Patent Publication Number: US-2023153300-A1

Title: Building cross table index in relational database

Description:
BACKGROUND 
     The present disclosure relates to database management, and, more specifically, to building and utilizing a cross table index to reduce computational costs. 
     Modern database systems can contain relatively large amounts of data. This data can be processed, updated, retrieved, and/or otherwise used for many purposes. Queries can be used to process the data. Queries are generally written to conform to the structure of a database. A single query can retrieve data from multiple data sources, which can result in a variety of potential flow paths to execute the query. 
     SUMMARY 
     Disclosed is a computer-implemented method to generate and utilize a hybrid index. The method includes receiving a first query, wherein the first query is configured to perform a first command. The method further includes generating a hybrid index, wherein the hybrid index defines a connection between a first table and a second table of a set of tables. The method also includes executing the first query using the hybrid index. The method includes returning a set of results for the first query to a source of the query. Further aspects of the present disclosure are directed to systems and computer program products containing functionality consistent with the method described above. 
     The present Summary is not intended to illustrate each aspect of, every implementation of, and/or every embodiment of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments are described herein with reference to different subject-matter. In particular, some embodiments may be described with reference to methods, whereas other embodiments may be described with reference to apparatuses and systems. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one type of subject-matter, also any combination between features relating to different subject-matter, in particular, between features of the methods, and features of the apparatuses and systems, are considered as to be disclosed within this document. 
       The aspects defined above, and further aspects disclosed herein, are apparent from the examples of one or more embodiments to be described hereinafter and are explained with reference to the examples of the one or more embodiments, but to which the invention is not limited. Various embodiments are described, by way of example only, and with reference to the following drawings: 
         FIG.  1    depicts a cloud computing environment according to an embodiment of the present invention. 
         FIG.  2    depicts abstraction model layers according to an embodiment of the present invention. 
         FIG.  3    is a block diagram of a DPS according to one or more embodiments disclosed herein. 
         FIG.  4    is a functional diagram of a computing environment suitable for operation of a hybrid index in accordance with some embodiments of the present disclosure. 
         FIG.  5    includes a structure for a hybrid index in accordance with some embodiments of the present disclosure. 
         FIG.  6    includes an example instruction to generate and an example layout of a hybrid index in accordance with some embodiments of the present disclosure. 
         FIG.  7    is a flow chart of an example method to generate and use a hybrid index, in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Cloud Computing in General 
     It is to be understood that although this disclosure includes a detailed description on cloud computing, implementation of the teachings recited herein are not limited to a cloud computing environment. Rather, embodiments of the present invention are capable of being implemented in conjunction with any other type of computing environment now known or later developed. 
     Cloud computing is a model of service delivery for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, network bandwidth, servers, processing, memory, storage, applications, virtual machines, and services) that can be rapidly provisioned and released with minimal management effort or interaction with a provider of the service. This cloud model may include at least five characteristics, at least three service models, and at least four deployment models. 
     Characteristics are as follows 
     On-demand self-service: a cloud consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with the service&#39;s provider. 
     Broad network access: capabilities are available over a network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and personal digital assistants (PDAs)). 
     Resource pooling: the provider&#39;s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to demand. There is a sense of location independence in that the consumer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). 
     Rapid elasticity: capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out and rapidly released to quickly scale in. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time. 
     Measured service: cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service. 
     Service Models are as follows 
     Software as a Service (SaaS): the capability provided to the consumer is to use the provider&#39;s applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based e-mail). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings. 
     Platform as a Service (PaaS): the capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including networks, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations. 
     Infrastructure as a Service (IaaS): the capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls). 
     Deployment Models are as follows 
     Private cloud: the cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on-premises or off-premises. 
     Community cloud: the cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on-premises or off-premises. 
     Public cloud: the cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services. 
     Hybrid cloud: the cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load-balancing between clouds). 
     A cloud computing environment is service oriented with a focus on statelessness, low coupling, modularity, and semantic interoperability. At the heart of cloud computing is an infrastructure that includes a network of interconnected nodes. 
     Referring now to  FIG.  1   , illustrative cloud computing environment  50  is depicted. As shown, cloud computing environment  50  includes one or more cloud computing nodes  10  with which local computing devices used by cloud consumers, such as, for example, personal digital assistant (PDA) or cellular telephone  54 A, desktop computer  54 B, laptop computer  54 C, and/or automobile computer system  54 N may communicate. Nodes  10  may communicate with one another. They may be grouped (not shown) physically or virtually, in one or more networks, such as Private, Community, Public, or Hybrid clouds as described hereinabove, or a combination thereof. This allows cloud computing environment  50  to offer infrastructure, platforms and/or software as services for which a cloud consumer does not need to maintain resources on a local computing device. It is understood that the types of computing devices  54 A-N shown in Figurel are intended to be illustrative only and that computing nodes  10  and cloud computing environment  50  can communicate with any type of computerized device over any type of network and/or network addressable connection (e.g., using a web browser). 
     Referring now to  FIG.  2   , a set of functional abstraction layers provided by cloud computing environment  50  ( FIG.  1   ) is shown. It should be understood in advance that the components, layers, and functions shown in  FIG.  2    are intended to be illustrative only and embodiments of the invention are not limited thereto. As depicted, the following layers and corresponding functions are provided: 
     Hardware and software layer  60  includes hardware and software components. 
     Examples of hardware components include: mainframes  61 ; RISC (Reduced Instruction Set Computer) architecture based servers  62 ; servers  63 ; blade servers  64 ; storage devices  65 ; and networks and networking components  66 . In some embodiments, software components include network application server software  67  and database software  68 . 
     Virtualization layer  70  provides an abstraction layer from which the following examples of virtual entities may be provided: virtual servers  71 ; virtual storage  72 ; virtual networks  73 , including virtual private networks; virtual applications and operating systems  74 ; and virtual clients  75 . 
     In one example, management layer  80  may provide the functions described below. Resource provisioning  81  provides dynamic procurement of computing resources and other resources that are utilized to perform tasks within the cloud computing environment. Metering and Pricing  82  provide cost tracking as resources are utilized within the cloud computing environment, and billing or invoicing for consumption of these resources. In one example, these resources may include application software licenses. Security provides identity verification for cloud consumers and tasks, as well as protection for data and other resources. User portal  83  provides access to the cloud computing environment for consumers and system administrators. Service level management  84  provides cloud computing resource allocation and management such that required service levels are met. Service Level Agreement (SLA) planning and fulfillment  85  provide pre-arrangement for, and procurement of, cloud computing resources for which a future requirement is anticipated in accordance with an SLA. 
     Workloads layer  90  provides examples of functionality for which the cloud computing environment may be utilized. Examples of workloads and functions which may be provided from this layer include: mapping and navigation  91 ; software development and lifecycle management  92 ; virtual classroom education delivery  93 ; data analytics processing  94 ; transaction processing  95 ; and hybrid indices  96 . 
     Data Processing System in General 
       FIG.  3    is a block diagram of an example data processing system (DPS) according to one or more embodiments. The DPS may be used as a cloud computing node  10 . In this illustrative example, the DPS  100  may include communications bus  102 , which may provide communications between a processor unit  104 , a memory  106 , persistent storage  108 , a communications unit  110 , an Input/Output (I/O) unit  112 , and a display  114 . 
     The processor unit  104  serves to execute instructions for software that may be loaded into the memory  106 . The processor unit  104  may be a number of processors, a multi-core processor, or some other type of processor, depending on the particular implementation. A number, as used herein with reference to an item, means one or more items. Further, the processor unit  104  may be implemented using a number of heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. As another illustrative example, the processor unit  104  may be a symmetric multi-processor system containing multiple processors of the same type. 
     The memory  106  and persistent storage  108  are examples of storage devices  116 . A storage device may be any piece of hardware that is capable of storing information, such as, for example without limitation, data, program code in functional form, and/or other suitable information either on a temporary basis and/or a permanent basis. The memory  106 , in these examples, may be, for example, a random access memory or any other suitable volatile or non-volatile storage device. The persistent storage  108  may take various forms depending on the particular implementation. 
     For example, the persistent storage  108  may contain one or more components or devices. For example, the persistent storage  108  may be a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. The media used by the persistent storage  108  also may be removable. For example, a removable hard drive may be used for the persistent storage  108 . 
     The communications unit  110  in these examples may provide for communications with other DPSs or devices. In these examples, the communications unit  110  is a network interface card. The communications unit  110  may provide communications through the use of either or both physical and wireless communications links. 
     The input/output unit  112  may allow for input and output of data with other devices that may be connected to the DPS  100 . For example, the input/output unit  112  may provide a connection for user input through a keyboard, a mouse, and/or some other suitable input device. Further, the input/output unit  112  may send output to a printer. The display  114  may provide a mechanism to display information to a user. 
     Instructions for the operating system, applications and/or programs may be located in the storage devices  116 , which are in communication with the processor unit  104  through the communications bus  102 . In these illustrative examples, the instructions are in a functional form on the persistent storage  108 . These instructions may be loaded into the memory  106  for execution by the processor unit  104 . The processes of the different embodiments may be performed by the processor unit  104  using computer implemented instructions, which may be located in a memory, such as the memory  106 . 
     These instructions are referred to as program code, computer usable program code, or computer readable program code that may be read and executed by a processor in the processor unit  104 . The program code in the different embodiments may be embodied on different physical or tangible computer readable media, such as the memory  106  or the persistent storage  108 . 
     The program code  118  may be located in a functional form on the computer readable media  120  that is selectively removable and may be loaded onto or transferred to the DPS  100  for execution by the processor unit  104 . The program code  118  and computer readable media  120  may form a computer program product  122  in these examples. In one example, the computer readable media  120  may be computer readable storage media  124  or computer readable signal media  126 . Computer readable storage media  124  may include, for example, an optical or magnetic disk that is inserted or placed into a drive or other device that is part of the persistent storage  108  for transfer onto a storage device, such as a hard drive, that is part of the persistent storage  108 . The computer readable storage media  124  also may take the form of a persistent storage, such as a hard drive, a thumb drive, or a flash memory, that is connected to the DPS  100 . In some instances, the computer readable storage media  124  may not be removable from the DPS  100 . 
     Alternatively, the program code  118  may be transferred to the DPS  100  using the computer readable signal media  126 . The computer readable signal media  126  may be, for example, a propagated data signal containing the program code  118 . For example, the computer readable signal media  126  may be an electromagnetic signal, an optical signal, and/or any other suitable type of signal. These signals may be transmitted over communications links, such as wireless communications links, optical fiber cable, coaxial cable, a wire, and/or any other suitable type of communications link. In other words, the communications link and/or the connection may be physical or wireless in the illustrative examples. 
     In some illustrative embodiments, the program code  118  may be downloaded over a network to the persistent storage  108  from another device or DPS through the computer readable signal media  126  for use within the DPS  100 . For instance, program code stored in a computer readable storage medium in a server DPS may be downloaded over a network from the server to the DPS  100 . The DPS providing the program code  118  may be a server computer, a client computer, or some other device capable of storing and transmitting the program code  118 . 
     The different components illustrated for the DPS  100  are not meant to provide architectural limitations to the manner in which different embodiments may be implemented. The different illustrative embodiments may be implemented in a DPS including components in addition to or in place of those illustrated for the DPS  100 . Other components shown in  FIG.  1     
     Modern database systems can contain relatively large amounts of data. This data can be processed, updated, retrieved, and/or otherwise used for many purposes. Queries can be used to process the data. Queries are generally written to conform to the structure of a database. A single query can retrieve data from multiple data sources, which can result in a variety of potential flow paths to execute the query. One or more indices can be used to reduce the time/computational cost to fully execute the queries. 
     An index is a data structure configured to improve the speed/efficiency of database operations. They can be used to quickly locate data without having to search the entire table. An index can include one or more keys (or primary keys) that indicate the location of the relevant data. The keys can act as a pointer to a location/range where the relevant data is located. Generally, an index is generated for a single table. There is one column/data point that is used to organize/index the data in the relevant table. As such, if two tables are needed, two separate indices can be created/utilized. 
     Embodiments of the present disclosure include a query manager that can build and utilize a hybrid index, (or composite index, or cross table index). A hybrid table can increase the overall efficiency of a database system. The benefit can be based on effectively reducing/eliminating the cost of join or other similar operations that would require the searching of two or more tables/indices. Said differently, the hybrid index can reduce the number of table accesses and/or the number of indices to open/read to fully execute a query. In some embodiments, the hybrid index can use less memory than have two or more separate indices. This can also increase the overall efficiency of the database system. 
     A hybrid index can be an index for two or more tables. The hybrid index can be created/generated based on connections between columns from various tables in a database. 
     Embodiments of the present disclosure include a query manager. The query manager can generate a hybrid index. In some embodiments, the hybrid index is created for two or more tables. In some embodiments, the two or more tables have a column in common and/or a link/relationship between columns from two different tables. The link can be a primary key or a foreign key. A primary key is a column or a set of columns in a table whose values uniquely identify a row in the table. A foreign key is a column or a set of columns in a table whose values correspond to the values of the primary key in a different table. In some embodiments, the link is parent child relationship between the tables. The parent child relationship is the establishment of hierarchal dependencies between two or more columns. In some embodiments the highest/first table in a hierarchy can be the base/basing table. In some embodiments, the hybrid index can be a two-way index. A two-way index can allow for identification of the relevant rows in any of the tables included in the hybrid index. 
     In some embodiments, the hybrid index can include a root page, one or more non-leaf pages, and one or more leaf pages. There can be any number of non-leaf page layers. The non-leaf page will store the foreign keys for the relevant columns. Each leaf page can store the keys (or foreign keys) with the column values and/or the corresponding row identifiers (ID&#39;s) in each basing table. In some embodiments, the hybrid index can allow for any of the tables included in the index to be the base table. 
     In some embodiments, the query manager can receive a query. The hybrid index can be generated before or after the query is received. The query manager can generate and optimize an access path. In some embodiments, the access path utilized the hybrid index. In some embodiments, the query is a cross table query. A cross table query has predicates/actions that require two or more tables in the database. In some embodiments, the query includes a cross table select. The cross table select can be an index only access using the hybrid index. The index only access cuts out the join functions and thereby reduces the overall cost of executing the query. In some embodiments, the query includes an insert into the parent and/or child tables. To execute, the query manager can open the hybrid index, insert the record into the table, then insert the key into the hybrid index. Only a single index is needed to be open. If each table had an index, both indices would be opened and updated. Thus, the hybrid index reduces the time and computational resources to perform the same operations. In some embodiments, the query includes a delete from the parent and/or child table of the hybrid index. The query manager can open the hybrid index, use the index to identify the location in the table, and then delete the records. Again, only a single index is opened, thereby increasing the efficiency of the database system. 
     In some embodiments, the hybrid index can be stored, at least when in use, in a cache block. This can allow for faster processing and effective use of the hybrid index. In some embodiments, the hybrid index can be disabled. The disabling can be based on a ratio of read/writes exceeding a threshold. When the threshold is exceeded, the index can be disabled and asynchronously updated during idle time. 
     The aforementioned advantages are example advantages, and embodiments exist that can contain all, some, or none of the aforementioned advantages while remaining within the spirit and scope of the present disclosure. 
     Referring now to various embodiments of the disclosure in more detail,  FIG.  4    is a representation of a computing environment  400  that is capable of running a query manager in accordance with one or more embodiments of the present disclosure. Many modifications to the depicted environment may be made by those skilled in the art without departing from the scope of the disclosure. 
     Computing environment  400  includes host  405 , database  430 , and network  440 . Network  440  can be, for example, a telecommunications network, a local area network (LAN), a wide area network (WAN), such as the Internet, or a combination of the three, and can include wired, wireless, or fiber optic connections. Network  440  may include one or more wired and/or wireless networks that are capable of receiving and transmitting data, voice, and/or video signals, including multimedia signals that include voice, data, and video information. In general, network  440  may be any combination of connections and protocols that will support communications between and among host  405 , database  430 , and other computing devices (not shown) within computing environment  400 . In some embodiments, each of host  405  and database  430  may include a computer system, such as the data processing system  100  of  FIG.  3   . 
     Host  405  can be a standalone computing device, a management server, a web server, a mobile computing device, or any other electronic device or computing system capable of receiving, sending, and processing data. In some embodiments, host  405  can represent a server computing system utilizing multiple computers as a server system, such as in a cloud computing environment  50  (shown in  FIG.  1   ). In some embodiments, host  405  represents a computing system utilizing clustered computers and components (e.g., database server computers, application server computers, etc.) that act as a single pool of seamless resources when accessed within computing environment  400 . In some embodiments, host  405  includes database manager  410  and application  412 . 
     Database manager  410  can be any combination of hardware and/or software configured to manage database operations. The operations may include storing, retrieving, querying, manipulating, monitoring, and analyzing data along with other similar operations. In some embodiments, database manager  410  includes a database management system (DBMS). In some embodiments, database manager  410  is part of a federated database system (which can include database  430 ). A federated database system can transparently map multiple autonomous database systems into a single federated (combined) database. In some embodiments, a federated database system acts as a virtual database, where there is no actual data integration in the constituent databases. 
     Application  412  can be any combination of hardware and/or software that is configured to generate a query. A query can be a request for data and/or information stored in one or more tables of one or more databases. The databases may be local (e.g., on host  405 ), or remote (e.g., database  430 ). In some embodiments, application  412  sends the query to database manager  410 , database  430 , and/or query manager  431 . In some embodiments, the queries generated by application  412  can be sent as a batch to database manager  410  and/or database  430 . In some embodiments, the queries can be sent on an as need basis and/or continuously. In some embodiments, application  412  is included in database manager  410  or vice versa. In some embodiments, application  412  can generate/send two or more different queries. In some embodiments, the query is generated in SQL. In some embodiments, application  412  displays the results of the query. The results may be returned in an SQL format, and/or as images, graphs, trends, and/or other similar formats. 
     In some embodiments, application  412  is part of a computing device separate from host  405 . The computing device may communicate with host  405  via network  440 . In some embodiments, the computing device can generate queries, send queries to host  405 , and/or receive and display the results of the query. In some embodiments, application  412  can include (or be considered) two or more separate applications, wherein each application is configured to generate and send queries to database  430 . 
     In some embodiments, host  405  includes one or more applications consistent with application  412 . Or said differently, application  412  can include any number of unique applications. In some embodiments, computing environment  400  includes one or more additional computing devices that include an application consistent with application  412 . In some embodiments, each application can generate the same and/or different queries than application  412 . 
     Database  430  can be any combination of hardware and/or software configured to store data in a database system. In some embodiments, database  430  is part of a federated database system. A federated database system can be any number databases that appear as a single database to the requesting device (e.g., host  405 , application  412 , etc.). In some embodiments, database  430  includes two or more databases communicatively connected that can act as a single database (e.g., a federated database system). In some embodiments, database  430  may be contained within host  405 . In some embodiments, database  430  can include query manager  431 , SQL parser  432 , table  433  ( 1 ), table  433  ( 2 ), table  433  ( n ), and hybrid index  434 . Table  433 ( 1 ), table  433 ( 2 ), and table  433  ( n ) can represent any number of tables and will be referred to as table  433  collectively, individually, and/or severally. 
     Query manager  431  can be any combination of hardware and/or software configured to oversee execution of an SQL query. In some embodiments, query manager  431  includes one or more of SQL parser  432 , table  433 , and hybrid index  434 . However,  FIG.  4    depicts them as separate components for discussion purposes. In some embodiments, query manager  431  can generate and/or utilize hybrid index  434 . In some embodiments, query manager  431  can return results of the query to the source (e.g., host  405 ). In some embodiments, the queries are multi-table queries. A multi-table query is any query that includes two or more tables in database  430 . 
     The SQL parser  432  can be any combination of hardware and/or software configured to determine actions to be performed from a query. In some embodiments, SQL parser  432  determines individual commands to fully execute the query (e.g., return a set of data). In some embodiments, SQL parser  432  develops an access path for the queries. The access path indicates an order in which to perform the various commands included in a query. In some embodiments, two or more access paths can accomplish the results of the query. SQL parser  432  can optimize the query. The optimizing can include selecting the access path that will result in the lowest cost to fully execute the query. In some embodiments, SQL parser  432  can determine if user of hybrid index  434  is included in the lowest cost access path. 
     Table  433  can be any data structure configured to store and organize data. In some embodiments, each table can include one or more columns and rows. In some embodiments, any or each table  433  can be linked to at least one other table in database  430 . The link can be based on a common data column, a designated relationship (e.g., defined link between tables), a dependency relationship (e.g., a column in table A is used to calculate a column in table B), and the like. In some embodiments, each table includes one or more non-ordering columns. A non-ordering column can hold any type of data. The non-ordering column will be associated with (e.g., on the same row) an ordering column (or a primary key column). 
     Hybrid index  434  can be a data structure configured to act as an index for two or more tables. In some embodiments, hybrid index  434  is generated for two or more tables. In some embodiments, there can be two or more separate indexes within database  430 . Hybrid index  434  can include data for two or more of table  433 . In some embodiments, hybrid index  434  can include at least one ordering row and one non-ordering row from each of the two or more tables. The ordering row (or, identifying column, key column, primary key column, etc.) can be the link between the two or more tables. The non-ordering row can be the columns of data associated with the ordering row. 
     In some embodiments, the contents of hybrid index  434  are based on one or more received queries. For example, if one query request Table A column  1  and Table B column  3 , then the hybrid index can include the referenced columns. In some embodiments, the hybrid index  434  is based on columns/tables that are frequently referenced in various queries. For example, if 75% of queries use a column called “customer ID” and 60% use a column called “Email”, in a different table, then hybrid index  434  can be generated for those two columns/tables. In some embodiments, the contents of hybrid index  434  includes all common columns between tables. For example, if three separate tables can have a “Customer ID” column, then those three tables can be used to build hybrid index  434 . In some embodiments, hybrid index  434  includes a row ID (“RID”) column for each table in the index. Any number of additional columns from each table can be included in hybrid index  434 . 
       FIG.  5    includes an embodiment of a hybrid index structure.  FIG.  5    includes root page  510 , non-leaf page  520 , non-leaf page  521 , non-leaf page  522 , leaf page  530 , leaf page  531 , leaf page  532 , leaf page  533 , and leaf page  534 . Various embodiments can have different number of layers, non-leaf pages, and leaf pages. 
     Root page  510  can include a page pointer and a primary key. Root page  510  can include one or more primary keys that refer to one or more non-leaf pages. The key in root page  510  can point to a primary table and/or a child table. Each non-leaf page can include a different primary key. The number of keys, and the number of sub-layers that are referenced can be based on the amount of data that is held in the index. Each leaf page can include more than one key. The leaf page can include an index key, and a key for each included column (e.g., a column key). In some embodiments, a foreign key is one that points to the specific column of data. 
       FIG.  6    includes an example instruction to create a hybrid table and column structure of a hybrid index.  FIG.  6    includes command  610 , and index  620 . Command  610  includes the instruction to create an index of “index-name” with three tables. There is the parent table “main_tb” and two child tables “foreign_tb1” and “foreign_tb2”. For each table, the instruction includes a key column that links the three tables. This could be a customer ID, as an example. The instruction also includes which columns to include from each table, identified as “column-name_A”, “column-name_B”, and “column-name_C”. There can be additional columns added from each table as needed. Index  620  has eight columns. In some embodiments, index  620  includes a flag column. The flag column can be a header for the hybrid index. One or more leaf pages can point to the flag column. The primary key column is the link between the primary table and the two child tables. The primary key can also be an identified column. There is a column for each included column from each table. This embodiment has three columns, one from each table, “column-name_A”, “column-name_B”, and “column-name_C”. The remaining columns are RID columns for each table. There will always be one RID column for each table included in hybrid index  434 . There can be more than one column included. One hybrid index will use less storage/memory than three separate indices for each table. 
       FIG.  7    depicts a flowchart of an example method  700 , for generating and utilizing a hybrid index that can be performed in a computing environment (e.g., computing environment  400  and/or cloud computing environment  50 ). One or more of the advantages and improvements described above for generating and utilizing hybrid index may be realized by method  700 , consistent with various embodiments of the present disclosure. 
     Method  700  can be implemented by one or more processors, host  415 , database manager  410 , application  412 , database  430 , query manager  431 , SQL parser  432 , table  433 , hybrid index  434  and/or a different combination of hardware and/or software. In various embodiments, the various operations of method  700  are performed by one or more of host  415 , database manager  410 , application  412 , database  430 , query manager  431 , SQL parser  432 , table  433 , and hybrid index  434 . For illustrative purposes, the method  700  will be described as being performed by query manager  431 . 
     At operation  702 , query manager  431  receives a query. In some embodiments, the query is received from application  412 , database manager  410 , and/or host  405 . In some embodiments, the query is received in Standard Query Language (SQL). In some embodiments, the query is configured to perform one or more commands on a set of data stored in database  430 . In some embodiments, the received query is configured to perform operations in two or more of tables  433 . The query can include one or more of a select command, a delete command, an insert command, and an update command. In some embodiments, operation  702  includes generating a query access path. The query access path can represent the order of operations to properly execute the query. The query access path can be optimized by an optimizer. The optimizer can generate multiple paths to process the query and predict which of the multiple paths has the lowest cost. 
     At operation  704 , query manager  431  generates a hybrid index. (e.g., hybrid index  434 ). In various embodiments, the order of operation  704  and  702  can be switched. In some embodiments, hybrid index  434  can be used for multiple queries. In some embodiments, the query can include an instruction to generate hybrid index  434  (e.g., see  FIG.  6   ). In some embodiments, the structure and format of the hybrid index are consistent with  FIGS.  5  and  6   . 
     In some embodiments, the hybrid index in maintained in a cache block. The cache block can be a portion of relatively high speed memory compared to long term storage. This can allow for high concurrency of transactions and make the index more useful to the database system. 
     At operation  706 , query manager  431  executes the query. In some embodiments, the hybrid index is used to execute the query. This can greatly reduce the cost needed to execute the query. In particular, the hybrid index can eliminate the need to perform a join command. Join commands are generally computationally expensive. The query can be executed based on the query access path. As new queries are generated and/or as software is updated the hybrid index can be updated (or a new hybrid index generated) to better process new/updated queries. In some embodiments, operation  706  includes returning the query to the source. Returning can include sending a data set and/or a confirmation that the actions of the query were completed. 
     In some embodiments, the query includes an insert command. To execute the insert command, query manager  431  can open the hybrid index, find the parent key in the index, insert the record into the database, and then insert the key for the new record into the index. In this way, the method only requires opening one index instead of two like traditional indexing methods. 
     In some embodiments, the query includes a delete command. To execute the delete command, query manager  431  opens the hybrid index, uses the index key to identify the location of the records and then deletes the records in all tables as instructed by the query. A similar benefit for delete commands exists as for insert commands. Only one index is opened, and it can reduce I/O while searching for the appropriate rows/keys to process the query. 
     In some embodiments, the query includes a select command. To execute the select command, query manager  431  can open the index, use the query to find the relevant keys from the index, pull the data from the index, then output the result. There is no need to access either table and/or perform any join operation. This can result in a significant computing cost saving. 
     In some embodiments, the hybrid index can be disabled during query execution. In some embodiments, the disabling is based on the read/write ratio (or vice versa). Said differently, the disabling can be based on the number of insert/update/select commands compared against each other. As the ratio of writes increases compared to reads, it is more likely the index will become outdated. The index can be disabled. In some embodiments, the hybrid index is asynchronously updated during idle time, and re-enabled once the updates are complete and/or the ratio returns below the threshold. 
     Computer Technology and Computer Readable Media 
     The present invention may be a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.