KR102214696B1 - Optimization techniques for database queries - Google Patents

Abstract

A computer program stored in a computer-readable storage medium according to some embodiments of the present disclosure, wherein the computer program includes instructions for causing a processor of a database server to perform optimization operations for a database query, the operation They are: receiving a query including at least one join operation; Extracting a plurality of expressions used in the same join operation when the query includes an equal join operation; Generating an EQC (Equivalent Class) list including the plurality of expressions; Extracting at least one second filter condition related to the plurality of expressions included in the EQC list from among at least one first filter condition included in the query; Generating a first list including the at least one second filter condition; Generating a third filter condition by analyzing the at least one second filter condition included in the first list by using the EQC list; Generating a second list including the third filter condition; And adding at least one fourth filter condition generated by using the third filter condition to the query.

Description

Optimization techniques for database query {OPTIMIZATION TECHNIQUES FOR DATABASE QUERIES}

The present disclosure relates to a database server and a computer program stored in a computer readable storage medium for performing optimization operations on a database query.

Corporate business is rapidly expanding due to the explosive increase in data and the emergence of various environments and platforms. With the advent of a new business environment, more efficient and flexible data services, information processing, and data management functions are required. In line with these changes, research on databases to solve the problems of high performance, high availability and scalability, which are the basis of corporate business implementation, is continuing.

In a database management system (DBMS), data can be stored in a data store. In a relational database management system (RDBMS), this data store may be referred to as a table. Such a table may include one or more rows, and each of the one or more rows may include one or more columns.

When the database contains a large amount of data, it may take a relatively long time to perform a query for retrieving data of interest to the user. If the database takes a long time to respond to a query, the performance of the database may be adversely affected.

A plurality of execution algorithms (or plans) may be considered in terms of how to process queries issued from clients. Since each execution algorithm has different properties, it is necessary to determine the most suitable algorithm for processing the query before processing the query.

Thus, there may be a need in the art for optimization of queries issued from clients.

US published patent US2015/0347528

The present disclosure has been devised in response to the above-described background technology, and an object of the present disclosure is to provide a database server and a computer program that optimizes a database query.

The technical problems of the present disclosure are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

According to some embodiments of the present disclosure for solving the problems as described above, a computer program stored in a computer-readable storage medium is disclosed. The computer program includes instructions for causing a processor of a database server to perform optimization operations on a database query, the operations including: receiving a query including at least one join operation; Extracting a plurality of expressions used in the same join operation when the query includes an equal join operation; Generating an EQC (Equivalent Class) list including the plurality of expressions; Extracting at least one second filter condition related to the plurality of expressions included in the EQC list from among at least one first filter condition included in the query; Generating a first list including the at least one second filter condition; Generating a third filter condition by analyzing the at least one second filter condition included in the first list by using the EQC list; Generating a second list including the third filter condition; And adding at least one fourth filter condition generated by using the third filter condition to the query.

In addition, the at least one second filter condition has a first sub-filter condition in which a first expression is used among the plurality of expressions and a second sub-filter condition in which a second expression is used among the plurality of expressions, and the EQC The operation of generating a third filter condition by analyzing the at least one second filter condition included in the first list using a list includes comparing the first sub-filter condition and the second sub-filter condition. ; And generating a third filter condition based on a comparison result of the first sub-filter condition and the second sub-filter condition.

In addition, the operation of generating a third filter condition based on the comparison result of the first sub-filter condition and the second sub-filter condition may include, when the first sub-filter condition includes the second sub-filter condition, Generating the third filter condition by changing the second expression of the second sub-filter condition into a blind parameter; And when the second sub-filter condition includes the first sub-filter condition, generating the third filter condition by changing the first expression of the first sub-filter condition to the blind parameter. can do.

In addition, the operation of adding at least one fourth filter condition generated using the third filter condition to the query may include at least one of the plurality of expressions included in the EQC list in the blind parameter of the third filter condition. And generating the at least one fourth filter condition by substituting one expression.

In addition, adding at least one fourth filter condition generated by using the third filter condition to the query includes generating at least one fifth filter condition to be added to the query using the third filter condition Action; Comparing the at least one second filter condition and the at least one fifth filter condition included in the first list; And generating the at least one fourth filter condition based on a result of comparing the at least one second filter condition with the at least one fifth filter condition.

Further, based on a result of comparing the at least one second filter condition and the at least one fifth filter condition, the operation of generating the at least one fourth filter condition may include the at least one second filter condition and Comparing the at least one fifth filter condition to distinguish between the same filter condition and the non-identical filter condition; And recognizing the non-identical filter condition as the at least one fourth filter condition.

Further, the operations may include, when the second filter condition includes the fourth filter condition, deleting the second filter condition from the same join operation in the query; And when the second filter condition does not include the fourth filter condition, maintaining the second filter condition in the same join operation in the query.

In addition, the operation of adding the at least one fourth filter condition to the query includes reflecting the at least one fourth filter condition in the query including the at least one join operation, thereby rewriting the query. Operation; may include.

In addition, each of the first filter condition, the second filter condition, the third filter condition, and the fourth filter condition is a comparison condition of at least one expression and a specific value, a condition that is the same between at least one expression and a specific value, and It may include at least one of at least one expression and a non-equal condition of a specific value.

According to some embodiments of the present disclosure for solving the problems as described above, a database server is disclosed. The database server includes: a communication unit for receiving a query including at least one join operation; And a processor for optimizing the query, wherein the processor extracts a plurality of expressions used for the same join operation when the query includes an equal join operation, and , At least one second filter related to the plurality of expressions included in the EQC list from among at least one first filter condition included in the query, generating an EQC (Equivalent Class) list including the plurality of expressions A condition is extracted, a first list including the at least one second filter condition is generated, and the at least one second filter condition included in the first list is analyzed using the EQC list, and a third A filter condition may be generated, a second list including the third filter condition may be generated, and at least one fourth filter condition generated by using the third filter condition may be added to the query.

In addition, the at least one second filter condition has a first sub-filter condition in which a first expression is used among the plurality of expressions and a second sub-filter condition in which a second expression is used among the plurality of expressions, and the processor When the third filter condition is generated, the first sub-filter condition and the second sub-filter condition are compared, and based on the comparison result of the first sub-filter condition and the second sub-filter condition, a third Filter conditions can be created.

In addition, the processor, when the first sub-filter condition includes the second sub-filter condition, changes the second expression of the second sub-filter condition to a blind parameter to generate the third filter condition, and , When the second sub-filter condition includes the first sub-filter condition, the third filter condition may be generated by changing the first expression of the first sub-filter condition to the blind parameter.

In addition, when the processor adds at least one fourth filter condition generated using the third filter condition to the query, the plurality of the plurality of EQCs included in the EQC list in the blind parameter of the third filter condition The at least one fourth filter condition may be generated by substituting at least one of the expressions.

In addition, the processor, when adding at least one fourth filter condition generated using the third filter condition to the query, at least one fifth filter to be added to the query using the third filter condition Create a condition, compare the at least one second filter condition and the at least one fifth filter condition included in the first list, and the at least one second filter condition and the at least one fifth filter condition The at least one fourth filter condition may be generated based on the comparison result.

Further, the processor may generate the at least one fourth filter condition based on a result of comparing the at least one second filter condition and the at least one fifth filter condition, the at least one second filter condition The filter condition and the at least one fifth filter condition may be compared to distinguish between the same filter condition and the non-identical filter condition, and the non-identical filter condition may be recognized as the at least one fourth filter condition.

Further, the processor, when the second filter condition includes the fourth filter condition, deletes the second filter condition from the same join operation in the query, and the second filter condition is the fourth filter condition If not included, the second filter condition may be maintained in the same join operation in the query.

In addition, the processor, when adding the at least one fourth filter condition to the query, rewrites the query by reflecting the at least one fourth filter condition in the query including the at least one join operation ( rewriting) can be done.

In addition, each of the first filter condition, the second filter condition, the third filter condition, and the fourth filter condition is a comparison condition of at least one expression and a specific value, a condition that is the same between at least one expression and a specific value, and It may include at least one of at least one expression and a non-equal condition of a specific value.

Technical solutions obtainable in the present disclosure are not limited to the above-mentioned solutions, and other solutions that are not mentioned are clearly to those of ordinary skill in the technical field to which the present disclosure belongs from the following description. It will be understandable.

The present disclosure may provide a database server and a computer program that perform optimization operations for a database query using an expression included in the same join operation.

The effects obtainable in the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those of ordinary skill in the art from the following description. .

Various aspects are now described with reference to the drawings, wherein like reference numbers are used collectively to refer to like elements. In the examples that follow, for illustrative purposes, a number of specific details are presented to provide a holistic understanding of one or more aspects. However, it will be apparent that such aspect(s) may be practiced without these specific details.
1 is a block diagram of a database server according to some embodiments of the present disclosure.
2 is a flowchart illustrating an example of a method of processing a query received from a client by a database server according to some embodiments of the present disclosure.
3 is a diagram for describing an example of a query, an EQC list, a first list, a second list, and a fifth filter condition according to some embodiments of the present disclosure.
4 is a flowchart illustrating an example of a method of generating a second filter condition by a database server according to some embodiments of the present disclosure.
5 is a flowchart illustrating an example of a method for the database server to recognize a fourth filter condition according to some embodiments of the present disclosure.
6 is a flowchart illustrating an example of a method of managing a second filter condition by a database server according to some embodiments of the present disclosure.
7 shows a simplified and general schematic diagram of an exemplary computing environment in which some embodiments of the present disclosure may be implemented.

Various embodiments and/or aspects are now disclosed with reference to the drawings. In the following description, for illustrative purposes, a number of specific details are disclosed to aid in an overall understanding of one or more aspects. However, it will also be appreciated by those of ordinary skill in the art that this aspect(s) may be practiced without these specific details. The following description and the annexed drawings set forth in detail certain illustrative aspects of one or more aspects. However, these aspects are exemplary and some of the various methods in the principles of the various aspects may be used, and the descriptions described are intended to include all such aspects and their equivalents. Specifically, as used herein, "an embodiment", "example", "aspect", "example" and the like are not construed as having any aspect or design being better or advantageous than other aspects or designs. May not.

In addition, various aspects and features will be presented by a system that may include one or more devices, terminals, servers, devices, components and/or modules, and the like. The devices, terminals, servers discussed in connection with the drawings, that various systems may include additional devices, terminals, servers, devices, components and/or modules, etc. It should also be understood and appreciated that it may not include all of devices, components, modules, etc.

The terms "computer program" "component", "module", "system" and the like as used herein may be used interchangeably, and computer-related entities, hardware, firmware, software, a combination of software and hardware, or Refers to the execution of software. For example, a component may be, but is not limited to, a process executed on a processor, a processor, an object, an execution thread, a program, and/or a computer. For example, both an application running on a computing device and a computing device may be components. One or more components may reside within a processor and/or thread of execution. A component can be localized on a single computer. A component can be distributed between two or more computers.

In addition, these components can execute from a variety of computer readable media having various data structures stored therein. Components can be, for example, via a signal with one or more data packets (e.g., data from one component interacting with another component in a local system, a distributed system, and/or signals through another system and a network such as the Internet. Depending on the data being transmitted), it may communicate via local and/or remote processes.

Hereinafter, the same or similar components are assigned the same reference numerals regardless of the reference numerals, and redundant descriptions thereof will be omitted. In addition, in describing the embodiments disclosed in the present specification, when it is determined that detailed descriptions of related known technologies may obscure the subject matter of the embodiments disclosed in the present specification, detailed descriptions thereof will be omitted. In addition, the accompanying drawings are for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the present specification is not limited by the accompanying drawings.

The terms used in the present specification are for describing exemplary embodiments and are not intended to limit the present disclosure. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, “comprises” and/or “comprising” do not exclude the presence or addition of one or more other elements other than the mentioned elements.

Although the first, second, etc. are used to describe various devices or components, it is a matter of course that these devices or components are not limited by these terms. These terms are only used to distinguish one device or component from another device or component. Therefore, it goes without saying that the first device or component mentioned below may be a second device or component within the spirit of the present disclosure.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings that can be commonly understood by those of ordinary skill in the art to which this disclosure belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise or is not clear from the context, "X employs A or B" is intended to mean one of the natural inclusive substitutions. That is, X uses A; X uses B; Or, when X uses both A and B, “X uses A or B” can be applied to either of these cases. In addition, the term "and/or" as used herein should be understood to refer to and include all possible combinations of one or more of the listed related items.

In addition, the terms “information” and “data” as used herein may often be used interchangeably with each other.

The suffixes “module” and “unit” for constituent elements used in the following description are given or used interchangeably in consideration of only the ease of preparation of the specification, and do not have distinct meanings or roles by themselves.

Objects and effects of the present disclosure, and technical configurations for achieving them will become apparent with reference to embodiments described in detail later with reference to the accompanying drawings. In describing the present disclosure, when it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the subject matter of the present disclosure, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present disclosure and may vary according to the intention or custom of users or operators.

However, the present disclosure is not limited to the embodiments disclosed below, and may be implemented in various different forms. The present embodiments are provided only to make the present disclosure complete, and to completely inform the scope of the disclosure to those of ordinary skill in the art to which the present disclosure belongs, and the present disclosure is only defined by the scope of the claims. . Therefore, the definition should be made based on the contents throughout this specification.

1 is a block diagram of a database server 100 according to some embodiments of the present disclosure.

Referring to FIG. 1, the database server 100 and the client 200 may mutually transmit and receive queries according to some embodiments of the present disclosure through a network.

In the present disclosure, a query refers to any request or command requesting processing in a database server, for example, Data Manipulation Language (DML), Data Definition Language (DDL), and/or PL/SQL ( Procedural Language/Structured Query Language), etc. may be included. In addition, a query in the present disclosure may mean an arbitrary request issued from a user/developer. In addition, the query may refer to an arbitrary request that is entered into the client 200 and/or the database server 100 and processed by the client 200 and/or the database server 100.

Networks according to some embodiments of the present disclosure include Public Switched Telephone Network (PSTN), x Digital Subscriber Line (xDSL), Rate Adaptive DSL (RADSL), Multi Rate DSL (MDSL), Very High Speed (VDSL). Various wired communication systems such as DSL), Universal Asymmetric DSL (UADSL), High Bit Rate DSL (HDSL), and local area network (LAN) can be used.

In addition, the network presented here is CDMA (Code Division Multi Access), TDMA (Time Division Multi Access), FDMA (Frequency Division Multi Access), OFDMA (Orthogonal Frequency Division Multi Access), SC-FDMA (Single Carrier-FDMA) and Various wireless communication systems such as other systems can be used.

The network according to the embodiments of the present disclosure may be configured regardless of its communication mode, such as wired and wireless, and is composed of various communication networks such as a personal area network (PAN) and a wide area network (WAN). Can be. In addition, the network may be a known World Wide Web (WWW), and may use a wireless transmission technology used for short-range communication such as infrared (IrDA: Infrared Data Association) or Bluetooth (Bluetooth).

The techniques described in this disclosure may be used not only in the networks mentioned above, but also in other networks.

According to some embodiments of the present disclosure, the database server 100 may include a communication unit 110, a storage unit 120, and a processor 130. However, the above-described components are not essential for implementing the database server 100, and the database server 100 may have more or fewer components than the components listed above.

The database server 100 may include any type of computer system or computer device, such as, for example, a microprocessor, mainframe computer, digital processor, portable device and device controller, and the like. The database server 100 may include a DBMS (Database Management System).

On the other hand, the client 200 is, for example, a personal computer (PC), a notebook (note book), a mobile terminal (mobile terminal), a smart phone (smart phone), a tablet PC (tablet PC), and a wearable device (wearable device). ) And the like, and may include all types of terminals that can access wired/wireless networks. In addition, the client 200 may transmit a query to the database server 100.

1 illustrates one database server 100 and one client 200 as an example, but more database servers (management devices) and clients 200 may also be included in the scope of the present invention. This will be apparent to those of ordinary skill in the field of application.

The communication unit 110 of the database server 100 may include one or more modules that enable communication between the database server 100 and a communication system, or between the database server 100 and the client 200. In addition, the communication unit 110 may include one or more modules that connect the database server 100 to one or more networks.

According to some embodiments of the present disclosure, the communication unit 110 of the database server 100 may receive a query including at least one join operation from the client 200.

In this case, the processor 130 of the database server 100 may recognize whether an equal join operation is included in the received query. When it is recognized that the received query includes the same join operation, the processor 130 may extract a plurality of expressions used for the same join operation. In addition, the processor 130 may generate an EQC (Equivalent Class) list including a plurality of expressions.

In the present disclosure, an expression may mean an expression included in a query received by the database server 100. This expression may include a table identification value of a data table stored in a permanent storage medium of a database and an identification value of a column or row in the table. For example, when the expression is't1.C', it may mean column C of table 1 in the data table.

In the present disclosure, the EQC list may mean a list of expressions corresponding to the same condition among expressions included in a query received by the database server 100. For example, when the same condition included in the query is'A = B,' each of'A' and'B' may be expressions corresponding to the same condition included in the query. In this case,'A' and'B' may be included in the EQC list.

Meanwhile, the processor 130 may extract at least one second filter condition related to a plurality of expressions included in the EQC list from among at least one first filter condition included in the query. Here, the second filter condition may be included in the first filter condition. In addition, the processor 130 may generate a first list including at least one second filter condition.

In the present disclosure, a filter condition means a condition for each of at least one expression included in a query. Specifically, a filter condition refers to a condition in a table that includes at least one expression included in the query. For example, the filter condition't1.A> 4'may be a filter condition that is satisfied when it is greater than '4' for a value included in the column'A' in table 1 t1.

A description of the method of generating the EQC list and the first list by the above-described processor 130 will be described in detail later with reference to FIGS. 2 and 3.

The processor 130 may analyze at least one second filter condition included in the first list by using the EQC list. Specifically, the processor 130 may generate a third filter condition related to the expression included in the EQC list.

Specifically, when the first sub-filter condition of the second filter condition includes the second sub-filter condition, the processor 130 generates a third filter condition by changing the second expression of the second sub-filter condition to a blind parameter. can do. Here, the first sub-filter condition may mean a filter condition in which the first expression is used among a plurality of expressions used for the same join operation included in the query. Also, the second sub-filter condition may mean a filter condition in which a second expression is used among the plurality of expressions.

In the present disclosure, the blind parameter means a parameter. Specifically, the blind parameter may be inserted at a position where a plurality of expressions can be substituted in one combined filter condition based on the same join condition and filter condition included in the query.

A description of a method of generating the third filter condition by the above-described processor 130 will be described in more detail later with reference to FIG. 4.

Meanwhile, the processor 130 may generate a second list including the third filter condition. In addition, the processor 130 may add at least one fourth filter condition generated by using the third filter condition to the received query.

Specifically, the processor 130 may rewrite the query by reflecting the fourth filter condition in the query including at least one join operation.

That is, the processor 130 of the database server 100 may optimize the query received from the client 200 as described above, and transmit it to a query executor.

The query executor receives and processes optimized queries, thereby reducing the load associated with query processing. Therefore, more efficient and accurate query processing may be possible.

A description of how the processor 130 adds the fourth filter condition to the received query will be described in detail later with reference to FIGS. 5 and 6.

In the present disclosure, each of the first filter condition, the second filter condition, the third filter condition, and the fourth filter condition is a comparison condition of at least one expression and a specific value, the same condition of at least one expression and a specific value, and at least one It may include at least one of an expression and a non-equal condition of a specific value. However, it is not limited thereto.

The storage unit 120 of the database server 100 may store a program for the operation of the processor 130 and may temporarily or permanently store input/output data. The storage unit 120 includes a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (eg, SD or XD memory, etc.), RAM (Random Access Memory, RAM), SRAM (Static Random Access Memory), ROM (Read-Only Memory, ROM), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, It may include at least one type of storage medium among magnetic disks and optical disks. The storage unit 120 may be operated under control by the processor 130.

Although not shown in FIG. 1, the storage unit 120 of the database server 100 may include a memory and a permanent storage medium. That is, the database server 100 may include one or more memories including a buffer cache. In this case, the DBMS may be operated by the processor 130 on the memory.

Here, the memory is the main storage device directly accessed by the processor, such as a random access memory (RAM) such as dynamic random access memory (DRAM) and static random access memory (SRAM), and stored information when the power is turned off. May mean a volatile storage device that is instantly erased, but is not limited thereto. Such a memory can be operated under control of the processor.

The memory may temporarily store a data table including data values. The data table may include data values, and in some embodiments of the present disclosure, the data values of the data table may be recorded from a memory to a permanent storage medium. Additionally, the memory of the storage unit 120 may include a buffer cache, and data may be stored in a data block of the buffer cache. The data may be recorded in a permanent storage medium of the storage unit 120 by a background process.

Persistent storage media include, for example, any data, such as magnetic disks, optical disks, and magneto-optical storage devices as well as storage devices based on flash memory and/or battery-backup memory. It refers to a non-volatile storage medium capable of continuously performing. Such a permanent storage medium may communicate with the processor 130 and the memory of the database server 100 through various communication means.

In an additional embodiment, such a permanent storage medium may be located outside the database server 100 to communicate with the database server 100.

The DBMS is a program for allowing the database server 100 to perform operations such as searching, inserting, modifying and/or deleting necessary data. As described above, the processor 130 in the memory of the database server 100 It can be implemented by

The processor 130 of the database server 100 typically controls the overall operation of the database server 100. The processor 130 may provide or process appropriate information or functions to a user by processing signals, data, information, etc. that are input or output through the above-described components, or by driving an application program stored in the storage unit 120. .

The processor 130 of the database server 100 may control at least some of the components described with reference to FIG. 1 in order to run an application program stored in the storage unit 120. Further, in order to drive the application program, the processor 130 may operate by combining at least two or more of the components included in the database server 100 with each other.

Various embodiments described herein may be implemented in a recording medium and a storage medium that can be read by a computer or a similar device using, for example, software, hardware, or a combination thereof.

According to hardware implementation, the embodiments described herein include application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), It may be implemented using at least one of processors, controllers, micro-controllers, microprocessors, and electrical units for performing other functions, in some cases herein. The described embodiments may be implemented by the processor 130 itself.

According to the software implementation, embodiments such as procedures and functions described in the present specification may be implemented as separate software modules. Each of the software modules may perform one or more functions and operations described herein. The software code can be implemented as a software application written in an appropriate programming language. The software code may be stored in the storage unit 120 and executed by the processor 130.

2 is a flowchart illustrating an example of a method of processing a query received from a client by a database server according to some embodiments of the present disclosure. 3 is a diagram for describing an example of a query, an EQC list, a first list, a second list, and a fifth filter condition according to some embodiments of the present disclosure.

Referring to FIG. 2, the processor 130 of the database server 100 may receive a query through the communication unit 110 (S100 ). Specifically, the processor 130 may receive the query 10 including at least one join operation as illustrated in FIG. 3. Here, the query 10 including at least one join operation may include the same join operation 11 and a first filter condition 12. However, it is not limited thereto.

Referring back to FIG. 2, the processor 130 may recognize whether the query 10 includes an equal join operation (S200). Here, the equal join operation means an operation in which the first expression and the second expression used in the query are equivalent. For example,'t1.C = t2.B' as shown in FIG. 3 may be an equal join operation.

When it is recognized that the same join operation is not included in the query 10 (S200, No), the processor 130 may maintain the query so that it is processed as it is without extracting a plurality of expressions used in the join operation.

Meanwhile, when it is recognized that the query 10 includes the same join operation (S200, Yes), the processor 130 may extract a plurality of expressions used in the same join operation. In addition, the processor 130 may generate an EQC (Equivalent Class) list including a plurality of expressions (S300).

For example, referring to FIG. 3, the processor 130 may recognize't1.C = t2.B', which is an equal join operation 11 included in the query 10. In addition, the processor 130 may extract expressions't1.C' and't2.B' used in the same join operation 11. Further, the processor 130 may generate the EQC list 20 including the expressions't1.C' and't2.B' used in the same join operation 11.

Referring back to FIG. 2, the processor 130 of the database server 100 may extract at least one second filter condition related to a plurality of expressions included in the EQC list from among the first filter conditions. Also, the processor 130 may generate a first list including at least one second filter condition (S400).

For example, referring to FIG. 3, the processor 130 includes expressions 21 included in the EQC list 20 among the first filter conditions 12 included in the query 10,'t1.C' and ' The second filter condition 31 related to t2.B' can be extracted. That is, the processor 130 may extract't2.B = 3', which is a filter related to't2.B'. In addition, the processor 130 may extract't1.C> 2', which is a filter related to't1.C'. In addition, the processor 130 may generate a first list 30 including the extracted filters't2.B = 3'and't1.C> 2'.

Referring back to FIG. 2, the processor 130 of the database server 100 may analyze at least one second filter condition included in the first list by using the EQC list. Also, the processor 130 may generate a third filter condition by analyzing the second filter condition.

For example, referring to FIG. 3, the processor 130 may generate the third filter condition 41 in which the L-value is changed to the blind parameter 42.

In the present disclosure, the L-value may be a value at which an expression is located in a filter condition included in a query. For example, when the filter condition included in the query is'A = 3','A' may be an L-value. Meanwhile, '3' may be an R-value. That is, the left value of the substitution statement (here, the third filter condition in which the L-value is changed to the blind parameter) is the L-value, and the right value of the substitution statement is the R-value. I can.

A description of the method of generating the third filter condition by the above-described processor 130 will be described in detail later with reference to FIG. 4.

Referring back to FIG. 2, the processor 130 of the database server 100 may generate a second list including the third filter condition (S500 ). Further, the processor 130 may add at least one fourth filter condition generated by using the third filter condition to the query (S600).

For example, referring to FIG. 3, the processor 130 may generate a fifth filter condition 50 to be added to the query 10 by using the third filter condition 41. Also, the processor 130 may determine a fourth filter condition 60 to be added to the query 10 from among the fifth filter conditions.

Specifically, the processor 130 may recognize a fourth filter condition 60 different from the first filter condition included in the query 10 among the fifth filter conditions 50. In addition, the processor 130 may add the fourth filter condition 60 to the query 10.

That is, the processor 130 may rewrite the query 10 by reflecting the fourth filter condition 60 in the query 10 including at least one join operation.

4 is a flowchart illustrating an example of a method of generating a second filter condition by a database server according to some embodiments of the present disclosure.

First, referring to FIG. 2, the processor 130 of the database server 100 uses at least one second list included in the first list by using the EQC list to generate a second list including the third filter condition. Filter conditions can be analyzed.

Specifically, referring to FIG. 4, the processor 130 may compare a first sub-filter condition and a second sub-filter condition of the second filter condition. More specifically, the processor 130 may recognize whether the first sub-filter condition is included in the second sub-filter condition (S520).

In the present disclosure, the meaning that the first condition includes the second condition may mean that the first range corresponding to the first condition is larger than the second range corresponding to the second condition. For example, when the first condition is'A> 3'and the second condition is'A> 5', it may be expressed that the first condition includes the second condition. As another example, when the first condition is'B> 4'and the second condition is'B = 7', it may be expressed that the first condition includes the second condition.

When the first sub-filter condition includes the second sub-filter condition (S520, Yes), the processor 130 may generate a third filter condition by changing the second expression of the second sub-filter condition to a blind parameter. (S530).

For example, in the processor 130, each of't1.C' and't2.B' is the same by the same join operation of't1.C = t2.B', and the first sub-filter condition is't1.C>' When 2'and the second sub-filter condition is't2.B = 3', it may be recognized that the first sub-filter condition includes the second sub-filter condition.

In addition, the processor 130 may change the second expression of the second sub-filter condition included in the first sub-filter condition into a blind parameter (eg,'?'). That is, the processor 130 changes't2.B', which is the second expression of't2.B = 3', which is the second sub-filter condition, into a blind parameter, and changes the'? A third filter condition of = 3'can be created.

Meanwhile, when the first sub-filter condition is not included in the second sub-filter condition (S520, No), the processor 130 may recognize that the second sub-filter condition includes the first sub-filter condition (S540). . In addition, the processor 130 may generate a third filter condition by changing the first expression of the first sub-filter condition into a blind parameter (S550).

For example, in the processor 130, each of't1.C' and't2.B' is the same through the same join operation of't1.C = t2.B', and the first sub-filter condition is't2.C =' If 3'and the second sub-filter condition is't1.B> 2', it may be recognized that the second sub-filter condition includes the first sub-filter condition.

Further, the processor 130 may change the first expression of the first sub-filter condition included in the second sub-filter condition into a blind parameter. That is, the processor 130 changes't2.C', which is the first expression of't2.C = 3', which is the first sub-filter condition, into a blind parameter, and changes the'? A third filter condition of = 3'can be created.

Meanwhile, the processor 130 may generate a second list including the third filter condition. In addition, the processor 130 may generate a fourth filter condition by using the third filter condition included in the second list. In this case, the processor 130 may add the fourth filter condition to the query received from the client 200.

A detailed description of the method of generating the fourth filter condition by the above-described processor 130 will be described later in detail with reference to FIG. 5.

5 is a flowchart illustrating an example of a method for the database server to recognize a fourth filter condition according to some embodiments of the present disclosure.

First, referring to FIG. 2, the processor 130 of the database server 100 may generate a fourth filter condition by using a third filter condition included in the second list page. Also, the processor 130 may add the fourth filter condition to the query.

Specifically, referring to FIG. 5, the processor 130 of the database server 100 may generate at least one fifth filter condition to be added to the query by using the third filter condition (S610). More specifically, the processor 130 may generate the fifth filter condition by substituting at least one expression included in the EQC list into the blind parameter of the third filter condition.

For example, the processor 130, the third filter condition'? = 3'and the expressions included in the EQC list are't1.C' and't2.B', each of't1.C' and't2.B' is added to the blind parameter'?' of the third filter condition. Substituting, a fifth filter condition can be generated. That is, the processor 130 may generate the fifth filter condition of't1.C = 3'and't2.B = 3'.

In other words, since the plurality of expressions included in the EQC list are used in the same join operation with each other, the third filter condition generated based on the filter condition associated with each of the plurality of expressions may be met.

Accordingly, when a plurality of expressions included in the EQC list are substituted into the blind parameter of the third filter condition, it may be a filter condition that derives the same result as the result of the filter condition of the query received from the client 200.

Specifically, the processor 130 may generate a new filter condition capable of deriving the same result as the result derived through at least two calculation processes for the filter condition included in the query received from the client 200. Here, the new filter condition may derive the same result through one operation process.

Accordingly, the processor 130 may reduce the load caused by query processing. Therefore, more efficient and accurate query processing may be possible.

That is, the processor 130 may add the fifth filter condition generated by substituting the expression included in the EQC list into the blind parameter of the third filter condition to the query received from the client 200.

Meanwhile, the processor 130 of the database server 100 may compare at least one second filter condition and at least one fifth filter condition included in the first list (S620).

When the comparison result of the at least one second filter condition and the at least one fifth filter condition is a non-identical filter condition (S630, Yes), the processor 130 recognizes the non-identical filter condition as at least one fourth filter condition. Can do it (S640).

Specifically, when at least one second filter condition and at least one fifth filter condition are non-identical filter conditions, the processor 130 may recognize that the fifth filter condition is a filter condition that does not exist in the query. Also, the processor 130 may recognize the fifth filter condition that does not exist in the query as the fourth filter condition and add it to the query.

More specifically, the processor 130 may rewrite the query by reflecting the fourth filter condition in the query including at least one join operation.

Meanwhile, when the comparison result of the at least one second filter condition and at least one fifth filter condition is the same filter condition (S630, No), the processor 130 of the database server 100 may perform at least one fifth filter condition. May not be recognized as the fourth filter condition.

That is, the processor 130 may not add the fifth filter condition already existing in the query to the query. Accordingly, the processor 130 may simplify a process for query processing by preventing the generation of redundant filter conditions.

6 is a flowchart illustrating an example of a method of managing a second filter condition by a database server according to some embodiments of the present disclosure.

First, referring to FIG. 2, the processor 130 of the database server 100 may generate a fourth filter condition by using a third filter condition included in the second list page. Also, the processor 130 may add the fourth filter condition to the query.

Referring to FIG. 6, after the fourth filter condition is added to the query, the processor 130 of the database server 100 may compare the second filter condition and the fourth filter condition (S710).

Specifically, the processor 130 of the database server 100 may recognize whether the second filter condition includes the fourth filter condition (S720). Here, the meaning that the first condition includes the second condition may mean that the first range corresponding to the first condition is larger than the second range corresponding to the second condition. For example, when the first condition is'A> 3'and the second condition is'A> 5', it may be expressed that the first condition includes the second condition. As another example, when the first condition is'B> 4'and the second condition is'B = 7', it may be expressed that the first condition includes the second condition.

Meanwhile, assuming that the second filter condition includes the fourth filter condition, when the first expression meets the fourth filter condition, the second filter condition is also met. That is, if it is checked whether the fourth filter condition is satisfied with respect to the first expression, there is no need to go through a process of checking whether the second filter condition is satisfied.

Accordingly, when the processor 130 of the database server 100 recognizes that the second filter condition includes the fourth filter condition (S720, Yes), the second filter condition may be deleted from the same join operation in the query (S730). ).

For example, the processor 130 includes't2.B = 3'and't1.C> 2'as second filter conditions in the first list, and't1.C = 3'as the fourth filter condition. In the case of', it may be recognized that the second filter condition't1.C> 2'includes the fourth filter condition't1.C = 3'. In this case, the processor 130 may delete the second filter condition including the fourth filter condition.

That is, the processor 130 may delete a filter condition having a wider range corresponding to the filter condition among various filter conditions associated with the same expression, thereby reducing the process of checking whether the filter condition is met.

On the other hand, when the processor 130 of the database server 100 recognizes that the second filter condition does not include the fourth filter condition (S720, No), the second filter condition may be maintained in the same join operation in the query. (S740).

That is, the processor 130 may recognize whether each of the second filter condition and the fourth filter condition can be combined. Meanwhile, the processor 130 may not delete the second filter condition so that each of the second filter condition and the fourth filter condition, which cannot be combined, exist in the query.

7 shows a simplified and general schematic diagram of an exemplary computing environment in which embodiments of the present disclosure may be implemented.

While the present disclosure has generally been described above with respect to computer-executable instructions that can be executed on one or more computers, those skilled in the art will appreciate that the present disclosure may be implemented in combination with other program modules and/or as a combination of hardware and software. will be.

In general, modules herein include routines, procedures, programs, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Further, to those skilled in the art, the method of the present disclosure is a single-processor or multiprocessor computer system, a minicomputer, a main frame computer as well as a personal computer, handheld computing device, microprocessor-based or programmable household appliance, etc. It will be appreciated that it may be implemented with other computer system configurations, including one or more associated devices).

The described embodiments of the present disclosure may also be practiced in a distributed computing environment where certain tasks are performed by remote processing devices that are connected through a communication network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

Computers typically include a variety of computer-readable media. Computer-readable media can be any computer-readable media, including volatile and non-volatile media, transitory and non-transitory media, removable and non-transitory media. Includes removable media. By way of example, and not limitation, computer-readable media may include computer-readable storage media and computer-readable transmission media.

Computer-readable storage media include volatile and nonvolatile media, transitory and non-transitory media, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Includes the medium. Computer-readable storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital video disk (DVD) or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage. Devices, or any other medium that can be accessed by a computer and used to store desired information.

Computer-readable transmission media typically implement computer-readable instructions, data structures, program modules or other data on a modulated data signal such as a carrier wave or other transport mechanism. Includes all information transmission media. The term modulated data signal refers to a signal in which one or more of the characteristics of the signal is set or changed to encode information in the signal. By way of example, and not limitation, computer-readable transmission media include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above-described media are also intended to be included within the scope of computer-readable transmission media.

An exemplary environment 1100 is shown that implements various aspects of the present disclosure, including a computer 1102, which includes a processing device 1104, a system memory 1106, and a system bus 1108. do. System bus 1108 couples system components, including but not limited to, system memory 1106 to processing device 1104. The processing unit 1104 may be any of a variety of commercially available processors. Dual processors and other multiprocessor architectures may also be used as processing unit 1104.

The system bus 1108 may be any of several types of bus structures that may be additionally interconnected to a memory bus, a peripheral bus, and a local bus using any of a variety of commercial bus architectures. System memory 1106 includes read-only memory (ROM) 1110 and random access memory (RAM) 1112. The basic input/output system (BIOS) is stored in non-volatile memory 1110 such as ROM, EPROM, EEPROM, etc. This BIOS is a basic input/output system that helps transfer information between components in the computer 1102, such as during startup. Includes routines. RAM 1112 may also include high-speed RAM, such as static RAM, for caching data.

Computer 1102 also includes internal hard disk drive (HDD) 1114 (e.g., EIDE, SATA)-This internal hard disk drive 1114 can also be configured for external use within a suitable chassis (not shown). Yes--, magnetic floppy disk drive (FDD) 1116 (for example, to read from or write to removable diskette 1118), and optical disk drive 1120 (e.g., CD-ROM To read the disk 1122 or read from or write to other high-capacity optical media such as DVD). The hard disk drive 1114, magnetic disk drive 1116, and optical disk drive 1120 are each connected to the system bus 1108 by a hard disk drive interface 1124, a magnetic disk drive interface 1126, and an optical drive interface 1128. ) Can be connected. The interface 1124 for implementing an external drive includes, for example, at least one or both of USB (Universal Serial Bus) and IEEE 1394 interface technologies.

These drives and their associated computer readable media provide non-volatile storage of data, data structures, computer executable instructions, and the like. In the case of computer 1102, drives and media correspond to storing any data in a suitable digital format. Although the description of the computer-readable storage medium above refers to a removable optical medium such as a HDD, a removable magnetic disk, and a CD or DVD, those skilled in the art may include a zip drive, a magnetic cassette, a flash memory card, a cartridge, It will be appreciated that other types of computer-readable storage media, such as etc., may also be used in the exemplary operating environment and that any such media may contain computer-executable instructions for performing the methods of the present disclosure. .

A number of program modules, including the operating system 1130, one or more application programs 1132, other program modules 1134, and program data 1136, may be stored in the drive and RAM 1112. All or part of the operating system, applications, modules, and/or data may also be cached in RAM 1112. It will be appreciated that the present disclosure may be implemented on a number of commercially available operating systems or combinations of operating systems.

A user may input commands and information to the computer 1102 through one or more wired/wireless input devices, for example, a pointing device such as a keyboard 1138 and a mouse 1140. Other input devices (not shown) may include a microphone, IR remote control, joystick, game pad, stylus pen, touch screen, and the like. These and other input devices are often connected to the processing unit 1104 through the input device interface 1142, which is connected to the system bus 1108, but the parallel port, IEEE 1394 serial port, game port, USB port, IR interface, It can be connected by other interfaces such as etc.

A monitor 1144 or other type of display device is also connected to the system bus 1108 through an interface such as a video adapter 1146. In addition to the monitor 1144, the computer generally includes other peripheral output devices (not shown) such as speakers, printers, etc.

Computer 1102 may operate in a networked environment using logical connections to one or more remote computers, such as remote computer(s) 1148 via wired and/or wireless communication. The remote computer(s) 1148 may be a workstation, server computer, router, personal computer, portable computer, microprocessor-based entertainment device, peer device, or other common network node, and is generally referred to as a computer 1102. Although including many or all of the described components, only memory storage device 1150 is shown for simplicity. The logical connections shown include wired/wireless connections to a local area network (LAN) 1152 and/or to a larger network, eg, a wide area network (WAN) 1154. Such LAN and WAN networking environments are common in offices and companies, and facilitate an enterprise-wide computer network such as an intranet, all of which can be connected to a worldwide computer network, for example the Internet.

When used in a LAN networking environment, the computer 1102 is connected to the local network 1152 via a wired and/or wireless communication network interface or adapter 1156. Adapter 1156 may facilitate wired or wireless communication to LAN 1152, which also includes a wireless access point installed therein to communicate with wireless adapter 1156. When used in a WAN networking environment, the computer 1102 may include a modem 1158, connected to a communication server on the WAN 1154, or through the Internet, etc. to establish communication through the WAN 1154 Have means. The modem 1158, which may be an internal or external and a wired or wireless device, is connected to the system bus 1108 through a serial port interface 1142. In a networked environment, program modules described for the computer 1102 or portions thereof may be stored in the remote memory/storage device 1150. It will be appreciated that the network connections shown are exemplary and other means of establishing communication links between computers may be used.

Computer 1102 is associated with any wireless device or entity deployed and operated in wireless communication, e.g., a printer, scanner, desktop and/or portable computer, portable data assistant (PDA), communication satellite, wireless detectable tag. It operates to communicate with any equipment or place and phone. This includes at least Wi-Fi and Bluetooth wireless technologies. Thus, the communication may be a predefined structure as in a conventional network or may simply be ad hoc communication between at least two devices.

Wi-Fi (Wireless Fidelity) allows you to connect to the Internet, etc. without wires. Wi-Fi is a wireless technology such as a cell phone that allows such devices, for example computers, to transmit and receive data indoors and outdoors, ie anywhere within the coverage area of a base station. Wi-Fi networks use a wireless technology called IEEE 802.11 (a,b,g, etc.) to provide a secure, reliable and high-speed wireless connection. Wi-Fi can be used to connect computers to each other, to the Internet and to a wired network (using IEEE 802.3 or Ethernet). Wi-Fi networks can operate in unlicensed 2.4 and 5 GHz radio bands, for example at 11 Mbps (802.11a) or 54 Mbps (802.11b) data rates, or in products that include both bands (dual band). have.

A person of ordinary skill in the art of the present disclosure includes various exemplary logical blocks, modules, processors, means, circuits and algorithm steps described in connection with the embodiments disclosed herein, electronic hardware, (convenience). For the sake of clarity, it will be appreciated that it may be implemented by various forms of program or design code or a combination of both (referred to herein as "software"). To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. A person of ordinary skill in the art of the present disclosure may implement the described functions in various ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various embodiments presented herein may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term “article of manufacture” includes a computer program or media accessible from any computer-readable device. For example, computer-readable storage media include magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical disks (e.g., CD, DVD, etc.), smart cards, and flash Memory devices (eg, EEPROMs, cards, sticks, key drives, etc.), but are not limited thereto. The term “machine-readable medium” includes, but is not limited to, wireless channels and various other media capable of storing, holding, and/or transmitting instruction(s) and/or data.

It is to be understood that the specific order or hierarchy of steps in the presented processes is an example of exemplary approaches. Based on the design priorities, it is to be understood that within the scope of the present disclosure a specific order or hierarchy of steps in processes may be rearranged. The appended method claims provide elements of the various steps in a sample order, but are not meant to be limited to the specific order or hierarchy presented.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be apparent to those of ordinary skill in the art, and general principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the embodiments presented herein, but is to be interpreted in the widest scope consistent with the principles and novel features presented herein.

Claims (18)

A computer program stored on a computer-readable storage medium, comprising:
The computer program includes instructions for causing a processor of the database server to perform optimization operations for a database query, the operations:
Receiving a query including at least one join operation;
Extracting a plurality of expressions used in the same join operation when the query includes an equal join operation;
Generating an EQC (Equivalent Class) list including the plurality of expressions;
Extracting at least one second filter condition related to the plurality of expressions included in the EQC list from among at least one first filter condition included in the query;
Generating a first list including the at least one second filter condition;
As the at least one second filter condition included in the first list is analyzed using the EQC list, some of the expressions included in the second filter condition among the plurality of expressions included in the EQC list are blinded parameters. Generating a third filter condition changed to;
Generating a second list including the third filter condition; And
Adding at least one fourth filter condition generated by substituting at least one of the plurality of expressions included in the EQC list into the blind parameter of the third filter condition to the query;
Containing,
A computer program stored on a computer-readable storage medium.
The method of claim 1,
The at least one second filter condition,
A first sub-filter condition in which a first expression is used among the plurality of expressions and a second sub-filter condition in which a second expression is used among the plurality of expressions,
The operation of generating the third filter condition,
Comparing the first sub-filter condition and the second sub-filter condition; And
Generating the third filter condition based on a comparison result of the first sub-filter condition and the second sub-filter condition;
Containing,
A computer program stored on a computer-readable storage medium.
The method of claim 2,
The operation of generating the third filter condition based on the comparison result of the first sub-filter condition and the second sub-filter condition,
Generating the third filter condition by changing the second expression of the second sub-filter condition to the blind parameter when the first sub-filter condition includes the second sub-filter condition; And
Generating the third filter condition by changing the first expression of the first sub-filter condition to the blind parameter when the second sub-filter condition includes the first sub-filter condition;
Containing,
A computer program stored on a computer-readable storage medium.

delete The method of claim 1,
The operation of adding the at least one fourth filter condition to the query,
Generating at least one fifth filter condition to be added to the query by using the third filter condition;
Comparing the at least one second filter condition and the at least one fifth filter condition included in the first list; And
Generating the at least one fourth filter condition based on a result of comparing the at least one second filter condition and the at least one fifth filter condition;
Containing,
A computer program stored on a computer-readable storage medium.
The method of claim 5,
Based on a result of comparing the at least one second filter condition and the at least one fifth filter condition, generating the at least one fourth filter condition,
Comparing the at least one second filter condition and the at least one fifth filter condition to distinguish between the same filter condition and the non-identical filter condition; And
Recognizing the non-identical filter condition as the at least one fourth filter condition;
Containing,
A computer program stored on a computer-readable storage medium.
The method of claim 1,
If the second filter condition includes the fourth filter condition, deleting the second filter condition from the same join operation in the query; And
If the second filter condition does not include the fourth filter condition, maintaining the second filter condition in the same join operation in the query;
Further comprising,
A computer program stored on a computer-readable storage medium.
The method of claim 1,
The operation of adding the at least one fourth filter condition to the query,
Rewriting the query by reflecting the at least one fourth filter condition in the query including the at least one join operation;
Containing,
A computer program stored on a computer-readable storage medium.
The method of claim 1,
Each of the first filter condition, the second filter condition, the third filter condition, and the fourth filter condition,
Comprising at least one of a comparison condition of at least one expression and a specific value, an equal condition of at least one expression and a specific value, and a non-equal condition of at least one expression and a specific value,
A computer program stored on a computer-readable storage medium.
As a database server,
A communication unit for receiving a query including at least one join operation; And
A processor for optimizing the query;
Including,
The processor,
When the query includes an equal join operation, extracting a plurality of expressions used in the equal join operation,
Create an EQC (Equivalent Class) list including the plurality of expressions,
Extracting at least one second filter condition related to the plurality of expressions included in the EQC list from among at least one first filter condition included in the query,
Generating a first list including the at least one second filter condition,
As the at least one second filter condition included in the first list is analyzed using the EQC list, some of the expressions included in the second filter condition among the plurality of expressions included in the EQC list are blinded parameters. Create a third filter condition changed to,
Generating a second list including the third filter condition,
Adding at least one fourth filter condition generated by substituting at least one of the plurality of expressions included in the EQC list into the blind parameter of the third filter condition to the query,
Database server.
The method of claim 10,
The at least one second filter condition,
A first sub-filter condition in which a first expression is used among the plurality of expressions and a second sub-filter condition in which a second expression is used among the plurality of expressions,
The processor,
When generating the third filter condition, comparing the first sub-filter condition and the second sub-filter condition,
Generating the third filter condition based on the comparison result of the first sub filter condition and the second sub filter condition,
Database server.
The method of claim 11,
The processor,
When the first sub-filter condition includes the second sub-filter condition, the second expression of the second sub-filter condition is changed to the blind parameter to generate the third filter condition, and
When the second sub-filter condition includes the first sub-filter condition, generating the third filter condition by changing the first expression of the first sub-filter condition to the blind parameter,
Database server.
delete The method of claim 10,
The processor,
When adding the at least one fourth filter condition to the query, at least one fifth filter condition to be added to the query is generated using the third filter condition,
Comparing the at least one second filter condition and the at least one fifth filter condition included in the first list,
Generating the at least one fourth filter condition based on a result of comparing the at least one second filter condition with the at least one fifth filter condition,
Database server.
The method of claim 14,
The processor,
When generating the at least one fourth filter condition based on a result of comparing the at least one second filter condition and the at least one fifth filter condition, the at least one second filter condition and the at least one By comparing the fifth filter condition of, the same filter condition and the non-identical filter condition are distinguished,
Recognizing the non-identical filter condition as the at least one fourth filter condition,
Database server.
The method of claim 10,
The processor,
If the second filter condition includes the fourth filter condition, delete the second filter condition from the same join operation in the query,
If the second filter condition does not include the fourth filter condition, maintaining the second filter condition in the same join operation in the query,
Database server.
The method of claim 10,
The processor,
When the at least one fourth filter condition is added to the query, rewriting the query by reflecting the at least one fourth filter condition in a query including the at least one join operation,
Database server.
The method of claim 10,
Each of the first filter condition, the second filter condition, the third filter condition, and the fourth filter condition,
Comprising at least one of a comparison condition of at least one expression and a specific value, an equal condition of at least one expression and a specific value, and a non-equal condition of at least one expression and a specific value,
Database server.

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