Multi-version file management method and device suitable for surveying and mapping projects

Abstract

The present invention provides a multi-version file management method and device suitable for surveying and mapping projects, the method comprising: dividing the surveying and mapping file into multiple sub-files according to the hierarchical affiliation principle; grading the sub-files according to the expected update frequency and setting the corresponding level; determining the number of objects in the next level in the sub-file according to the level, so that the number of objects matches the level; grading the next level objects according to the expected update frequency and setting the corresponding object level; determining the number of sub-objects in the next level object according to the level, so that the number of sub-objects matches the object level; returning to determine the number of objects in the next level in the sub-file according to the level until the preset division principle is met; and establishing object indexes for the sub-objects and objects. The storage cost can be effectively reduced, and the consistency of each version of data can be ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of surveying and mapping file management, and in particular relates to a multi-version file management method and device suitable for surveying and mapping projects. Background Art

[0002] Surveying and mapping projects have strict requirements on various project data generated during the project process. The current situation is that project data is generally managed and stored locally by operators. However, due to the rapid development of urbanization, the content of surveying and mapping files is huge, and distributed databases are currently used for storage. With the design of one body and two databases, all operation data are stored and circulated online.

[0003] However, the amount of project data is large, and there are many types of project data. At the same time, all process project data must be saved, and all project data are stored in an incremental manner, and the data volume grows rapidly. Although the use of distributed databases can store a large amount of data, it is still unable to cope with the ever-changing changes in buildings. Although it can be expanded, it also increases the storage cost invisibly. In addition, since the data is constantly updated, it is easy to cause confusion in the original version of the project data, and it is easy to cause version inconsistency when multiple people use it. There are problems such as inconsistency in quality inspection project data and inconsistent versions of results data when delivering results during the quality inspection process. Summary of the invention

[0004] In view of this, the present invention aims to propose a multi-version file management method and device suitable for surveying and mapping projects, so as to solve the technical problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] On the one hand, an embodiment of the present invention provides a multi-version file management method applicable to surveying and mapping projects. It includes:

[0007] Dividing the surveying and mapping file into multiple sub-files according to the hierarchical principle;

[0008] Classifying the sub-files according to the expected update frequency and setting corresponding levels;

[0009] Determine the number of objects in the next level in the subfile according to the level, so that the number of objects matches the level;

[0010] Classifying the next-level objects according to the expected update frequency and setting corresponding object levels;

[0011] Determining the number of sub-objects in the next-level object according to the level so that the number of sub-objects more or less matches the level of the object;

[0012] Returning the number of objects at the next level in the subfile determined according to the level until the preset division principle is met;

[0013] An object index is created for the sub-object and the object.

[0014] Furthermore, the method further comprises:

[0015] Create a level index and create an associated index between the level index and the object index;

[0016] The level index, object index and association index are used as version indexes.

[0017] Furthermore, the method further comprises:

[0018] When a file is modified, the modified content is recorded and a new version number is generated;

[0019] Modify the object index according to the modified content;

[0020] The level index is modified according to the object index.

[0021] Furthermore, the method further comprises:

[0022] When the level changes, the level index is modified according to the changed level;

[0023] Detect whether the object has changed according to the changed level, and modify the object index when the object has changed;

[0024] Modify the associated index between the level index and the object index.

[0025] Furthermore, when the level changes, modifying the level index according to the changed level includes:

[0026] If the high level is changed to a low level, an object classification change is detected, and the level index is modified according to the object classification change.

[0027] Furthermore, when the level changes, the level index is modified according to the changed level.

[0028] include:

[0029] If the low level is changed to a high level, the change in the number of objects corresponding to the changed level is detected and the object index is modified.

[0030] Furthermore, the preset division principles include:

[0031] The number of levels in the object is no more than three and the granularity of the smallest level sub-object is no less than the minimum granularity threshold.

[0032] On the other hand, an embodiment of the present invention further provides a multi-version file management device suitable for surveying and mapping projects, comprising:

[0033] A division module, used for dividing the surveying and mapping file into a plurality of sub-files according to the hierarchical affiliation principle;

[0034] A setting module, used for grading the sub-files according to the expected update frequency and setting the corresponding levels;

[0035] A determination module, configured to determine the number of objects in the next level in the subfile according to the level, so that the number of objects matches the level;

[0036] A grading module, used for grading the objects at the next level according to the expected update frequency and setting the corresponding object level;

[0037] A quantity determination module, used to determine the number of sub-objects in the next-level object according to the level, so that the number of sub-objects more or less matches the level of the object;

[0038] A return module, used for returning the number of objects in the next level in the sub-file determined according to the level until a preset division principle is met;

[0039] A building module is used to build object indexes for the sub-objects and objects.

[0040] Furthermore, the device also includes:

[0041] An index creation module, used to create a level index and create an associated index between the level index and the object index;

[0042] The version index generating module is used to use the level index, object index and association index as the version index.

[0043] Furthermore, the device also includes:

[0044] A new version number generation module is used to record the modified content and generate a new version number when a file is modified;

[0045] A modification module, used to modify the object index according to the modification content;

[0046] The level index modification module is used to modify the level index according to the object index.

[0047] Furthermore, the device also includes:

[0048] The level index modification module is used to modify the level index according to the changed level when the level changes;

[0049] A detection module, used to detect whether the object has changed according to the changed level, and modify the object index when the object has changed;

[0050] The associated index modification module is used to modify the associated index between the level index and the object index.

[0051] Based on the above embodiments, the device further includes:

[0052] The level index modification module is used to modify the level index according to the changed level when the level changes;

[0053] A detection module, used to detect whether the object has changed according to the changed level, and modify the object index when the object has changed;

[0054] The associated index modification module is used to modify the associated index between the level index and the object index.

[0055] Furthermore, the level index modification module includes:

[0056] The first level index modification unit is used to detect the object classification change if the high level is changed to the low level, and modify the level index according to the object classification change.

[0057] Furthermore, the level index modification module includes:

[0058] The second level index modification unit is used to detect the change in the number of objects corresponding to the changed level and modify the object index if the low level is changed to the high level.

[0059] Furthermore, the preset division principles include:

[0060] The number of levels in the object is no more than three and the granularity of the smallest level sub-object is no less than the minimum granularity threshold.

[0061] Compared with the prior art, the multi-version file management method and device for surveying and mapping projects of the present invention have the following advantages: the multi-version file management method and device for surveying and mapping projects of the present invention divide the surveying and mapping file into multiple sub-files according to the hierarchical affiliation principle; classify the sub-files according to the expected update frequency and set the corresponding level; determine the number of objects in the next level in the sub-file according to the level so that the number of objects matches the level; classify the objects in the next level according to the expected update frequency and design the corresponding object level; determine the number of sub-objects in the next level object according to the level so that the number of sub-objects matches the object level; return to determine the number of objects in the next level in the sub-file according to the level until the preset division principle is met; establish object indexes for the sub-objects and objects. According to the characteristics of the surveying and mapping file, an index with certain expansion capabilities can be set up in advance to facilitate the modification of the surveying and mapping file later. And modify the version and index. Only the part modified each time can be incrementally stored, and the corresponding version index can be recorded. It effectively reduces the data expansion caused by each version change, and through the changes in multi-level indexes, the corresponding modified content can be quickly found, which is particularly suitable for distributed database storage. Compared with the existing technology, it can effectively reduce storage costs and ensure the consistency of each version of data. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0063] Figure 1 A flowchart of a multi-version file management method applicable to a surveying and mapping project according to an embodiment of the present invention;

[0064] Figure 2 It is a schematic diagram of the structure of a multi-version file management device suitable for surveying and mapping projects according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0066] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0067] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0068] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0069] Embodiment 1

[0070] Figure 1 The multi-version file management method applicable to surveying and mapping projects described in Example 1 of the present invention is suitable for managing multi-version surveying and mapping files generated by surveying and mapping projects. The method can be implemented by a multi-version file management device applicable to surveying and mapping projects. The multi-version file management device applicable to surveying and mapping projects can be implemented by software and / or hardware, and can be integrated into a distributed database management system (DDBMS).

[0071] See also Figure 1 The multi-version file management method applicable to surveying and mapping projects includes:

[0072] S110, dividing the surveying and mapping file into multiple sub-files according to the hierarchical affiliation principle.

[0073] At present, urban testing usually includes urban control measurement, urban topographic mapping, compilation of various thematic maps, construction layout during the construction of municipal engineering, and deformation observation of important buildings. Its data information is usually stored as a complete shapefile file, in which the spatial relationship of buildings and building attributes are stored. In this embodiment, it can be divided into multiple subfiles according to the hierarchical district principle to facilitate the management of the mapping file. Exemplary, taking the building information collection project of T city as an example, the data information is stored as a complete shapefile file, and the spatial relationship of buildings and building attributes need to be saved. T city has five districts, A, B, C, D, and E. And the shapefile file can be divided into five major parts, a, b, c, d, and e, according to the five districts of A, B, C, D, and E. The above-mentioned hierarchical district principle is used for division, mainly considering the following factors: the operation process needs to be carried out one district at a time, and according to the project plan, the building information is collected in the order of A, B, C, D, and E. And the planning of each district is also different. Therefore, the adoption of the hierarchical zoning principle can effectively reduce the number of upgrades and modifications to surveying and mapping files, and reduce the amount of stored data and versions.

[0074] S120, classifying the sub-files according to the expected update frequency and setting corresponding levels.

[0075] Surveying and mapping projects have their own geographical particularities, and the update of data files is generally continuously updated with data within a certain geographical range. In this embodiment, the geographical range can be a certain administrative area. Due to different planning and development status of different administrative regions, the possibility of updating their buildings is also different. For example: in a newly built development zone, since it is in the initial stage of development, the roads and buildings may be updated in a relatively short period of time, while for the built old urban area, due to its mature development, the possibility of large-scale changes in buildings is low, and the possibility of updating is low.

[0076] For areas with a higher possibility of update, the frequency of building update is also faster, so the data in the area will continue to be updated. In this embodiment, the above sub-files can be graded according to the expected update frequency and the corresponding levels can be set. For example, the levels of a, b, c, d, and e can be 10, 5, 0, 0, and 0 respectively. The levels of a and b are higher than those of c, d, and e, so their update frequency may be higher.

[0077] S130: Determine the number of objects in the next layer in the subfile according to the level, so that the number of objects matches the level.

[0078] At the same time, the content of part a is used to determine the level of level a according to the level, and to determine the number of streets and towns at the next level. If the level is high, there will be an object corresponding to each street and town. If the level is low, it is possible that multiple streets and towns share one object.

[0079] S140, classifying the next-level objects according to the expected update frequency and setting the corresponding object levels.

[0080] For example, the street-level objects can be graded to the next level to form the next level objects, and the above method can be used to grade them and set the corresponding levels.

[0081] S150: Determine the number of sub-objects in the next-level object according to the level, so that the number of sub-objects more or less matches the object level.

[0082] In this embodiment, the lower layer of the object is divided into sub-objects, and the number of sub-objects is determined according to the object level.

[0083] S160, returning to determine the number of next-level objects in the sub-file according to the level until a preset division principle is met.

[0084] Repeat the above steps to divide the surveying and mapping files into multi-level files, and fully consider the changes in surveying and mapping data in the future during the splitting process. Leave room for the expansion of surveying and mapping data. In this embodiment, the preset rules may include: the number of levels in the object is no more than three layers and\or the granularity of the smallest level sub-object is not less than the minimum granularity threshold. By limiting the number of levels, it is possible to avoid meaningless further subdivision of objects and meet the minimum level of regional planning and the corresponding surveying and mapping workload. Granularity refers to the level of refinement or integration of data stored in the data unit of the data warehouse. The higher the degree of refinement, the smaller the granularity level; conversely, the lower the degree of refinement, the larger the granularity level. The same limitation on the minimum granularity avoids excessive differential splitting of objects.

[0085] S170: Create object indexes for the sub-objects and objects.

[0086] An index is a separate, physical storage structure that sorts the values ​​of one or more columns in a database table. It is a collection of values ​​of one or more columns in a table and a corresponding list of logical pointers to the data pages that physically identify these values ​​in the table. The role of an index is equivalent to the catalog of a book, and you can quickly find the required content based on the page numbers in the catalog.

[0087] An index provides pointers to the data values ​​stored in a specified column of a table, and then sorts these pointers according to the sort order you specify. The database uses the index to find a specific value, and then follows the pointer to find the row containing the value. This allows the SQL statement corresponding to the table to execute faster and quickly access specific information in the database table. In this embodiment, the use of the index can not only quickly find the corresponding data, but also serve as a record of changes in the version of the surveying and mapping file.

[0088] Therefore, in this embodiment, after the hierarchical division, indexes are created for the sub-objects and objects to record the corresponding mapping file contents, so as to facilitate the search for storage addresses.

[0089] Optionally, the method may further include: creating a level index, and creating an associated index between the level index and the object index; and using the level index, object index and associated index as a version index. Since grading is an important element in building documents, a level index is established for grading, and an associated index is created between the level index and the object index. This facilitates quick search of content by level or object. And the associated index can be used to determine whether a level or object has changed. The level index, object index and associated index are used as a version index. This facilitates determining whether a modification has been made and the modified content from the version index. This prevents confusion among multiple versions.

[0090] The embodiment of the present invention divides the surveying and mapping file into multiple sub-files according to the hierarchical region principle; the sub-files are graded according to the expected update frequency and the corresponding levels are set; the number of objects in the next level in the sub-file is determined according to the level so that the number of objects matches the level; the objects in the next level are graded according to the expected update frequency and the corresponding object level is designed; the number of sub-objects in the next level object is determined according to the level so that the number of sub-objects matches the object level; the number of objects in the next level in the sub-file is determined according to the level until the preset division principle is met; and object indexes are established for the sub-objects and objects. According to the characteristics of the surveying and mapping file, an index with certain expansion capability can be pre-established to facilitate the modification of the surveying and mapping file in the later stage. And the version and index are modified. Only the part modified each time can be incrementally stored, and the corresponding version index can be recorded. The data expansion caused by each version change is effectively reduced, and the corresponding modified content can be quickly found through the change of the multi-level index, which is particularly suitable for distributed database storage. Compared with the prior art, the storage cost can be effectively reduced, and the consistency of each version data can be guaranteed.

[0091] In a preferred implementation of this embodiment, the method may further add the following steps: when a file is modified, record the modified content and generate a new version number; modify the object index according to the modified content; modify the level index according to the object index. Generate a new version number by using the file modification, determine the object where the modified content is located according to the modified content, modify the object index, and determine whether the object level has changed. When the object level has changed, modify the level index together.

[0092] In another preferred implementation of this embodiment, the method may further add the following steps: when the level changes, modify the level index according to the changed level; detect whether the object changes according to the changed level, and modify the object index when the object changes; modify the associated index between the level index and the object index. Specifically, when the level changes, modify the level index according to the changed level, including: if the high level changes to the low level, detect the object classification change, and modify the level index according to the object classification change. Or if the low level changes to the high level, detect the corresponding number change corresponding to the changed level, and modify the object index. When the level changes, usually the number of the corresponding objects or sub-objects will also change accordingly, which will lead to index errors. Therefore, in this embodiment, once the level changes, it is necessary to examine whether the corresponding object has changed.

[0093] When the high level is changed to the low level, it is detected whether the corresponding object has changed in level. In one case, it may be that the level of the sub-objects included in it has changed, which in turn causes its level to change. Therefore, it is necessary to detect the change in the level of the object, and then modify the level index according to the change in the object level. Correspondingly, when the low level is changed to the high level, the number of objects will inevitably change, and the index should be modified according to the change in the object. In addition, for a distributed database, once the level of an object changes, it is equivalent to a change in its importance, and the reversibility of the importance is low. And it is stored as one of the historical versions for later tracing. Therefore, its redundant backup degree should also be processed accordingly to reduce the amount of data storage. Exemplarily, when its level is less than the preset level threshold, the number of copies can be reduced to half the number of nodes in the distributed database minus one, which can reduce the storage amount while ensuring data security, and accordingly, establish a corresponding version index. Stored in the DDBMS. Correspondingly, when the low level is changed to the high level, when the number of objects changes, the object index is modified. Optionally, the number of corresponding copies in the distributed database can be adjusted according to whether the number of object changes, especially the number of objects increased, exceeds the preset object data addition threshold. Optionally, the number of replicas can be increased to half the number of nodes in the distributed database plus one, and as the number of objects changes multiple times, it can be determined whether it exceeds one of multiple preset object data addition thresholds, and the number of replicas can be adjusted accordingly to meet data security requirements.

[0094] Embodiment 2

[0095] Figure 2 is a schematic diagram of the structure of a multi-version file management device applicable to surveying and mapping projects according to the second embodiment of the present invention, see Figure 2 , the multi-version file management device suitable for surveying and mapping projects comprises:

[0096] A division module 210 is used to divide the surveying and mapping file into a plurality of sub-files according to the hierarchical region principle;

[0097] A setting module 220, used for classifying the sub-files according to the expected update frequency and setting corresponding levels;

[0098] A determination module 230, configured to determine the number of objects in the next level in the subfile according to the level, so that the number of objects matches the level;

[0099] A grading module 240, configured to grade the next-level objects according to the expected update frequency and set the corresponding object level;

[0100] A quantity determination module 250, for determining the number of sub-objects in the next-level object according to the level, so that the number of sub-objects more or less matches the level of the object;

[0101] A return module 260 is used to return the number of objects in the next level of the sub-file determined according to the level until a preset division principle is met;

[0102] The establishing module 270 is used to establish object indexes for the sub-objects and objects.

[0103] The multi-version file management device for surveying and mapping projects provided by the embodiment of the present invention divides the surveying and mapping file into multiple sub-files according to the hierarchical affiliation principle; grades the sub-files according to the expected update frequency and sets the corresponding level; determines the number of objects in the next level in the sub-file according to the level so that the number of objects matches the level; grades the objects in the next level according to the expected update frequency and designs the corresponding object level; determines the number of sub-objects in the next level object according to the level so that the number of sub-objects matches the object level; returns to determine the number of objects in the next level in the sub-file according to the level until the preset division principle is met; and establishes an object index for the sub-objects and objects. According to the characteristics of the surveying and mapping file, an index with certain expansion capability can be pre-established to facilitate the modification of the surveying and mapping file later. And the version and index can be modified. Only the part modified each time can be incrementally stored, and the corresponding version index can be recorded. The data expansion caused by each version change is effectively reduced, and the corresponding modified content can be quickly found through the change of the multi-level index, which is particularly suitable for distributed database storage. Compared with the existing technology, it can effectively reduce storage costs and ensure the consistency of data in each version.

[0104] Based on the above embodiments, the device further includes:

[0105] An index creation module, used to create a level index and create an associated index between the level index and the object index;

[0106] The version index generating module is used to use the level index, object index and association index as the version index.

[0107] Based on the above embodiments, the device further includes:

[0108] A new version number generation module is used to record the modified content and generate a new version number when a file is modified;

[0109] A modification module, used to modify the object index according to the modification content;

[0110] The level index modification module is used to modify the level index according to the object index.

[0111] Based on the above embodiments, the device further includes:

[0112] The level index modification module is used to modify the level index according to the changed level when the level changes;

[0113] A detection module, used to detect whether the object has changed according to the changed level, and modify the object index when the object has changed;

[0114] The associated index modification module is used to modify the associated index between the level index and the object index.

[0115] Based on the above embodiments, the level index modification module includes:

[0116] The first level index modification unit is used to detect the object classification change if the high level is changed to the low level, and modify the level index according to the object classification change.

[0117] Based on the above embodiments, the level index modification module includes:

[0118] The second level index modification unit is used to detect the change in the number of objects corresponding to the changed level and modify the object index if the low level is changed to the high level.

[0119] Based on the above embodiments, the preset division principles include:

[0120] The number of levels in the object is no more than three and the granularity of the smallest level sub-object is no less than the minimum granularity threshold.

[0121] The multi-version file management device applicable to surveying and mapping projects provided by the embodiment of the present invention can execute the multi-version file management method applicable to surveying and mapping projects provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-version file management method suitable for surveying and mapping projects, characterized in that: include: Dividing the surveying and mapping file into multiple sub-files according to the hierarchical principle; Classifying the sub-files according to the expected update frequency and setting corresponding levels; Determine the number of objects in the next level in the subfile according to the level, so that the number of objects matches the level; Classifying the next-level objects according to the expected update frequency and setting corresponding object levels; Determining the number of sub-objects in the next-level object according to the level so that the number of sub-objects more or less matches the level of the object; Returning the number of objects of the next level in the sub-file determined according to the level until a preset division principle is met, wherein the preset division rule includes: the number of levels in the object is not more than three and / or the granularity of the smallest level sub-object is not less than a minimum granularity threshold; An object index is created for the sub-object and the object.

2. The method according to claim 1, characterized in that The method further comprises: Create a level index and create an associated index between the level index and the object index; The level index, object index and association index are used as version indexes.

3. The method according to claim 1, characterized in that , the method further comprises: When a file is modified, the modified content is recorded and a new version number is generated; Modify the object index according to the modified content; The level index is modified according to the object index.

4. The method according to claim 1, characterized in that The method further comprises: When the level changes, the level index is modified according to the changed level; Detect whether the object has changed according to the changed level, and modify the object index when the object has changed; Modify the associated index between the level index and the object index.

5. The method according to claim 4, characterized in that When the level changes, modifying the level index according to the changed level includes: If the high level is changed to a low level, an object classification change is detected, and the level index is modified according to the object classification change.

6. The method according to claim 4, characterized in that When the level changes, modifying the level index according to the changed level includes: If the low level is changed to a high level, the change in the number of objects corresponding to the changed level is detected and the object index is modified.

7. A multi-version file management device suitable for surveying and mapping projects, characterized in that: include: A division module, used for dividing the surveying and mapping file into a plurality of sub-files according to the hierarchical affiliation principle; A setting module, used for grading the sub-files according to the expected update frequency and setting the corresponding levels; A determination module, configured to determine the number of objects in the next level in the subfile according to the level, so that the number of objects matches the level; A grading module, used for grading the objects at the next level according to the expected update frequency and setting the corresponding object level; A quantity determination module, used to determine the number of sub-objects in the next-level object according to the level, so that the number of sub-objects more or less matches the level of the object; A return module, used for returning the number of objects of the next level in the sub-file determined according to the level, until a preset division principle is met, wherein the preset division rule includes: the number of levels in the object is not more than three and / or the granularity of the smallest level sub-object is not less than a minimum granularity threshold; A building module is used to build object indexes for the sub-objects and objects.

8. The device according to claim 7, characterized in that The device also includes: An index creation module, used to create a level index and create an associated index between the level index and the object index; The version index generating module is used to use the level index, object index and association index as the version index.

9. The device according to claim 7, characterized in that The device also includes: A new version number generation module is used to record the modified content and generate a new version number when a file is modified; A modification module, used to modify the object index according to the modification content; The level index modification module is used to modify the level index according to the object index.

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