Data storage system and data storage method

Abstract

This invention provides a data storage system and a data storage method. The data storage system includes a data reading unit and a data storage unit. The data reading unit receives data reading requests. The data reading unit obtains a hash value from the data reading request according to a hash algorithm. The data reading unit obtains a hash element with the corresponding hash offset from the hash array according to the hash value. The data reading unit uses the hash element as the offset of the element array. The data reading unit obtains element data with the corresponding offset from the element array according to the offset. During the data storage process, the data storage unit determines whether a hash element is stored at the corresponding position in the hash array based on the hash value. In response to the determination result that no hash element is stored, the data storage unit stores the element data in the empty position with the smallest offset in the element array, and stores the offset of the empty position in the storage position.

Description

Data storage system and data storage method The present invention relates to a data storage technology and a storage structure, and in particular to a data storage system and a data storage method. In traditional data storage structures, the data mapping process refers to the process of searching for data one by one and filling it into the target structure according to the storage logic and storage order during the storage of complex data. During the data storage / construction stage, the system needs to convert the data structure into an ordered list structure through complex logical processing, which is not only time-consuming and occupies high computing resources, but also occupies a lot of memory space. At the same time, during the data acquisition / reading stage, the system needs to traverse the list data from the beginning or continue to traverse the search from the location that has been traversed. Therefore, the computing resources consumed by the system traversal search will increase with the increase in data volume, which makes the data processing efficiency of the system's data mapping extremely low and consumes too many computing resources. The present invention is directed to a data storage system and a data storage method, which can realize the function and structure of saving memory space while storing data in an orderly manner. According to an embodiment of the present invention, a data storage system includes a data reading unit. The data reading unit is configured to receive a data read request. The data reading unit obtains a hash value from the data read request according to a hash algorithm. The data reading unit obtains a hash element corresponding to a hash offset from a hash array based on the hash value. The data reading unit uses the hash element as an offset into an element array. The data reading unit obtains element data corresponding to the offset from the element array based on the offset. According to an embodiment of the present invention, a data storage method of the present invention includes the following steps: receiving a data read request by a data reading unit; obtaining a hash value from the data read request according to a hash algorithm by the data reading unit; obtaining a hash element corresponding to a hash offset from a hash array according to the hash value by the data reading unit; using the hash element as an offset to an element array by the data reading unit; and obtaining element data corresponding to the offset from the element array according to the offset by the data reading unit. Based on the foregoing, the data storage system and data storage method of the present invention can automatically read data and obtain the storage location of the data in the element array through a hash algorithm in the hash array, thereby effectively storing data in an orderly and low-memory manner through two arrays, effectively avoiding repeated data traversal, thereby improving system operating efficiency and reducing the computational complexity of data storage and reading. In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts. FIG1 is a schematic diagram of a data storage system according to an embodiment of the present invention. Referring to FIG1 , the data storage system 100 includes a data reading unit 110 and a data storage unit 120. The data storage system 100 is coupled to a computer device 200. The data storage system 100 can connect to the computer device 200 via a network. In this embodiment, the computer device 200 can be, for example, a laptop, a desktop, a tablet, a smartphone, or a related electronic device. The computer device 200 can be used to run a business system and can initiate data structure creation requests (i.e., data storage requests) to the data storage system 100 based on user or tenant operations. The business system can be, for example, an Enterprise Resource Planning (ERP) system, a Manufacturing Execution System (MES), a Human Resources Management System (HRMS), or a Financial Management System (FMS), but the present invention is not limited thereto. In this embodiment, the data storage system 100 may be, for example, installed on a server in the cloud or other electronic device with data computing and data storage capabilities. The data storage system 100 may include a processor and a memory. In this embodiment, the processor may be a system on a chip (SOC), or may include, for example, a central processing unit (CPU) or other programmable general-purpose or special-purpose microprocessor, a digital signal processor (DSP), a programmable controller, an application-specific integrated circuit (ASIC), a programmable logic device (PLD), other similar processing devices, or a combination of these devices. In this embodiment, the memory may be, for example, a dynamic random access memory (DRAM), a flash memory, or a non-volatile random access memory (NVRAM). In this embodiment, the memory can be used to store the data reading unit 110 and the construction process management unit 120, so that the processor can read and execute the stored data reading unit 110 and the construction process management unit 120, thereby executing the various steps and functions in the present invention, and the memory can also temporarily store related data, related programs and algorithms required or generated in the data construction process and the data reading process. FIG2 is a flow chart of a data storage method according to an embodiment of the present invention. Referring to FIG2 , the data storage system 100 may execute the following steps S210 to S250 to obtain the element data (i.e., element content) corresponding to the request. In this embodiment, the computer device 200 may send a corresponding data read request to the data storage system 100 based on the operation of the user or tenant, such as executing an application programming interface of a certain service. In step S210, the data reading unit 110 receives the data read request. In step S220, the data reading unit 110 obtains a hash value from the data read request according to a hash algorithm. For example, the data read request includes the key data "name", and the data reading unit 110 passes the key data "name" through a hash algorithm to calculate the corresponding hash value "7". In one embodiment, the data reading unit 110 can retrieve corresponding hash algorithm rules / logic data from a storage device, and then execute the hash algorithm via a processor to convert the key data in the data read request into a hash value. This embodiment is not limited to hash algorithms; any similar one-way cryptographic system can be applied to this embodiment. Furthermore, the corresponding conversion rules (e.g., hash algorithm rules) can be stored locally or in an external storage device. In step S230, the data reading unit 110 obtains a hash element corresponding to a hash offset from the hash array based on the hash value. Specifically, the hash array includes a hash offset and a storage location. The storage location of the hash array is used to store the data location of the element. For example, the hash element corresponding to the hash value "7" in the hash array is "1". It is worth noting that the hash array in the data storage system 100 can be a one-dimensional sequence including a column of values ​​and a certain number (i.e., a hash offset), or it can be a two-dimensional sequence in which a sequence of values ​​(i.e., a hash offset) corresponds to another column of values. In step S240, the data reading unit 110 uses the hash element as an offset to the element array. For example, the data reading unit 110 uses the hash element "1" as the offset to search the element array, and thus sets the offset to "1." Specifically, the element array can be a one-dimensional sequence containing a column of data and a certain number (i.e., an offset), or a two-dimensional sequence in which a sequence of values ​​(i.e., offsets) corresponds to another column of numbers. In step S250, the data reading unit 110 obtains the element data corresponding to the offset from the element array based on the offset. For example, the data reading unit 110 uses the data corresponding to the offset of "1" in the element array as the element data. In one embodiment, the data reading unit 110 uses the data next to the offset of "1" in the element array as the element data. Specifically, the data reading unit 110 finds the corresponding data group in the element array based on the offset and reads the element data in the corresponding data group. In one embodiment, the data group includes key data, element data, and a conflict offset. When the data group is stored in the order of key data, element data, and conflict offset, the data reading unit 110 uses the next data corresponding to the offset of "1" in the element array as the element data. In another embodiment, when the data group is stored in the order of element data, key data, and conflict offset, the data reading unit 110 uses the data (e.g., a value, a field, or a symbol) corresponding to the offset of "1" in the element array as the element data. The present invention should not be limited to this. In one embodiment, the data reading unit 110 reads the corresponding key data in the element array based on the hash value, and the data reading unit 110 compares the key data to the key data in the data read request. If they are not the same, the data reading unit 110 reads the corresponding key data in the element array based on the conflict offset in the current data group until the key data that is the same as the key data in the data read request is found. If they are the same, the data reading unit 110 outputs the key data and the element data as output data to the electronic device that issued the data read request. As a result, the data reading unit 110 does not need to traverse previously read data or the entire data each time it reads data. Therefore, the data storage system 100 of this embodiment can automatically perform high-efficiency data reading based on the settings of the hash array and element array, and can avoid highly complex logical operations to read the corresponding data to obtain the data in the key-value pair, thereby effectively improving the operating efficiency of the data storage system 100, saving computing resources, and effectively saving storage resources. FIG3 is a flow chart of data storage according to an embodiment of the present invention. In various embodiments of the present invention, the data reading unit 110 and the data storage unit 120 may be implemented in programming languages ​​such as JSON (JavaScript Object Notation), Extensible Markup Language (XML), or YAML, respectively, but the present invention is not limited thereto. The data storage system 300 may execute the following steps S310 to S340 to achieve automatic data construction (i.e., data storage). The data storage unit 120 receives a data storage request. In one embodiment, the computer device 200 may, based on the operation of the user or tenant, such as executing an application programming interface of a service, send a corresponding data storage request to the data storage system 100. In step S310, the data storage unit 120 obtains a hash value from the data storage request using a hash algorithm. Specifically, the data storage unit 120 receives the data storage request and performs a hash operation on the key data in the data storage request using a hash algorithm to obtain a corresponding hash value. In step S320, the data storage unit 120 determines whether a hash element is stored in the storage location corresponding to the hash value in the hash array based on the hash value. For example, the data storage unit 120 calculates a hash value "4" from the key data "month_1" through a hash operation. Next, based on the hash value "4," the data storage unit 120 determines whether a hash element is already stored in the storage location corresponding to the hash value "4" (e.g., the fifth storage location) in the hash array. In step S330, in response to the storage location not storing the hash element, the data storage unit 120 stores the element data corresponding to the data storage request in an empty location with the smallest offset in the element array. It is worth noting that the data storage unit 120 may determine that the storage location does not store the hash element, or it may determine that the storage location corresponding to the storage location is an empty location (i.e., no data is stored). In this way, the data storage unit 120 stores the element data in the data storage request in an empty location with the smallest offset (i.e., sequence value) in the element array. In step S340, the data storage unit 120 stores the offset value of the empty position in the corresponding storage location in the hash array. For example, if the empty position with the smallest offset in step S330 corresponds to an offset of "4" in the element array, the data storage unit 120 stores "4" in the storage location in step S320 in the hash array. FIG4 is a schematic diagram of an element array and a hash array according to the present invention. In one embodiment, in response to a hash element already being stored in a storage location, the data storage unit 120 determines whether the conflict offset of the corresponding hash element in the element array 410 is a preset value. Then, in response to the conflict offset being the preset value (e.g., "-1"), the data storage unit 120 stores the element data in the data storage request to the empty location with the smallest offset in the element array. Element array 410 includes an element data column 412 and an offset column 413. Offset column 413 is sequentially arranged from 0 to N, where N is a positive integer. Element data column 412 consists of a null value 411 and multiple data groups, each of which sequentially includes key data (414, 417, 420), element data (415, 418, 421), and conflict offsets (416, 419, 422). Hash array 430 includes a hash element column 431 and a hash offset column 432. For example, if the hash value in step S320 is "6," the data storage unit 120 determines that the element data "4" is already stored in the storage location 433 corresponding to the hash offset of 6 (i.e., the 7th position in the hash offset array 432) in the element array 410. Next, the data storage unit 120 determines whether the value of the conflict offset 419 corresponding to the offset of 4 (i.e., the 5th position in the offset array 413) in the element array 410 is a predetermined value of "-1." If the conflict offset is the predetermined value, the data storage unit 120 stores the element data in the data storage request in the smallest empty location in the element array 410 (e.g., the storage location at offset 10 in the element array). Next, the data storage unit 120 stores the value "10" of the offset of the empty position (e.g., "10") in the collision offset "-1" corresponding to the hash element "4." For example, the data storage unit 120 updates the value of the corresponding collision offset 419 (which is the default value "-1") to the offset "10" of the empty position. On the other hand, in response to the conflict offset being different from the preset value (e.g., "-1"), the data storage unit 120 determines whether the next conflict offset corresponding to the conflict offset (e.g., "7") in the element array 410 (e.g., the conflict offset 422 corresponding to the 7th position in the element array 410 is at the 9th position) is the preset value "-1", and continues until the next conflict offset is the same as the preset value, thereby storing the element data in the data storage request to the empty position with the smallest offset in the element array. It is worth noting that the data storage unit 120 stores the offset value (e.g., "10") of the empty position (e.g., the position with offset "10" in the element array 410) to the next conflict offset that is the same as the preset value (e.g., the conflict offset 422 with offset 9 in the element array 410). In this example, the data storage unit 120 stores the offset 10 of the empty position in the conflict offset 422. In one embodiment, a data storage request includes key data and element data. Element data is the value data in a key-value pair. Furthermore, each set of key data and element data in the element array 410 and the hash array 430, as well as the collision offset, each occupies at least 1 byte. In the existing storage method, only the reference address in a 64-bit device occupies 8 bytes. The difference is that in the data storage system and method of the present application, each set of key data and element data (i.e., each set of key values) only occupies 2 bytes and the size of the key value original data, thereby effectively saving memory space. For example, when each set of key data and element data, as well as the hash element and the collision offset in the element array 410 and the hash array 430, each occupies 1 byte, since 2 to the power of 7 minus 1 divided by 3 (i.e., the hash element corresponding to the element data, key data, and collision offset) is an integer equal to 42, a total of 42 sets of key value data can be stored in this embodiment. In another embodiment, when each set of key data and element data, as well as the hash element and the collision offset in the element array 410 and the hash array 430, each occupies 2 bytes, since 2 to the power of 15 minus 1 divided by 3 is equal to 10922, a total of 10922 sets of key value data can be stored in this embodiment, and so on, and the present invention should not be limited to this. Regarding each set of key data and element data, it means that one key data and one element data constitute a data group. The data group in the element array 410 and the hash array 430 is, for example, the hash element 433, the hash offset "6" corresponding to the hash element 433, the key data 417 "month_1" corresponding to the hash element 433 being "4", the offset "4" corresponding to the key data, the element data 418 "16.3", the offset "5" corresponding to the element data 418, the conflict offset 419, and the offset "6" corresponding to the conflict offset 419. In one embodiment, the element array also includes the latest offset of the latest key data. For example, in FIG4 , the latest key data is key data 420, and the corresponding latest offset is offset "7." Thus, the data storage unit 120 can sequentially store subsequent data sets (i.e., element data and key data) in the element array 410 using the latest offset. In other words, the element array 410 sequentially stores each set of element data and key data. In one embodiment, the step of the data storage unit 120 storing the element data corresponding to the data storage request in the empty position with the smallest offset in the element array includes: the data storage unit 120 sequentially stores the key data and the element data in the position of the element array at the latest offset plus a set value. In this embodiment, the set value is the number of positions occupied by each set of data in the element array 410. In this embodiment, each set of data (i.e., data group) occupies three positions in the element array 410, namely the key data, the element data, and the conflict offset. In this way, the data storage unit 120 can sequentially store the new data group in the position of the latest offset plus 3 (e.g., 7 plus 3 is 10) in the element array 410. In addition, the data storage unit 120 stores a default conflict offset (e.g., "-1") in the position next to the element data (e.g., the position with offset 11) in the element array (e.g., the position with offset 12). In one embodiment, the step of the data reading unit 110 obtaining the element data corresponding to the offset from the element array 410 according to the offset includes: the data reading unit 110 reading the corresponding conflicting offset in the element array according to the offset; the data reading unit 110 determining whether the conflicting offset is the same as a preset value (e.g., "-1"); and in response to the conflicting offset being the preset value, the data reading unit 110 reading the element data corresponding to the offset in the element array. The data reading unit 110 then outputs the corresponding element data to the computer device 200 or the electronic device that issued the data read request. In one embodiment, the step of the data reading unit 110 obtaining a hash value from a data reading request according to a hash algorithm includes: the data reading request includes key data, and then the data reading unit 110 converts the key data (e.g., "month_2") into a hash value (e.g., "7") through the hash algorithm. In another embodiment, the data read request includes a sort value of the element data, which may be a sequential value stored in a plurality of data groups, such as the sort values ​​of the first data group, the second data group, the third data group, etc. The data read unit 110 is further configured to obtain the key data from the element array 410 by multiplying the sort value by a set value and adding the sort value of the key data in each data group (e.g., "1"). Furthermore, the data read unit 110 multiplies the sort value by the set value and adds the sort value of the element data in each data group (e.g., "2") to obtain the corresponding element data from the element array 410. The set value is the number of positions occupied by each group of data in the element array 410. It is worth noting that the step in which the data reading unit 110 obtains element data of corresponding offset from the element array according to the offset also includes: in response to the conflict offset being different from the preset value, the data reading unit 110 repeatedly reads the element data in the element array according to the conflict offset until the key data having the same key data as the data reading request is found in the element array 410, and the value data having the same key data as the data reading request is used as the element data. In summary, the data storage system and data storage method of the present invention can automatically read data and, through a hashing algorithm, determine the data's storage location in the element array. This effectively stores data in both the hash array and the element array, thereby achieving orderly and low-memory data storage. Thus, the data storage system and data storage method of the present invention effectively avoid repeated data traversal, thereby improving system operating efficiency and reducing the computational complexity of data storage and reading. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. 100: Data storage system 110: Data reading unit 120: Data storage unit 200: Computer device 410: Element array 411: Null value 412: Element data array 413: Offset array 414: Key data 415: Element data 416: Conflict offset 417: Key data 418: Element data 419: Conflict offset 420: Key data 421: Element data 422: Conflict offset 430: Hash array 431: Hash element array 432: Hash offset array 433: Storage location 434: Storage location S210-S250, S310-S340: Steps FIG1 is a schematic diagram of a data storage system according to an embodiment of the present invention. FIG2 is a flow chart of a data storage method according to an embodiment of the present invention. FIG3 is a flow chart of performing data storage according to an embodiment of the present invention. FIG4 is a schematic diagram of an element array and a hash array according to an embodiment of the present invention. S210~S250: Steps

Claims

1. A data storage system, comprising: A data reading unit is configured to receive a data reading request. The data reading unit obtains a hash value from the data reading request according to a hash algorithm. The data reading unit obtains a hash element with a corresponding hash offset from a hash array based on the hash value. The data reading unit uses the hash element as an offset in an element array. The data reading unit obtains element data corresponding to the offset from the element array based on the offset. The data reading unit reads a corresponding conflict offset in the element array based on the offset. The data reading unit determines whether the conflict offset is the same as a preset value. If the conflict offset is the preset value, the data reading unit reads the element data corresponding to the offset in the element array. The data reading request includes key data, and the data reading unit converts the key data into the hash value using the hash algorithm.

2. The data storage system as described in claim 1 further includes: A data storage unit is configured to receive a data storage request. The data storage unit obtains the hash value from the data storage request using the hash algorithm. The data storage unit determines whether a hash element is stored at the storage location corresponding to the hash value in the hash array based on the hash value. If the storage location does not store the hash element, the data storage unit stores the element data corresponding to the data storage request in the empty location with the smallest offset in the element array. The data storage unit stores the offset value of the empty location in the corresponding storage location in the hash array.

3. The data storage system as claimed in claim 2, wherein in response to the storage location having the hash element stored, the data storage unit determines whether the conflict offset corresponding to the hash element is a preset value; in response to the conflict offset being the preset value, the data storage unit stores the element data of the data storage request to the empty location with the smallest offset in the element array, wherein the data storage unit stores the value of the offset of the empty location to the conflict offset corresponding to the hash element.

4. The data storage system as described in claim 3, wherein in response to the conflict offset being different from the preset value, the data storage unit determines whether the next conflict offset in the element array corresponding to the conflict offset is the preset value, until the next conflict offset is the same as the preset value, wherein the data storage unit stores the element data of the data storage request in the empty position with the smallest offset in the element array, wherein the data storage unit stores the value of the offset of the empty position in the next conflict offset that is the same as the preset value.

5. The data storage system as claimed in claim 1, wherein in response to the conflict offset being different from the preset value, the data reading unit reads the element data in the element array according to the conflict offset, and uses the value data with the same key data as the data reading request as the element data.

6. The data storage system of claim 1, wherein the data reading unit reads the corresponding key data in the element array according to the hash value, wherein the data reading unit outputs the key data and the element data as output data to the electronic device that issued the data reading request.

7. The data storage system of claim 2, wherein the data storage request includes key data and element data, wherein each set of key data and element data occupies at least one byte for each hash element and collision offset in the element array and the hash array.

8. The data storage system as claimed in claim 2, wherein the data storage request includes the element data and key data, wherein the element array includes the latest offset of the latest key data, wherein the element array stores each group of the element data and the key data in an ordered manner, wherein the data storage unit stores the key data and the element data sequentially in the element array at the position of the latest offset plus a preset value, wherein the preset value is the number of positions occupied by each group of data in the element array, wherein the data storage unit stores a default conflict offset in the next position of the element data in the element array.

9. The data storage system of claim 1, wherein the data read request includes a sort value of the element data, and the data read unit is further configured to obtain key data from the element array by multiplying the sort value by a set value and adding 1, wherein the data read unit multiplies the sort value by the set value and adds 2 to obtain the element data from the element array, wherein the set value is the number of positions occupied by each group of data in the element array.

10. A data storage method, comprising: Receive data read requests through the data read unit; The data reading unit obtains a hash value from the data reading request according to a hash algorithm. The data reading unit obtains the hash element with the corresponding hash offset from the hash array according to the hash value; The data reading unit uses the hash element as an offset of the element array; and the data reading unit obtains element data corresponding to the offset from the element array according to the offset, wherein the step of the data reading unit obtaining element data corresponding to the offset from the element array according to the offset includes: reading the corresponding conflict offset in the element array according to the offset, wherein the data reading unit determines whether the conflict offset is the same as a preset value; and in response to the conflict offset being a preset value, reading the element data corresponding to the offset in the element array; wherein the step of the data reading unit obtaining a hash value from the data reading request according to the hash algorithm includes: the data reading request includes key data, wherein the data reading unit converts the key data into the hash value using the hash algorithm.

11. The data storage method as described in claim 10 further includes: Receive data storage requests through the data storage unit; The hash value is obtained from the data storage request through the hash algorithm by the data storage unit; The data storage unit determines whether a hash element is stored at the storage location corresponding to the hash value in the hash array based on the hash value; in response to the storage location not storing the hash element, the data storage unit stores the element data corresponding to the data storage request to the empty location with the smallest offset in the element array; and the data storage unit stores the value of the offset of the empty location to the storage location corresponding to the hash array.

12. The data storage method as described in claim 11 further includes: In response to the storage location storing the hash element, the data storage unit determines whether the conflict offset corresponding to the hash element is a preset value; In response to the conflict offset being the preset value, the element data of the data storage request is stored in the empty position with the smallest offset in the element array through the data storage unit; and the value of the offset of the empty position is stored in the conflict offset corresponding to the hash element through the data storage unit.

13. The data storage method as described in claim 12 further includes: In response to the conflict offset being different from the preset value, the data storage unit determines whether the next conflict offset in the element array corresponding to the conflict offset is the preset value, until the next conflict offset is the same as the preset value; the data storage unit stores the element data of the data storage request to the empty position with the smallest offset in the element array; and the data storage unit stores the value of the offset of the empty position to the next conflict offset that is the same as the preset value.

14. The data storage method as described in claim 10, wherein the step of obtaining element data corresponding to the offset from the element array by the data reading unit according to the offset further includes: In response to the conflict offset being different from the preset value, the data reading unit reads the element data in the element array according to the conflict offset, and uses the value data with the same key data as the data reading request as the element data.

15. The data storage method as described in claim 10 further includes: The data reading unit reads the corresponding key data in the element array based on the hash value; The key data and the element data are output as output data by the data reading unit and output to the electronic device that issued the data reading request.

16. The data storage method of claim 11, wherein the data storage request includes key data and element data, wherein each set of key data and element data occupies at least one byte for each hash element and collision offset in the element array and the hash array.

17. The data storage method as described in claim 11, wherein the data storage request includes the element data and key data, wherein the element array includes the latest offset of the latest key data, wherein the element array stores each group of the element data and the key data in an ordered manner, and the step of storing the element data corresponding to the data storage request to the empty position with the smallest offset in the element array through the data storage unit includes: The key data and the element data are sequentially stored in the element array at the position of the latest offset plus a set value, wherein the set value is the number of positions occupied by each group of data in the element array; and the default conflict offset is stored in the next position of the element data in the element array by the data storage unit.

18. The data storage method of claim 10, wherein the data read request includes a sort value of the element data; the data read unit is further configured to obtain key data from the element array by multiplying the sort value by a set value and adding 1; and to obtain the element data from the element array by multiplying the sort value by the set value and adding 2, wherein the set value is the number of positions occupied by each group of data in the element array.

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