Database system, computer program product, electronic device, and storage medium

Abstract

The present specification provides a database system, a computer program product, an electronic device, and a storage medium, the database system comprising: a logic layer for recording a logic structure of data in the database system, the logic structure comprising a plurality of data partitions; the Tablet object layer comprises a plurality of Tablet objects distributed in a plurality of database instances; the Tablet information layer is used for recording meta information of Tablet objects in the Tablet object layer, and the meta information comprises physical positions of the Tablet objects in the database instances and data partitions corresponding to the Tablet objects; wherein the data in the data partition is stored in the Tablet object corresponding to the logic partition.

Description

Technical Field

[0001] One or more embodiments of the present specification relate to the field of database technology, and in particular, to a database system, a computer program product, an electronic device, and a storage medium. Background Art

[0002] In recent years, with the rapid development of the Internet and informatization, the generation of data has exploded, so the requirements for databases and their management are getting higher and higher. The current distributed database has multiple database instances, which can provide multiple data copies to increase the stability of the distributed database, and the data tables in the distributed database are often divided into partitions for storage to improve the efficiency of data management.

[0003] In the related art, the execution efficiency and effect of relatively simple partition management operations in a distributed database are acceptable, but the execution efficiency and effect of relatively complex partition management operations need to be improved. Summary of the invention

[0004] In view of this, one or more embodiments of the present specification provide a database system, a computer program product, an electronic device, and a storage medium.

[0005] To achieve the above objectives, one or more embodiments of this specification provide the following technical solutions:

[0006] According to a first aspect of one or more embodiments of this specification, a database system is provided, the system comprising:

[0007] The logic layer is used to record the logical structure of data in the database system, wherein the logical structure includes multiple data partitions;

[0008] Tablet object layer, including multiple Tablet objects distributed in multiple database instances;

[0009] Tablet information layer, used to record the meta information of Tablet objects in the Tablet object layer, the meta information including the physical location of the Tablet objects in the multiple database instances, and the data partition corresponding to the Tablet objects;

[0010] The data in the data partition is stored in the Tablet object corresponding to the logical partition.

[0011] In one or more possible embodiments of the present specification, when the database system performs a DDL operation on the logical structure, it updates the metadata of the Tablet object corresponding to the data partition involved in the DDL operation, and / or performs the operation on the Tablet object corresponding to the data partition involved in the DDL operation within the Tablet object layer.

[0012] In one or more possible embodiments of the present specification, when the database system performs partition exchange on any two data partitions in the logical structure, the Tablet objects corresponding to any two data partitions are exchanged in the Tablet information layer.

[0013] In one or more possible embodiments of the present specification, when the database system executes Truncate on any data partition in the logical structure, the metadata of the Tablet object corresponding to any data partition is retained in the Tablet information layer, and the data in the Tablet object corresponding to any data partition is deleted in the Tablet object layer.

[0014] In one or more possible embodiments of the present specification, when the database system performs partition splitting on any data partition in the logical structure, the Tablet object corresponding to any data partition is split into two Tablet objects in the Tablet object layer, and metadata is added to the two Tablet objects obtained by the split in the Tablet information layer.

[0015] In one or more possible embodiments of the present specification, when the database system performs a partition merge on any two data partitions in the logical structure, the Tablet objects corresponding to the any two data partitions are merged into one Tablet object in the Tablet object layer, and metadata is added to the merged Tablet object in the Tablet information layer.

[0016] In one or more possible embodiments of the present specification, when the database system backs up any data partition in the logical structure, it copies the data in the Tablet object corresponding to any data partition to a blank Tablet object in the Tablet object layer, and adds metadata to the blank Tablet object in the Tablet information layer.

[0017] In one or more possible embodiments of the present specification, when the database system migrates any data partition in the logical structure, the tablet object corresponding to any data partition is migrated in the tablet object layer, and the metadata of the migrated tablet object is updated in the tablet information layer.

[0018] In one or more possible embodiments of the present specification, when the database system has multiple DDL operations respectively for multiple data partitions within the logical structure, the multiple DDL operations are performed in parallel on the Tablet objects corresponding to the multiple logical partitions.

[0019] In one or more possible embodiments of the present specification, the database system synchronously updates the metadata of related Tablet objects in the Tablet information layer when changes occur to Tablet objects in the Tablet object layer.

[0020] In one or more possible embodiments of the present specification, when any Tablet object in the Tablet object layer is migrated from one database instance to another database instance, the database system modifies the physical location of any Tablet object in the multiple database instances in the Tablet information layer.

[0021] In one or more possible embodiments of the present specification, when the database system adds at least one Tablet object in the Tablet object layer, it adds metadata for the at least one added Tablet object in the Tablet information layer.

[0022] In one or more possible embodiments of the present specification, the Tablet object corresponding to the local index table within the logical layer and the Tablet object corresponding to the main table of the local index table are in the same database instance.

[0023] According to a second aspect of one or more embodiments of this specification, a computer program product is provided, comprising a computer program / instruction, which implements the database system described in the first aspect when executed by a processor.

[0024] According to a third aspect of one or more embodiments of this specification, an electronic device is provided, including:

[0025] processor;

[0026] a memory for storing processor-executable instructions;

[0027] The processor implements the database system as described in the first aspect by running the executable instructions.

[0028] According to a fourth aspect of one or more embodiments of the present specification, a computer-readable storage medium is provided, on which computer instructions are stored. When the instructions are executed by a processor, the database system described in the first aspect is implemented.

[0029] The technical solutions provided by the embodiments of this specification may have the following beneficial effects:

[0030] The database system provided in the embodiments of this specification includes a logical layer targeted by user instructions, a Tablet object layer undertaken by multiple database instances in a distributed database, and a Tablet information layer between the logical layer and the Tablet object layer. The Tablet information layer can record the physical location of each Tablet object in the multiple database instances, as well as the data partitions corresponding to each Tablet object, so that the Tablet object layer can exist independently of the logical layer relative to the traditional storage layer, that is, the storage layer and the logical layer are decoupled. This decoupling makes storage management more flexible, thereby making partition management operations flexible, convenient and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of a distributed database based on an LSM-Tree storage engine provided by an exemplary embodiment.

[0032] Figure 2 It is an architectural diagram of a database system provided by an exemplary embodiment.

[0033] Figure 3 It is an architectural diagram of a database system in related technology.

[0034] Figure 4 It is a schematic diagram of partition exchange in a database system provided by an exemplary embodiment.

[0035] Figure 5 It is a structural schematic diagram of a device provided by an exemplary embodiment. DETAILED DESCRIPTION

[0036] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with one or more embodiments of this specification. Instead, they are merely examples of devices and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0037] It should be noted that: in other embodiments, the steps of the corresponding method are not necessarily performed in the order shown and described in this specification. In some other embodiments, the steps included in the method may be more or less than those described in this specification. In addition, a single step described in this specification may be decomposed into multiple steps for description in other embodiments; and multiple steps described in this specification may be combined into a single step for description in other embodiments.

[0038] First, some concepts involved in this specification are explained.

[0039] Storage: refers to the way and structure of physical storage of data.

[0040] Schema: refers to the logical structure of the database, including tables, columns, data types, indexes, constraints and other database metadata.

[0041] Partition: Referring to the concept of traditional database partition tables, the data of a table can be horizontally split into multiple shards according to certain rules. Each shard is called a table partition, or partition for short.

[0042] Tablet: The basic unit of data sharding, representing the physical storage unit of data blocks actually stored on disk. Each tablet can contain one or more partitions of one or more user tables.

[0043] Based on the above technical problems mentioned in the background technology, at least one embodiment of this specification provides a database system, which can be applied to the following Figure 1 The distributed database based on the LSM-Tree storage engine, or other types of databases are shown.

[0044] Please refer to the attached Figure 2 , which exemplarily shows the architecture of the database system.

[0045] The database system includes a logic layer, a tablet information layer and a tablet object layer.

[0046] The logic layer is used to record the logical structure of data in the database system, including multiple data partitions. The logical structure is the Schema, which includes database metadata such as tables, partitions, columns, data types, indexes, constraints, etc. For example, the logic layer records multiple tables in the database system, as well as information such as partitions, rows, columns, data types, indexes, etc. of each table.

[0047] The Tablet object layer includes multiple Tablet objects distributed in multiple database instances. From the above introduction, it can be seen that the Tablet object represents the data block actually stored on the disk, corresponding to a physical storage unit; the Tablet object does not contain any logical layer information, is a logical container for data storage, provides data reading and writing services, and the Tablet object can be migrated between different database instances (the physical address corresponding to the Tablet object will change after migration); if the Tablet in the Tablet object layer is not enough to store the data in the database, and there is idle storage space in multiple database instances, Tablet objects can be further added and storage space can be allocated for them.

[0048] The Tablet information layer is located between the logical layer and the Tablet object layer, and is used to record the meta information of the Tablet objects in the Tablet object layer, and the meta information includes the physical location of the Tablet objects in the multiple database instances, and the data partitions corresponding to the Tablet objects. For example, the meta information may also include the data range of the data partition corresponding to the Tablet object, such as recording the data range by primary key, or recording the data range by data volume, etc. The data in the data partition is stored in the Tablet object corresponding to the logical partition.

[0049] Preferably, the Tablet object corresponding to the local index table in the logic layer and the Tablet object corresponding to the main table of the local index table are in the same database instance. This can improve data processing efficiency and reduce query operation delays.

[0050] Relative to Figure 3In the related technology shown, the data partition in the logical layer is tightly coupled with the partition object in the storage layer. In this database system, the storage layer is abstracted by introducing the Tablet object, which enhances the flexibility and maintainability of the database. The Tablet object is used to represent the actual data storage object, aiming to establish a mapping from data partitions (such as user table partitions) to Tablet objects, and realize the decoupling between data storage and schema metadata of the logical layer. First, the logical partition of the user table is mapped to one or more Tablet objects. This mapping mechanism ensures the separation of data organization in the logical layer from Tablet objects at the physical storage level. Therefore, when operating the physical storage of data, it is not necessary to directly operate the partition of the user table, but it can be achieved by operating the Tablet object, so that the performance can be optimized more effectively for the specific storage layer, for example, to achieve more sophisticated resource management and data access strategies. Secondly, the decoupling of data storage and Schema metadata gives the database system greater flexibility in data storage structure. Therefore, when users perform operations such as partition exchange and Truncate, it will not affect the upper-layer Schema metadata.

[0051] Based on the above characteristics of the database system, in some embodiments of the present disclosure, when performing a DDL (Data Definition Language) operation on the logical structure, the database system can update the metadata of the Tablet object corresponding to the data partition involved in the DDL operation, and / or perform operations on the Tablet object corresponding to the data partition involved in the DDL operation in the Tablet object layer. That is, when performing a DDL operation on a logical partition in a user table, the operation can be performed in the Tablet object layer and the Tablet information layer respectively, or in one of the layers, instead of applying the DDL operation as a whole to the storage layer, thereby simplifying the operation and improving efficiency.

[0052] The following examples will be used to describe in detail the specific methods for executing DDL operations on the database system.

[0053] Example 1

[0054] When performing partition exchange on any two data partitions in the logical structure, the database system can exchange the tablet objects corresponding to the two data partitions in the tablet information layer, without performing actual operations on the data at the storage level, and only updating the meta-information in the tablet information layer.

[0055] Please refer to the attached Figure 4, which takes the P0 partition exchange of the T1 table and the T2 table as an example to illustrate the partition exchange method of the example. Tablet 1 and Tablet 2 represent two independent storage units, each carrying a set of data; before the partition exchange, the T1 table corresponds to Tablet 1, and the P0 partition of the T2 table corresponds to Tablet 2. By exchanging Tablet 1 corresponding to the T1 table with Tablet 2 corresponding to the P0 partition of the T2 table, so that the T1 table corresponds to Tablet 2, and the P0 partition of the T2 table corresponds to Tablet 1, the partition exchange of the P0 partition of the T1 table and the T2 table is completed.

[0056] Example 2

[0057] When the database system performs a Truncate (clear operation) on any data partition in the logical structure, the metadata of the Tablet object corresponding to any data partition is retained in the Tablet information layer, and the data in the Tablet object corresponding to any data partition is deleted in the Tablet object layer. The data in the Tablet object can be operated directly without involving and affecting the logical structure of the logical layer (such as the table structure, etc.).

[0058] Example 3

[0059] When the database system performs partition splitting on any data partition in the logical structure, the tablet object corresponding to the data partition is split into two tablet objects in the tablet object layer, and metadata is added to the two tablet objects obtained by splitting in the tablet information layer. At the same time, the metadata of the tablet object before the splitting needs to be deleted.

[0060] Example 4

[0061] When the database system performs partition merging on any two data partitions in the logical structure, the tablet objects corresponding to the two data partitions are merged into one tablet object in the tablet object layer, and metadata is added to the merged tablet object in the tablet information layer. At the same time, the metadata of the two tablet objects before the merge needs to be deleted.

[0062] From the execution methods of partition splitting and partition merging in the above examples 3 and 4, it can be seen that the database system can make partition splitting and partition merging operations simpler at the physical level and can be completed without making complex changes to the user table structure.

[0063] Example 5

[0064] When the database system backs up any data partition in the logical structure, it copies the data in the Tablet object corresponding to any data partition to a blank Tablet object in the Tablet object layer, and adds metadata to the blank Tablet object in the Tablet information layer.

[0065] Example 6

[0066] When the database system migrates any data partition in the logical structure, it migrates the Tablet object corresponding to any data partition in the Tablet object layer, and updates the metadata of the migrated Tablet object in the Tablet information layer.

[0067] From the execution methods of partition backup and partition migration in Examples 5 and 6 above, it can be seen that the database system simplifies database maintenance. For common management tasks such as backup, recovery, migration, etc., it can be operated more flexibly and efficiently because these operations are now performed on physical storage units. Therefore, the database system has high availability and strong disaster recovery capabilities. Managing replicas at the Tablet level can simplify disaster recovery and replica management. When it is necessary to restore data in a specific partition, the Tablet object can be rebuilt or migrated faster without involving the reconstruction of the entire database.

[0068] It should also be understood that when the database system has multiple DDL operations for multiple data partitions in the logical structure, the multiple DDL operations can be performed in parallel on the Tablet objects corresponding to the multiple logical partitions, because these operations are for multiple Tablet objects, rather than the entire data table or the entire physical storage layer.

[0069] Based on the above characteristics of the database system, in some embodiments of the present disclosure, the database system synchronously updates the metadata of the related Tablet objects in the Tablet information layer when the Tablet objects in the Tablet object layer change. In other words, when multiple database instances are load balanced based on consensus protocols such as the Paxos protocol, the Tablet objects in the Tablet object layer can be transferred, and this transfer does not affect the logical structure of the data table in the logical layer. Only the metadata in the Tablet information layer needs to be updated. This enables the database instance to manage the resources at the physical storage level more timely, effectively, and efficiently, and improves the data processing capability and efficiency of the entire database system.

[0070] For example, when any Tablet object in the Tablet object layer is migrated from one database instance to another database instance, the database system modifies the physical location of any Tablet object in the multiple database instances in the Tablet information layer.

[0071] For another example, when the database system adds at least one Tablet object in the Tablet object layer, it adds metadata for the at least one added Tablet object in the Tablet information layer.

[0072] In summary, the concept of Tablet objects in the Tablet object layer decouples storage objects and schemas, making the management of stored data simpler and supporting richer and more advanced data management operations, including partition exchange, truncate, split, merge, parallel DDL, tenant snapshots, etc., improving the scalability, performance, and management convenience of distributed database systems, while providing a framework for future function and feature expansion. These advantages are crucial to meeting the database requirements of modern large-scale online services.

[0073] Therefore, the database system has the convenience of stand-alone deployment as well as the scalability and high availability of a distributed system. It is suitable for both small and medium-sized business scenarios that do not require particularly high performance, and large enterprise-level applications that require large-scale distributed deployment.

[0074] Integration of stand-alone mode and distributed architecture: The database system supports deployment in stand-alone mode, which is very useful for small-scale deployment and low performance requirements. At the same time, it also supports seamless transition to distributed mode, providing data expansion and distributed computing capabilities across multiple server nodes. This integrated design allows users to flexibly expand according to business needs. As the amount of data grows and the complexity of business increases, the database system can help enterprises smoothly transition to a distributed architecture without having to replace the database system, thereby protecting the company's technology investment.

[0075] High availability: Using distributed architecture and multi-copy mechanism, the database system can ensure high availability. It uses consensus protocols such as Paxos protocol to ensure data consistency, and handles failures through automatic failover and recovery mechanism to maintain continuous operation of the business.

[0076] Scalability: The database system supports horizontal expansion and can handle larger data volumes and higher concurrent requests by adding more server nodes. This scalability applies not only to storage capacity but also to computing power, allowing the system to automatically adjust resource allocation based on load.

[0077] The database system provided in the embodiments of this specification includes a logical layer targeted by user instructions, a Tablet object layer undertaken by multiple database instances in a distributed database, and a Tablet information layer between the logical layer and the Tablet object layer. The Tablet information layer can record the physical location of each Tablet object in the multiple database instances, as well as the data partitions corresponding to each Tablet object, so that the Tablet object layer can exist independently of the logical layer relative to the traditional storage layer, that is, the storage layer and the logical layer are decoupled. This decoupling makes storage management more flexible, thereby making partition management operations flexible, convenient and efficient.

[0078] Simplified data management: After decoupling, data management becomes simpler. Database administrators can operate the underlying data more directly without worrying about damaging the upper-level schema. This simplification can speed up database maintenance and data operations and reduce the risk of errors.

[0079] Support for advanced data operations: Due to the independence of the storage layer, the database system can more easily support advanced data management operations, such as partition exchange, truncate, split, merge, parallel DDL operations, and tenant snapshots. These operations are crucial for large-scale data processing and maintenance, and can enhance the database's ability to handle complex tasks.

[0080] Partition management optimization: Through Tablet objects, the database system can perform partition-related operations more efficiently, such as dynamic partition splitting and merging, to adapt to changes in data capacity and fluctuations in query load.

[0081] According to a second aspect of one or more embodiments of this specification, a computer program product is provided, comprising a computer program / instruction, which implements the database system described in the first aspect when executed by a processor.

[0082] According to a third aspect of one or more embodiments of this specification, an electronic device is provided, including:

[0083] processor;

[0084] a memory for storing processor-executable instructions;

[0085] The processor implements the database system as described in the first aspect by running the executable instructions.

[0086] Figure 5is a schematic structural diagram of the electronic device provided by an exemplary embodiment. Figure 5 At the hardware level, the device includes a processor 502, an internal bus 504, a network interface 506, a memory 508, and a non-volatile memory 510, and may also include hardware required for other tasks. One or more embodiments of this specification may be implemented based on software, such as the processor 502 reading the corresponding computer program from the non-volatile memory 510 into the memory 508 and then running it. Of course, in addition to the software implementation, one or more embodiments of this specification do not exclude other implementations, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0087] According to a fourth aspect of one or more embodiments of the present specification, a computer-readable storage medium is provided, on which computer instructions are stored. When the instructions are executed by a processor, the database system described in the first aspect is implemented.

[0088] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer, which may be in the form of a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email transceiver, a game console, a tablet computer, a wearable device or a combination of any of these devices.

[0089] In a typical configuration, a computer includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0090] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0091] Computer-readable media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. Information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, disk storage, quantum memory, graphene-based storage media or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0092] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0093] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0094] The terms used in one or more embodiments of this specification are only for the purpose of describing specific embodiments, and are not intended to limit one or more embodiments of this specification. The singular forms of "a", "said" and "the" used in one or more embodiments of this specification and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0095] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this manual are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0096] It should be understood that although the terms first, second, third, etc. may be used to describe various information in one or more embodiments of this specification, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of one or more embodiments of this specification, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0097] The above description is merely a preferred embodiment of one or more embodiments of the present specification and is not intended to limit one or more embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present specification shall be included in the scope of protection of one or more embodiments of the present specification.

Claims

1. A database system, comprising: The logic layer is used to record the logical structure of data in the database system, and the logical structure includes multiple data partitions; Tablet object layer, including multiple Tablet objects distributed in multiple database instances; Tablet information layer, used to record the meta information of Tablet objects in the Tablet object layer, the meta information including the physical location of the Tablet objects in the multiple database instances, and the data partition corresponding to the Tablet objects; The data in the data partition is stored in the Tablet object corresponding to the logical partition.

2. According to the database system according to claim 1, when the database system performs a DDL operation on the logical structure, it updates the metadata of the Tablet object corresponding to the data partition involved in the DDL operation, and / or performs operations on the Tablet object corresponding to the data partition involved in the DDL operation within the Tablet object layer.

3. According to the database system of claim 2, when the database system performs partition exchange on any two data partitions in the logical structure, the Tablet objects corresponding to any two data partitions are exchanged in the Tablet information layer.

4. According to the database system of claim 2, when the database system executes Truncate on any data partition in the logical structure, the metadata of the Tablet object corresponding to any data partition is retained in the Tablet information layer, and the data in the Tablet object corresponding to any data partition is deleted in the Tablet object layer.

5. According to the database system of claim 2, when the database system performs partition splitting on any data partition in the logical structure, the Tablet object corresponding to any data partition is split into two Tablet objects in the Tablet object layer, and metadata is added to the two Tablet objects obtained by the split in the Tablet information layer.

6. According to the database system of claim 2, when the database system performs partition merging on any two data partitions in the logical structure, the Tablet objects corresponding to the any two data partitions are merged into one Tablet object in the Tablet object layer, and metadata is added to the merged Tablet object in the Tablet information layer.

7. According to the database system of claim 2, when the database system backs up any data partition in the logical structure, the data in the Tablet object corresponding to any data partition is copied to a blank Tablet object in the Tablet object layer, and metadata is added to the blank Tablet object in the Tablet information layer.

8. According to the database system of claim 2, when migrating any data partition in the logical structure, the database system migrates the Tablet object corresponding to any data partition in the Tablet object layer, and updates the metadata of the migrated Tablet object in the Tablet information layer.

9. According to any one of claims 2 to 8, when the database system has multiple DDL operations respectively for multiple data partitions in the logical structure, the multiple DDL operations are performed in parallel on the Tablet objects corresponding to the multiple logical partitions.

10. According to the database system of claim 1, the database system synchronously updates the metadata of the related Tablet objects in the Tablet information layer when the Tablet objects in the Tablet object layer change.

11. According to the database system of claim 10, when any Tablet object in the Tablet object layer is migrated from one database instance to another database instance, the database system modifies the physical location of any Tablet object in the multiple database instances in the Tablet information layer.

12. According to the database system of claim 10, when the database system adds at least one Tablet object in the Tablet object layer, metadata is added to the at least one added Tablet object in the Tablet information layer.

13. According to the database system of claim 1, the Tablet object corresponding to the local index table in the logical layer and the Tablet object corresponding to the main table of the local index table are in the same database instance.

14. A computer program product, comprising a computer program / instruction, which implements the database system according to any one of claims 1 to 13 when executed by a processor.

15. An electronic device, comprising: processor; a memory for storing processor-executable instructions; The processor implements the database system according to any one of claims 1 to 13 by running the executable instructions.

16. A computer-readable storage medium having computer instructions stored thereon, wherein the instructions are executed by a processor to implement the database system according to any one of claims 1 to 13.

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