unit 105 according to the first embodiment.

  The reachable position information update unit 105 compares the value stored in the first area with the reachable position information in the log buffer information storage unit 111. The reachable position information update unit 105 executes an instruction to end the waiting process for the log information storage unit 104 that stores a value smaller than the reachable position information in the first area. The reachable position information update unit 105 that has received the instruction ends the waiting process.

  More specifically, the reachable position information update unit 105 executes a process similar to the process in the “WakeUp” function, for example. The reachable position information update unit 105 reads a value from the variable “lsn”, and compares the read value with the reachable position information in the log buffer information storage unit 111. The reachable position information update unit 105 specifies a log information storage unit whose read value is less than the reachable position information, and executes an instruction to end the waiting process in the specified log information storage unit (step S211). The log information storage unit that has received the instruction ends the waiting process.

  With reference to FIG. 15, the process executed by the completed position information update unit 106 will be described. FIG. 15 is a flowchart showing processing in the completed position information update unit 106 according to the first embodiment.

  The completion position information updating unit 106 inputs the second head information and stores the input second head information in the memory 108 (hereinafter referred to as “second area”). More specifically, the completion position information update unit 106 inputs the second head information output from the log information storage unit 104, and stores the input second head information in a variable “nextLSN”. The completion position information update unit 106 stores the second head information stored in the variable “nextLSN” in the variable “lsn” (step S221).

  Next, the completion position information update unit 106 stores the value stored in the second area in the log buffer information storage unit 111 as completion position information. More specifically, the completion position information update unit 106 stores the value stored in the variable “lsn” in the variable “FinishedUpTo” in the log buffer information storage unit 111 (step S222).

  Next, the completion position information update unit 106 reads control information (hereinafter referred to as “tenth control information”) stored in the storage area indicated by the value stored in the second area in the log buffer 112. . The reachable position information update unit 105 determines whether or not the size information included in the read tenth control information is 0, and the recording operation state information in the tenth control information is in the process state. Whether or not is determined.

  The completion position information update unit 106 reads the tenth control information read to the value stored in the first area when the size is not 0 and the recording operation state information is in a non-processing state. The size contained in is added.

  When the size is 0 or the recording operation state information is in the processing state, the completion position information update unit 106 includes control information including the following four pieces of information (hereinafter “11th control information”). ).

-Reachable information included in the tenth control information,
・ Incomplete status indicating the status before processing is completed
Recording operation state information included in the tenth control information,
Control information including size information included in the tenth control information.

  More specifically, the completion position information update unit 106 reads the control information recorded in the storage area buffer [lsn] indicated by the value stored in the variable “lsn” (step S223). The completion position information update unit 106 stores the tenth control information included in the read control information in the variable “oldv” (step S224). The reachable position information update unit 105 executes at least one of the following determination processes 1 and 2 (step S225).

Determination process 1: Whether or not the size stored in the variable “length” included in the tenth control information stored in the variable “oldv” is 0,
Determination process 2: Whether or not the variable “inCopy” included in the tenth control information stored in the variable “oldv” is in the processing state.

  The reachable position information update unit 105 determines that the size stored in the variable “length” is not 0 and the value stored in the variable “inCopy” is in a non-processing state (in step S225). NO), the value stored in the variable “lsn” and the value stored in the variable “length” included in the variable “oldv” are added (step S226). The reachable position information update unit 105 stores the calculated result in the variable “lsn”. Thereafter, the reachable position information update unit 105 executes the process shown in step S222.

  The reachable position information updating unit 105 determines that the size stored in the variable “length” is 0 or the value stored in the variable “inCopy” is in the process state (in step S225). YES), the tenth control information stored in the variable “oldv” is stored in the variable “newv” (step S227). The reachable position information update unit 105 stores 1 (that is, an incomplete state) in a variable “cflag” included in the variable “newv” (step S228). That is, the variable “newv” stores the eleventh control information.

  Next, the completion position information update unit 106 stores the created eleventh control information in the second area in the log buffer 112 by executing a process similar to the process executed by the “cas” instruction. Is recorded in the storage area indicated by the current value.

  The process for recording the eleventh control information will be described in detail. The completion position information update unit 106 reads control information (hereinafter referred to as “twelfth control information”) stored in the value stored in the second area in the log buffer 112. When the read twelfth control information matches the tenth control information, the completion position information update unit 106 displays the created eleventh control information in the log buffer 112 with the value stored in the second area. Record in the indicated storage area. The completion position information update unit 106 sets the twelfth control information to the tenth control information when the read twelfth control information does not match the tenth control information, and then determines the above-described determination regarding the tenth control information. Execute the process.

  The completion position information update unit 106 atomically executes the same process as that executed by the “cas” instruction as described above. More specifically, a process for executing the same process as that executed by the “cas” instruction will be described.

  The completion position information update unit 106 reads the twelfth control information stored in the storage area buffer [lsn]. When the read twelfth control information matches the tenth control information (YES in step S229), the completion position information update unit 106 stores the eleventh control information stored in the variable “newv” in the storage area. It is recorded in buffer [lsn] (step S231). When the read twelfth control information does not match the tenth control information (NO in step S229), the completion position information update unit 106 stores the twelfth control information stored in the storage area buffer [lsn]. It is stored in the variable “oldv” (step S230). Thereafter, the completion position information update unit 106 executes the process shown in step S225.

  The completion position information update unit 106 atomically executes the same process as that executed by the “cas” instruction as described above.

  That is, the completion position information update unit 106 performs the processing shown in FIG. 15, so that in the log information set included in the log buffer 112, the size of the log information set is 0, or the in-process state Look for a log information set that is. In other words, the reachable location information update unit 105 is a log information set that is in the process of log information sets having identifiers larger than the log information set being processed, or the size is still zero. Find log information set. The reachable position information update unit 105 sets an incomplete state (or 1) to the control information included in the found log information set. That is, the reachable position information update unit 105 is a log information set whose identifier is larger than that of the log information set being processed, that is still in processing or whose size is still 0. Is set to an incomplete state (that is, it indicates that it is before completion).

  Next, effects related to the database management apparatus 101 according to the first embodiment will be described.

  According to the database management apparatus 101 according to the present embodiment, control information that enables processing requests to the log buffer 112 to be processed in a short time can be efficiently set in the storage area. This is because it is not necessary for the log processing unit 102 to execute an operation for setting the size in the log buffer 112 during the period in which the process is executed within the period in which the exclusive control right is possessed.

  The reason why the above-described effect is achieved will be described in more detail.

  In the operation of allocating the log buffer 112 by the database management apparatus 101 according to the present embodiment, the operation to be executed within the acquired exclusive control right reads the variable “TAIL” related to the log buffer 112, and then Just update.

  On the other hand, operations that need to be executed within the period when the device described in Non-Patent Document 1 has the exclusive control right, include control information in the log buffer in addition to the processing related to the variable “TAIL”. There are a process for setting size information regarding size and a process for setting recording operation state information.

  Furthermore, the apparatus described in Non-Patent Document 1 securely stores data in a database by completing processing related to a transaction after recording log information in a log buffer. Therefore, in this apparatus, particularly when the information system is a system (many core system) equipped with a large number of cores, contention occurs as a result of a plurality of processes executing operations for securing a log buffer at the same time. As a result, the processing performance of the many-core system decreases.

  Therefore, when comparing the database management device 101 and the device described in Non-Patent Document 1, the processing executed within the period during which the exclusive control right is given is that the database management device 101 performs the processing for the log buffer 112. Less for processing. That is, since the processing amount to be executed within the acquired exclusive control right is small, the database management apparatus 101 according to the present embodiment reduces contention regarding the exclusive control in the many-core system, for example. can do.

Further, the apparatus disclosed in Non-Patent Document 2 has a problem that the control related to the log buffer in the system is more complicated than the database management apparatus 101 according to the present embodiment. There are two reasons for this, for example. That is,
○ When there are a plurality of log buffers 112 to be managed, each process needs to select a log buffer 112 as a write destination.
○ When there are a plurality of targets for determining whether or not the recording process for log information is completed (that is, the log buffer 112), in the data recovery operation after the failure occurs, the log information written in each log buffer 112 It becomes necessary to recognize the order and read the log information according to the order.

  Therefore, according to the database management apparatus 101 according to the present embodiment, it is not necessary to execute complicated control.

  For example, the log buffer 112 can be realized by using a non-volatile memory for log information representing a change history related to a database. In this case, according to the database management apparatus 101 according to the present embodiment, it is not necessary to record the change history on a device such as a disk or SSD that requires input / output operations while synchronizing with the occurrence of the change history. . In addition, according to the database management apparatus 101 according to the present embodiment, it is possible to execute log information recording at high speed, particularly in a many-core system having a large number of cores.

  According to the recording operation completion information in the database management apparatus 101 according to the present embodiment, it is possible to determine in a short time whether or not the processing related to the log information set in the log buffer 112 is before completion. This is because the control information includes recording operation completion information indicating whether or not the process is completed. Since the control information includes the recording operation completion information, the database management apparatus 101 refers to the recording operation completion information in a certain log information set to determine whether the input / output processing has been completed for the certain log information set in a short time. Can be judged in between.

  According to the reachable position information in the database management apparatus 101 according to the present embodiment, it is possible to know in a short time up to which log information set the log buffer 112 has started processing. This is because the reachable position information update unit 105 can identify the position of the log information set that is located in the last order among the log information sets in the reachable state.

  Further, according to the reachable position information in the database management apparatus 101 according to the present embodiment, all the processes for recording the log information set can be surely executed. This is because the waiting process is executed until the processes related to all the log information sets are started based on the position specified by the reachable position information update unit 105. That is, the log processing unit 102 executes the synchronization process at the timing when all the processes related to the log information set are started. Therefore, according to the database management apparatus 101 according to the present embodiment, the next processing can be executed earlier than when the synchronization processing is executed at the timing when all the processing related to the log information set is completed. .

  Further, according to the completion position information in the database management apparatus 101 according to the present embodiment, it is possible to know in a short time whether or not up to which log information set is in the state before the processing is completed in the log buffer 112. it can. This is because the completion position information update unit 106 identifies the position where the control information whose size stored in the variable “length” is 0 is recorded.

  Further, by realizing the log buffer information storage unit 111 in the memory 108 that can be referred to by a plurality of transaction execution units, the processing can be executed more efficiently. This is because a plurality of transaction execution units can refer to the positions stored in the memory 108. The plurality of transaction execution units can refer to the position without executing communication processing with each other. Furthermore, according to the database management apparatus 101 according to the present embodiment, as the processing performance of the memory 108 is higher, the position can be referred to in a shorter time.

<Second Embodiment>
The configuration of the control information setting device 151 according to the second embodiment of the present invention will be described in detail with reference to FIG. FIG. 16 is a block diagram showing the configuration of the control information setting device 151 according to the second embodiment of the present invention.

  The control information setting device 151 according to the second embodiment includes a reachable information setting unit 152 and a log buffer 153.

  As described with reference to FIG. 2, the log buffer 153 has a logical space for storing a log information set in which log information is associated with control information referred to when processing related to the log information is executed. Are in order (ie, logically ordered). The control information includes reachability information that indicates whether or not it is possible to refer to log information sets that are located in order, and size information that indicates the size (size, size) of the log information. To do.

  For convenience of explanation, in the log buffer 153, an area to which processing relating to log information has been assigned (hereinafter referred to as “first area”) and an area to which no processing relating to log information has been assigned (hereinafter referred to as “second area”) Are represented).

  Next, processing in the control information setting device 151 according to the second embodiment will be described with reference to FIG. FIG. 17 is a flowchart showing a flow of processing in the control information setting device 151 according to the second embodiment.

  The reachable information setting unit 152 inputs the boundary value between the first area and the second area, the size of the log information output by the external device, and the log information, for example. The reachable information setting unit 152 controls the control information (hereinafter referred to as “first control area”) recorded in the storage area (hereinafter referred to as “first storage area”) indicated by the input boundary value in the log buffer 153. Information ”) (step S241). The reachable information setting unit 152 sets an unreachable state indicating that it is impossible to refer to the log information set positioned in the subsequent order in the control information recorded in the first storage area (step S1). S242). The reachable information setting unit 152 sets the input size as size information for the control information recorded in the first storage area (step S243).

  The reachable information setting unit 152 determines whether or not the reachable information included in the read first control information is in a reachable state (step S244). When the reachable information is in a reachable state (YES in step S244), the reachable information setting unit 152 stores the size information included in the control information in the log buffer 153 according to the order related to the log information set. Second control information that satisfies a predetermined condition is specified (step S245). For example, the predetermined condition is whether or not the size information is zero. For example, the reachable information setting unit 152 specifies the second control information from the control information subsequent to the first control information in the process shown in step S245. In the storage area having the logical order, the position where the control information following the first control information is recorded is, for example, the position stored in the variable “nextLSN” in the first embodiment.

  The reachable information setting unit 152 sets a reachable state in the reachable information included in the specified second control information (step S246).

  On the other hand, when the reachable information included in the read first control information is in an unreachable state (NO in step S244), the reachable information setting unit 152 proceeds to step S245 and step S246. Do not perform the indicated process.

  The boundary value is, for example, head position information stored in the log buffer information storage unit 111 (FIG. 4) shown in the first embodiment. The reachable information setting unit 152 can be realized by the function of the log information storage unit 104 (FIG. 1) described above, for example.

  Next, effects related to the control information setting device 151 according to the second embodiment will be described.

  According to the control information setting device 151 according to the present embodiment, control information that enables processing requests to the log buffer 153 to be processed in a short time can be efficiently set in the storage area. This is because the process of setting the size in the log buffer 153 can be realized using the reachable information during a period when the exclusive control right for the log buffer 153 is not provided.

  On the other hand, for example, the device disclosed in Non-Patent Document 1 has exclusive control over the size information in the control information in the log buffer shared by a plurality of transaction execution units. Set within a certain period. As a result, according to the control information setting device 151 according to the second embodiment, the processing amount to be processed within the period during which the exclusive control right is held decreases. Therefore, according to the control information setting device 151 according to the present embodiment, it is possible to set control information that enables processing requests to be processed in a short time.

(Hardware configuration example)
A configuration example of hardware resources that implements the database management apparatus according to each embodiment of the present invention described above using one calculation processing apparatus (information processing apparatus, computer) will be described. However, the database management apparatus may be realized using at least two calculation processing apparatuses physically or functionally. Further, such a database management apparatus may be realized as a dedicated apparatus.

  FIG. 18 is a diagram schematically illustrating a hardware configuration example of a calculation processing apparatus capable of realizing the database management apparatus according to the first embodiment and the control information setting apparatus according to the second embodiment. The calculation processing device 20 includes a central processing unit (Central_Processing_Unit, hereinafter referred to as “CPU”) 21, a memory 22, a disk 23, a nonvolatile recording medium 24, a communication interface (hereinafter, referred to as “communication IF”) 27, And a display 28. The calculation processing device 20 may further include an input device 25 and an output device 26. The calculation processing device 20 can transmit / receive information to / from other calculation processing devices and communication devices via the communication IF 27.

  The nonvolatile recording medium 24 is, for example, a compact disk (Compact_Disc) or a digital versatile disk (Digital_Versatile_Disc) that can be read by a computer. The nonvolatile recording medium 24 may be a universal serial bus memory (USB memory), a solid state drive (Solid_State_Drive), or the like. The non-volatile recording medium 24 retains such a program without being supplied with power, and can be carried. The nonvolatile recording medium 24 is not limited to the above-described medium. Further, the program may be carried via the communication IF 27 and the communication network instead of the nonvolatile recording medium 24.

  That is, the CPU 21 copies a software program (computer program: hereinafter simply referred to as “program”) stored in the disk 23 to the memory 22 when executing it, and executes arithmetic processing. The CPU 21 reads data necessary for program execution from the memory 22. When the display is necessary, the CPU 21 displays the output result on the display 28. When output to the outside is necessary, the CPU 21 outputs an output result to the output device 26. When inputting a program from the outside, the CPU 21 reads the program from the input device 25. The CPU 21 controls the database management program (FIGS. 5, 6, 8 to 15) in the memory 22 corresponding to the function (process) represented by each unit shown in FIG. 1 or FIG. The information setting program (FIG. 17) is interpreted and executed. The CPU 21 sequentially executes the processes described in the above embodiments of the present invention.

  That is, in such a case, it can be understood that the present invention can also be realized by the control information setting program or the database management program. Furthermore, it can be understood that the present invention can also be realized by such a database management program or a computer-readable non-volatile recording medium in which the control information setting program is recorded.

  The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above-described embodiment. That is, the present invention can apply various modes that can be understood by those skilled in the art within the scope of the present invention.

DESCRIPTION OF SYMBOLS 101 Database management apparatus 102 Log processing part 103 Head position calculation part 104 Log information storage part 105 Reachable position information update part 106 Completion position information update part 107 Transaction execution part 108 Memory 109 Transaction execution part 110 Transaction execution part 111 Log buffer information storage Unit 112 log buffer 151 control information setting device 152 reachable information setting unit 153 log buffer 20 calculation processing device 21 CPU
22 Memory 23 Disk 24 Non-volatile recording medium 25 Input device 26 Output device 27 Communication IF
28 Display

Claims (10)

Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to A log buffer in which storage areas that can be stored in association with control information including size information indicating the size of the log information and the reachable information indicating the size of the log information are logically arranged in the order;
In the log buffer, the first control information recorded in a storage area that represents a boundary between a storage area to which the recording process for recording the log information has been assigned and a storage area to which the recording process is not assigned is enabled from the first control information. Read information, set the unreachable state in the reachable information included in the first control information, set the size in the size information included in the first control information, and read When the reachable information is in the reachable state, second control information indicating that the size information satisfies a predetermined condition is specified according to the order in the log buffer, and the specified second control information A control information setting device comprising: reachability information setting means for setting the included reachability information to the reachable state. The control information is further in a processing state indicating a state in which the processing for storing the log information is being executed, or is in a non-processing state indicating a state in which the processing for storing the log information is not being executed. Recording operation status information indicating whether or not
When the process of setting the in-process state to the recording operation state information included in the first control information and recording the log information related to the first control information in the log buffer is completed, The control information setting device according to claim 1, further comprising log information storage means for setting the non-processing state in the recording operation state information included in the first control information. The control information further indicates whether the processing for storing the log information is in an incomplete state indicating a state before completion or whether the processing for storing the log information is completed. Including recording operation completion information,
The log information storage means records the certain size of log information in the first storage area, and then, from the second control information stored in the first storage area represented by the read boundary value, the recording operation In the log buffer, the size information satisfies the predetermined condition in accordance with the order in the log buffer, or the recording operation is performed when the recording operation completion information read is in the incomplete state. The third control information indicating that the state information is the processing state is specified, and the completion state is set in the recording operation completion information included in the specified third control information. Control information setting device. The log buffer further comprises a reachable position information update means for specifying a position where the second control information is recorded,
The control information setting device according to claim 3, wherein the log information storage unit performs a waiting process until the position is equal to or greater than a value obtained by adding the boundary and the certain size. 5. The control information setting device according to claim 3, further comprising: a completion position update unit that specifies a position where the third control information is recorded in the log buffer. A plurality of log information storage means including an input / output memory;
The control information setting device according to claim 4, wherein the reachable position information update unit stores the specified position in the memory. The control information setting device according to any one of claims 1 to 6, wherein the log buffer is a storage area in a nonvolatile recording medium.   Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to A data structure in which the space for storing the information in a state in which the reachable information indicating the size and the control information including the size information indicating the size of the log information are associated with each other is logically arranged in the order. Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to And a log buffer in which storage areas that can be stored in association with control information including size information indicating the size of the log information are logically arranged in the order.
In the log buffer, the first control information recorded in a storage area that represents a boundary between a storage area to which the recording process for recording the log information has been assigned and a storage area to which the recording process is not assigned is enabled from the first control information. Read information, set the unreachable state in the reachable information included in the first control information, set the size in the size information included in the first control information, and read When the reachable information is in the reachable state, second control information indicating that the size information satisfies a predetermined condition is specified according to the order in the log buffer, and the specified second control information A control information setting method for setting the included reachability information to the reachable state. Whether the log information is in a reachable state indicating that it is possible to refer to the log information that follows the log information in a predetermined order, or is an unreachable state indicating a state in which it cannot be referred to And a log buffer in which storage areas that can be stored in association with control information including size information indicating the size of the log information are logically arranged in the order.
In the log buffer, the first control information recorded in a storage area that represents a boundary between a storage area to which the recording process for recording the log information has been assigned and a storage area to which the recording process is not assigned is enabled from the first control information. Read information, set the unreachable state in the reachable information included in the first control information, set the size in the size information included in the first control information, and read When the reachable information is in the reachable state, second control information indicating that the size information satisfies a predetermined condition is specified according to the order in the log buffer, and the specified second control information A database management program for causing a computer to realize a reachable information setting function for setting the reachable information included in the reachable state.

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