Patent Publication Number: US-2020293512-A1

Title: Data compartments for read/write activity in a standby database

Description:
This application is a continuation application claiming priority to Ser. No. 15/461,688, filed Mar. 17, 2017. 
    
    
     TECHNICAL FIELD 
     The present invention relates to systems and method for providing an active read-writable standby database while preserving data consistency with a primary database, and more specifically to embodiments of data compartment for read/write activity in a standby database. 
     BACKGROUND 
     Current standby databases are used to support read/write activity performed on primary databases, and are designed for read-only activity for disaster recovery purposes. 
     SUMMARY 
     An aspect of this invention relates to a method, and associated computer system and computer program product, for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database. A processor of a computing system syncs the primary database with a physical standby mirror existing on the standby database, wherein a first data object and a second data object written to the primary database from a live application is synced in a read only access on the physical standby mirror. A first data compartment and a second data compartment are created on the standby database, separate from the physical standby mirror. A change made to the first data object on the primary database is applied to the corresponding first data object on the physical standby mirror. The processor determines that (i) the change should be applied to the corresponding first data object stored on the first data compartment in accordance with data merge rules associated with the first data compartment to keep the data stored on the first data compartment updated in real-time and in sync with the physical standby mirror, and (ii) the change should not be applied to the corresponding first data object stored on the second data compartment in accordance with data merge rules associated with the second data compartment. 
     The foregoing and other features of construction and operation will be more readily understood and fully appreciated from the following detailed disclosure, taken in conjunction with accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a block diagram of an active read-writable standby database server system, in accordance with embodiments of the present invention. 
         FIG. 2  depicts a more detailed block diagram of the active read-writable standby database server system of  FIG. 1 , in accordance with embodiment of the present invention. 
         FIG. 3  depicts a block diagram of the active read-writable standby database server system during a cloning process, in accordance with embodiments of the present invention. 
         FIG. 4  depicts a flowchart of a method for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database, in accordance with embodiments of the present invention. 
         FIG. 5  depicts a flowchart of a step of the method of  FIG. 4 , in accordance with embodiments of the present invention. 
         FIG. 6  depicts a flowchart of a cloning method using the active read-writable standby database server system of  FIG. 3 , in accordance with embodiments of the present invention. 
         FIG. 7  depicts a block diagram of a computer system for the active read-writable standby database server system of  FIG. 1 , capable of implementing methods for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database of  FIGS. 4-6 , in accordance with embodiments of the present invention. 
         FIG. 8  depicts a cloud computing environment, in accordance with embodiments of the present invention. 
         FIG. 9  depicts abstraction model layers, in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Current state of art pertaining to standby databases supports read-write activity to be performed on primary databases with read-only activity being allowed on standby databases. Read-write activity is not currently supported on standby databases due to the technical and design challenges of implementing such a solution. Standby databases may be ideal candidates to be used as reporting databases to offload reporting from the primary instances. Most off-the-shelf reporting tools, such as Microstrategy®, etc. need read-write access to the database to create temporary, staging tables to perform aggregations and sorting at the database layer before presenting the results to the end user layer. In addition, building pre-production databases from production data from databases growing to the order of hundreds of terabytes can be challenging. Current standby databases employing a read-only activity cannot: (a) build pre-production databases from production data; (b) perform incremental application tests on the pre-production data which change the table structures and/or the data; (c) continue to receive incremental updates while the pre-production data is being refreshed incrementally from production data, and (d) perform real-time switching back and forth from multiple versions of production and pre-production data. Further, the above-identified limitations render most off-the-shelf reporting tools practically useless in conventional standby database environments. Thus, a need exists for standby databases that can used for read-write activity simultaneously with the primary database. 
     Embodiments of the present invention relates to a system and method for delivering standby databases as compartmental instances that are available for read and write activity, thus enabling reporting tools, analytical tools, and application test cycles to run against real-time ‘live’ production data on the standby databases. Moreover, embodiments of the system and method of the present invention provides methods to drastically eliminate turnaround times associated with refreshing pre-production and test databases with production data in real-time. 
     Embodiments of the system and method may allow standby database instances (e.g. via compartments) to be opened in read-write mode in addition to maintaining the data consistency with the primary database(s), which may allow a standby database to work seamlessly with off-the-shelf reporting tools, as well as perform data warehousing aggregations and cube creations on the standby databases while still retaining the data consistency with the primary database. Embodiments of the standby database of the present system may meet the standby database&#39;s real point objective (RPO) and real time objective (RTO) objectives for disaster recovery purposes, but may also ensure that the disaster recovery capacity is being used while taking full advantage of the fact that the data is closely in sync (e.g. as close as real-time) with the primary database. Additionally, embodiments of the standby database server can also provide multiple compartments of data where different reporting or predictive, modelling, and/or data warehousing applications can run against the a compartment&#39;s data while still being kept up to date with the latest production data changes. 
     A few advantages provided by embodiments of the present invention include an ability to quickly clone multiple instances from an existing compartment or the main physical standby mirror (PSM) instance, which may allow for real-time setup of instances for reporting and application testing purposes. Reporting applications can run on real-time data without expending resources on the ‘Active’ instance which is used for production operational purposes, which may allow off-the-shelf reporting applications to create temporary database objects in the compartmental instances on the standby database server while using real time “live” data for building reports. Application testing cycles can be repeated as often and as frequently as required because reading data blocks from the standby database can be done instantaneously by cloning/refreshing a compartment from the main PSM or a static PSM, in addition to a cloned compartment of the standby database. The ability to build/clone instantaneous compartments on request using a ‘Fast Clone Refresh’ mechanism, as described in greater detail infra. A mirror image of a standby PSM instance in addition to multiple “divergent” compartmental instances may be simultaneously maintained. Further, failover from production to standby is close to instantaneous because of the “static” mirrored compartments that can co-exist with divergent compartments. 
     Referring to the drawings.  FIG. 1  depicts a block diagram of an active read-writable standby database server system  100 , in accordance with embodiments of the present invention. Embodiments of an active read-writable standby database server system  100  may be described as a standby database server system that allows for read-write activity on portions of the standby database server, while also providing a satisfactory backup for the primary database. 
     Embodiments of the active read-writable standby database server system  100  may include a primary database  110 . Embodiments of the primary database  110  may be one or more databases associated with live application  111  for storing data objects. The primary database  110  may include read-write activity, such that users using a live application  111  may directly save to the primary database, which may store data associated with one or more live applications  111 . Embodiments of a live application  111  may be a software application running on one or more computing devices, wherein application data from the live application  110  is stored on the primary database  110 . Embodiments of the live application  110  may be associated with banking transactions, logistic applications, store applications, shopping applications, and the like, being used by users, such as customers, employees, and the like. For example, if the live application  110  is associated with a retailer, the primary database  110  may include data for store inventory, and when an item is sold, the primary database  110  may be updated to reflect the change (i.e. read-write capability). As in most cases, the primary database  110  holds critical information, and is constantly being updated. Due to the criticality of the information contained on the primary database  110 , a conventional standby database is used as a backup to the primary database, but is afforded only read-only access. Further, reporting applications  113 , which may be a software application running on one or more computing device, are used for creating data spreadsheets, tables, indexes, and the like, for data analytics. Typically, the reporting applications  113  create new data objects on the primary database  110  while preparing pre-production and production data for reports, which further consume processing resources of the primary database  110 . 
     Moreover, embodiments of the primary database  110  and the applications  111 ,  112 ,  113  may be coupled to a computing system  120  over a network  107 . In an alternative embodiment, the primary database  110  may be connected to computing system  120  via a data bus line. A network  107  may refer to a group of two or more computer systems linked together. Network  107  may be any type of computer network known by individuals skilled in the art. Examples of computer networks  107  may include a LAN, WAN, campus area networks (CAN), home area networks (HAN), metropolitan area networks (MAN), an enterprise network, cloud computing network (either physical or virtual) e.g. the Internet, a cellular communication network such as GSM or CDMA network or a mobile communications data network. The architecture of the computer network  107  may be a peer-to-peer network in some embodiments, wherein in other embodiments, the network  107  may be organized as a client/server architecture. 
     In some embodiments, the network  107  may further comprise, in addition to the computer system  120 , primary database  110 , and applications  111 ,  112 ,  113 , a connection to one or more network accessible knowledge bases containing information of one or more users, network repositories  114  or other systems connected to the network  107  that may be considered nodes of the network  107 . In some embodiments, where the computing system  120  or network repositories  114  allocate resources to be used by the other nodes of the network  107 , the computer system  120  and network repository  114  may be referred to as servers. 
     The network repository  114  may be a data collection area on the network  107  which may back up and save all the data transmitted back and forth between the nodes of the network  107 . For example, the network repository  114  may be a data center saving and cataloging data sent by or received from the primary database  110  or applications  111 ,  112 ,  113  to generate both historical and predictive reports regarding a performance or capacity of computing system  120 . In some embodiments, a data collection center housing the network repository  114  may include an analytic module capable of analyzing each piece of data being stored by the network repository  114 . Further, the computer system  120  may be integrated with or as a part of the data collection center housing the network repository  114 . In some alternative embodiments, the network repository  114  may be a local repository (not shown) that is connected to the computer system  120 . 
     Referring still to  FIG. 1 , embodiments of the computing system  120  may be one or more servers. Embodiments of the computing system  120  may include a standby database  130 . Embodiments of the standby database system  130  may be one or more databases, and may include a synchronization module  131 , a compartment module  132 , a rules module  133 , and a clone module  134 . A “module” may refer to a hardware based module, software based module or a module may be a combination of hardware and software. Embodiments of hardware based modules may include self-contained components such as chipsets, specialized circuitry and one or more memory devices, while a software-based module may be part of a program code or linked to the program code containing specific programmed instructions, which may be loaded in the memory device  142  of the computer system  120 , which may be coupled to the standby database system  130 . A module (whether hardware, software, or a combination thereof) may be designed to implement or execute one or more particular functions or routines. 
       FIG. 2  depicts a more detailed block diagram of the active read-writable standby database server system  100  of  FIG. 1 , in accordance with embodiment of the present invention. Embodiments of the computing system  120 , as depicted in  FIG. 2 , may include the standby database system  130 , which includes a physical standby mirror (PSM)  160 . Embodiments of the synchronization module  131  of the standby database system  130  may include one or more components of hardware and/or software program code for syncing the primary database  110  with the PSM existing on the standby database. For instance, a first data object  115  and a second data object  116  may be written to the primary database  110  from a live application  111 . In response to the first data object  115  and the second data object  116  being written to the primary database  110 , the synchronization module  131  may sync or receive instructions to sync the first data object  115  and the second data object  116  in a read-only access on the PSM. Embodiments of the PSM  160  may exist on the standby database or a disaster recovery site, wherein the PSM  160  may be constructed and maintained with a block level consistency with the primary database  110 . In an exemplary embodiment, the PSM  160  is not available for write usage. Moreover, embodiments of the synchronization module  131  may ensure that the data objects written to the primary database  110  are backed up and written in a read-only fashion to the PSM  160 . Embodiments of the PSM  160  may then still allow the standby database system  130  to function as a disaster recovery database, meeting desired RPO and RTO. 
     If a change is made to the first data object  115  and/or the second data object  116 , the synchronization module  131  may propagate the change to the corresponding data objects  115 ,  116  stored on the PSM  160 , so that the data objects, even when changed, are in sync with the primary database  110  in a read-only access. For example, a transaction log stream  157 , or redo stream, may capture, monitor, manage, etc. any changes made to the data objects  115 ,  116  on the primary database  110 , by for example an end user using a live application  111 . The PSM  160  may cooperate with the transaction log stream  157  to propagate the changes contained in the transaction log stream  157 . Accordingly, the data objects of the PSM  160  mirror, in a real-time manner, the data objects present on the primary database  110 . 
     Referring still to  FIGS. 1-2 , embodiments of the standby database system  130  of the computing system  120  may include a plurality of data compartments  171 ,  172 ,  173 . The plurality of data compartments  171 ,  172 ,  173  may be created, initialized, utilized, and/or generated with read-write capability, separate from the PSM  160 . Embodiments of the PSM  160  and the data compartments  171 ,  172 ,  173  may be located on the same server, or may be located on different servers, wherein the one or more servers including the PSM  160  and the data compartments  171 ,  172 ,  173  may form the computing system  120 . Embodiments of the standby database system  130  may include a compartment module  132 . Embodiments of the compartment module  132  of the standby database system  130  may include one or more components of hardware and/or software program code for utilizing, establishing, creating, initializing, and/or generating a first data compartment  171  and a second data compartment  172  or additional data compartments, such as data compartment  173  on the standby database, separate from the physical standby mirror  160 . Embodiments of the data compartments  171 ,  172 ,  173  may be versioned compartments which are branched offshoots from the PSM  160 . Embodiments of the compartment module  132  may create and/or generate any number of data compartments required by the system  100 , and may be limited only to the scalability of the infrastructure, wherein an infrastructure housing the data compartments  171 ,  172 ,  173  can be either horizontally or vertically scalable. Moreover, embodiments of the data compartments  171 ,  172 ,  173  may have a read-write access/function such that other operations, such as reporting or testing functions, may be accomplished by accessing the plurality of data compartments  171 ,  172 ,  173 , which saves processing power and resource bandwidth normally required of the primary database  110 . 
     Furthermore, the data compartments  171 ,  172 ,  173  may include data objects from the PSM  160 . For instance, the first data object  115  and the second data object  116  may be present on the first data compartment  171 , the second data compartment  172 , and a third data compartment  173 , in a read-write accessibility. Embodiments of the compartment module  132  may communicate with a compartment manager  170  that may manage the data compartments  171 ,  172 ,  172  by keeping track of the number of data compartments utilized, as well as data objects stored thereon. 
     Embodiments of the standby database system  130  of computing system  120  may further include a rules module  133 . Embodiments of the rules module  133  of the standby database system  130  may include one or more components of hardware and/or software program code for determining whether changes made to the first data object  115  and/or the second data object  116  on the primary database  110  should be applied, propagated, etc. to the data objects  115 ,  116  on the data compartments  171 ,  172 ,  173 . As noted above, if a change is made to the data objects  115 ,  116  on the primary database by a user interfacing with live application  110 , the change is captured by the transaction log stream  157  and ultimately the change is applied to the data objects  115 ,  116  on the PSM  160 . However, embodiments of the rules module  133  may determine whether the changes to the data objects  115 ,  116  applied on the PSM  160  should be further applied to the data objects  115 ,  116  stored on the data compartments  171 ,  172 ,  173 . In some cases, the change is applied to one of the data compartments  171  such that the data compartment  171  is kept in sync with the PSM  160 . If the data compartment is kept in sync with the PSM  160 , the data compartment  171  may be referred to as a static compartment. Embodiments of the static compartments may be created as read only compartments that are in sync with the PSM  160 . If the data compartment, such as data compartment  172 , is not to be kept in sync with the PSM  160 , the data compartment  172  may be referred to as a divergent compartment. Embodiments of the divergent compartment may be data compartments available for read-write, and have data that has diverged from the PSM  160  over a period of time. 
     Embodiments of the rules module  133  may communicate with a data merge engine  165 , which may include/provide data merge rules and/or logic regarding an operation of the data compartment. For instance, the rules module  133  in cooperation with the data merge engine  165  may determine whether a data compartment  171 ,  172 ,  173  is static or divergent. The determination by the rules module  133  by consulting the data merge rules generated by the data merge engine  165  may allow a determination, for each data compartment, of whether a change to the data objects  115 ,  116  on the PSM  160  should be applied to the data objects  115 ,  116  located on the data compartments  115 ,  116 . 
     In addition to, or as an alternative to a yes/no determination of whether the data compartments  171 ,  172 ,  173  should ever be updated with changes made to the data objects of the PSM  160 , the rules module  133  may further determine that some changes to the PSM  160  should be applied to a particular data compartment, while that same change should not be applied to another data compartments, in accordance with data merge rules associated with each data compartment  171 ,  172 ,  173 . Similarly, some data compartments  171 ,  172 ,  173  may include read-write access, and apply some changes made to the PSM  160 , but not necessarily all of the changes to the PSM  160 . The determination may be made in accordance with the data merge rules associated with each data compartment by analyzing a redo/change stream associated with each data compartment  171 ,  172 ,  173 . For instance, the data merge rules of the data merge engine  165  may provide that some data objects on the first data compartment  171  should be kept in sync with the PSM  160 , while other data objects should not. Each data compartment  171 ,  172 ,  173  has data merge rules that specify where and which objects, tablespaces, schemas, etc. can be excluded/included from being synchronized with the PSM  160 . For every redo change applied in the PSM  160 , the data merge engine  165  may filter out one or more exclusions from a main redo stream, which may produce a customized redo stream to each data compartment  171 ,  172 ,  173 . In an exemplary embodiment, internally within each data compartment  171 ,  172 ,  173 , the redo stream may be dequeued in sequential order, and object identifiers remapped. For example, one stream of redo changes from the PSM  160  which pertains to read-only objects is applied at the block level to the target compartment, which may be a static data compartment, while a second stream of redo changes pertaining to the excluded objects applied by converting the redo stream into logical SQL statements, may be applied at the block level to a target data compartment, depending on the data merge rules specified for the particular data compartment. Further, each data compartment  171 ,  172 ,  173  may generate a stream of redo/changes, wherein the data compartment  171 ,  172 ,  173  can be completely recovered to any point in time using the data compartment&#39;s redo stream. 
     Accordingly, the active read-writable standby database server system  100  may provide flexibility over current read only standby database solutions. The system  100  may include a plurality of data compartments, wherein some data compartments may be completely static (i.e. in sync with the PSM  160  and read only) and other data compartments may be divergent data compartments, with data merge rules specific to each data compartment  171 ,  172 ,  173  (i.e. read-write data compartments that may or may not apply a change made to the PSM from the redo stream based on associated data merge rules. 
     With continued reference to  FIG. 2 , embodiments of the computing system  120  having standby database system  130  may allow for a reporting application  113  to create a new data object  117  on a read-write data compartment, such as data compartment  171 . Most off-the-shelf reporting tools require the need to create a new data object (e.g. data table, index, etc.) to prepare a data production report for an end user. In an exemplary embodiment, the reporting application  113  may access the first data compartment  171 , or any read-write data compartment, and write to the data compartment for purposes of preparing a report for an end user operating the reporting application  113  on the end user&#39;s computing device. Therefore, reporting application(s)  113  may be pointed against such read and write data compartments to have access to real-time and current data along with the ability to create temporary reporting objects, such as new data object  117 . For example, the reporting application  113  may access the first data compartment  171 , which may include a data object  115  that is updated in real-time from the PSM  160  that mirrors the primary database  110 . Data object  115 , and other data objects, may be utilized by the reporting application  113  to create new, temporary data object  117  on the first data compartment, which is a part of the standby database, and not the primary database  110 . Accordingly, the active read-writable standby database server system  100  allows for creation of production data reports to be created using resources of the standby database, thereby offloading work from the primary database  110  to save primary database processing power and resources. Further, a data compartment  171 ,  172 ,  173  can be refreshed any time from the compartment&#39;s parent PSM  160 , while the rest of the data compartments are functioning independently, which may allow refresh operations to complete seamlessly, and for reporting and test applications  112 ,  113  to access the “earlier” image/compartment right up to the time when the new image refresh has taken place. Thus, down time for reporting and testing applications and access to data is drastically reduced. 
     Referring back to  FIG. 1 , embodiments of the standby database system  130  of the computing system  120  may include a clone module  134 . Embodiments of the clone module  134  may include one or more components of hardware and/or software program code for cloning a plurality of data objects to a third data compartment  173 , in response to a request by a testing application  112  to perform a cloning process. Embodiments of the a testing application  112  or test application may be a software application running on a computing device, wherein an end user may utilize the testing application  112  to perform various tasks, such as a test to the system  100 , cloning of one or more portions of the standby database for testing purposes, and the like.  FIG. 3  depicts a block diagram of the active read-writable standby database server system  100  during a cloning process, in accordance with embodiments of the present invention. Testing application  112  may read a target data object from the third data compartment  173  if the target data object has been successfully cloned on the third data compartment  173 , and reads the target data object from the physical standby mirror  160  if the target data object has yet to be successfully cloned to the third data compartment  173 . As an example, testing application  112  may initiate a cloning process such that data stored on the standby database may be cloned to a new clone compartment, such as data compartment  173 . In response to receiving a request to clone data, the clone module  134  may invoke a command to create a new compartment, such as a third data compartment  173 , from the PSM  160 . At different times in the cloning process, some data blocks may have already been cloned to the new clone compartment  173 , such as data block  181 , while the construction of other blocks to clone compartment  173  are still in progress, such as data block  182   b . Data blocks located on the PSM  160  may be depicted as block  182   a . As an example of the cloning process, which may be referred to a fast clone refresh method, testing application  112  may access data compartment  173  to read data block #4. The request to read data block #4 may be received by block manager  177 , which may manage and/or process requests to read data blocks present on the data compartment  173 . The block manager  177  determines that block #4 has already been successfully cloned to the new compartment  173 , and allows the testing application  112  to read data block #4. The testing application  112  may likewise requests to read data block #7 from the clone compartment  173 . The block manager  177  may determine that data block #7 has not yet been cloned to the clone compartment  173 , and may redirect the request to read data block #7 to the PSM  160 , so that the data block #7 can be read by the testing application  112  without waiting for the block #7 to be created on the clone compartment  173 . The redirect may first be made to the compartmentalized cache  176 , which is a memory structure, in an attempt to read data block #7 from cache. If the data block #7 cannot be read from the compartmentalized cache  176 , then the request may be redirected to the PSM  160 , which includes data block #7. 
     Furthermore, the entire cloning process may be instantaneous. While the clone compartments data blocks are being populated, embodiments of the clone module  134  may read the corresponding blocks from the PSM  160 , which allows for application testing to start with almost no turnaround time. If any changes are made to the blocks during the testing and while the new compartment  173  is being built, the new/changed blocks may directly be written into the compartment  173 . If one of the compartments needs to become the “active” instance, the clone module  134  may point the application  112  to the compartment instance. Further, a single PSM  160  can have multiple compartmental instances registered to the PSM  160 . Each PSM  160  may have one main listener which may accept connections to either the main PSM  160  or the inherited compartmental instances. Applications or user sessions connecting to compartments may do so by specifying the host name, port name, PSM (Instance name) as well as the Compartment name. Multiple clone compartments can be created from any of the existing data compartments or from the PSM  160 . 
     Referring still to  FIG. 1 , embodiments of the computer system  120  may be equipped with a memory device  142  which may store information/data, reports, and a processor  141  for implementing the tasks associated with the active read-writable standby database server system  100 . 
     With continued reference to the drawings,  FIG. 4  depicts a flowchart of a method  200  for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database, in accordance with embodiments of the present invention. One embodiment of a method  200  or algorithm that may be implemented for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database in accordance with the active read-writable standby database server system  100  described in  FIGS. 1-3  using one or more computer systems as defined generically in  FIG. 7  below, and more specifically by the specific embodiments of  FIGS. 1-3 . 
     Embodiments of the method  200  for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database may begin at step  201  wherein the PSM  160  is synced with the primary database  110 . Step  202  creates one or more data compartments  171 ,  172 ,  172 , wherein some or all of the data compartments  171 ,  172 ,  173  may include a read-write capability. Step  203  applies a change made to a data object on the primary database  110  to a corresponding data object on the PSM  160 , which may maintain a data consistency with the primary database. The change applied to the PSM  160  to capture the change to the primary database  110  may be done so as a read only access. Step  204  determines whether the change should be applied to the corresponding data objects on the one or more data compartments  171 ,  172 ,  173 . Step  305  applies a block level change to the data object to the data compartments, in accordance with data merge rules associated with the data compartments  171 ,  172 ,  173 . 
       FIG. 5  depicts a flowchart of a step  204 ,  205  of the method of  FIG. 4 , in accordance with embodiments of the present invention. At step  301 , the change stream has been applied to the PSM  160  so that the PSM  160  is current and up-to-date with the primary database  110 . At step  302 , a call is made to the compartment manager  170  to determine whether any data compartments  171 ,  172 ,  173  have been created. Step  303  returns a list of active data compartments  171 ,  172 ,  173 . Step  304  determines whether a target active data compartment included in the list returned by the compartment manager  170  is static or divergent. If the active data compartment is static, step  305  applies the block level change to the data object in the target data compartment. If the target data compartment is divergent, then step  306  collates a list of data objects and schemas, step  307  iterates through the redo/change stream associated with the target data compartment, and step  308  identifies data object from a change vector. Step  309  determines whether the data object is excluding from sync operations, in accordance with the data merge rules associated with the target data compartment. If the object is not excluded from sync operations, then step  310  applies the block level changes to the data object in the target data compartment. If the object is excluded from sync operations, then step  311  decides that the change to the data object of the target compartment will not be applied. 
       FIG. 6  depicts a flowchart of a cloning method  400  using the active read-writable standby database server system  100  of  FIG. 3 , in accordance with embodiments of the present invention. The fast clone fresh method  400  may begin at step  401 , which receives a request for a new compartment to be built for the cloning of data on the PSM  160 , or potentially from another data compartment already active. In response to receiving the request, for example, from a testing application  112 , step  402  may create a new compartment for the cloned data. Step  403  begins cloning the data blocks from the PSM  160  or the other active compartment to the new clone compartment  173 . Step  404  receives a request to read a data block from the clone compartment  173 . For instance, a testing application  112  may, during the cloning process, request to read a particular data block on the clone compartment  173 . Step  405  determines whether the particular data block is successfully clones to the clone compartment  173 . If the particular data block has been cloned and is present on the clone compartment  173 , step  406  reads the data block from the clone compartment  173 . If the particular data block has not been cloned (e.g. construction of data block to clone compartment in progress), step  407  redirects the read call to the PSM  160  so that the data block is read from the PSM  160 , or from a compartmentalized cache  177 . 
       FIG. 7  depicts a block diagram of a computer system for the active read-writable standby database server system of  FIG. 1 , capable of implementing methods for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database of  FIGS. 4-6 , in accordance with embodiments of the present invention. The computer system  500  may generally comprise a processor  591 , an input device  592  coupled to the processor  591 , an output device  593  coupled to the processor  591 , and memory devices  594  and  595  each coupled to the processor  591 . The input device  592 , output device  593  and memory devices  594 ,  595  may each be coupled to the processor  591  via a bus. Processor  591  may perform computations and control the functions of computer  500 , including executing instructions included in the computer code  597  for the tools and programs capable of implementing a method for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database, in the manner prescribed by the embodiments of  FIGS. 4-6  using the active read-writable standby database server system of  FIGS. 1-3 , wherein the instructions of the computer code  597  may be executed by processor  591  via memory device  595 . The computer code  597  may include software or program instructions that may implement one or more algorithms for implementing the methods for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database, as described in detail above. The processor  591  executes the computer code  597 . Processor  591  may include a single processing unit, or may be distributed across one or more processing units in one or more locations (e.g., on a client and server). 
     The memory device  594  may include input data  596 . The input data  596  includes any inputs required by the computer code  597 . The output device  593  displays output from the computer code  597 . Either or both memory devices  594  and  595  may be used as a computer usable storage medium (or program storage device) having a computer readable program embodied therein and/or having other data stored therein, wherein the computer readable program comprises the computer code  597 . Generally, a computer program product (or, alternatively, an article of manufacture) of the computer system  500  may comprise said computer usable storage medium (or said program storage device). 
     Memory devices  594 ,  595  include any known computer readable storage medium, including those described in detail below. In one embodiment, cache memory elements of memory devices  594 ,  595  may provide temporary storage of at least some program code (e.g., computer code  597 ) in order to reduce the number of times code must be retrieved from bulk storage while instructions of the computer code  597  are executed. Moreover, similar to processor  591 , memory devices  594 ,  595  may reside at a single physical location, including one or more types of data storage, or be distributed across a plurality of physical systems in various forms. Further, memory devices  594 ,  595  can include data distributed across, for example, a local area network (LAN) or a wide area network (WAN). Further, memory devices  594 ,  595  may include an operating system (not shown) and may include other systems not shown in  FIG. 7 . 
     In some embodiments, the computer system  500  may further be coupled to an Input/output (I/O) interface and a computer data storage unit. An I/O interface may include any system for exchanging information to or from an input device  592  or output device  593 . The input device  592  may be, inter alia, a keyboard, a mouse, etc. The output device  593  may be, inter alia, a printer, a plotter, a display device (such as a computer screen), a magnetic tape, a removable hard disk, a floppy disk, etc. The memory devices  594  and  595  may be, inter alia, a hard disk, a floppy disk, a magnetic tape, an optical storage such as a compact disc (CD) or a digital video disc (DVD), a dynamic random access memory (DRAM), a read-only memory (ROM), etc. The bus may provide a communication link between each of the components in computer  500 , and may include any type of transmission link, including electrical, optical, wireless, etc. 
     An I/O interface may allow computer system  500  to store information (e.g., data or program instructions such as program code  597 ) on and retrieve the information from computer data storage unit (not shown). Computer data storage unit includes a known computer-readable storage medium, which is described below. In one embodiment, computer data storage unit may be a non-volatile data storage device, such as a magnetic disk drive (i.e., hard disk drive) or an optical disc drive (e.g., a CD-ROM drive which receives a CD-ROM disk). In other embodiments, the data storage unit may include a knowledge base or data repository  125  as shown in  FIG. 1 . 
     As will be appreciated by one skilled in the art, in a first embodiment, the present invention may be a method; in a second embodiment, the present invention may be a system; and in a third embodiment, the present invention may be a computer program product. Any of the components of the embodiments of the present invention can be deployed, managed, serviced, etc. by a service provider that offers to deploy or integrate computing infrastructure with respect to active read-writable standby database systems and methods. Thus, an embodiment of the present invention discloses a process for supporting computer infrastructure, where the process includes providing at least one support service for at least one of integrating, hosting, maintaining and deploying computer-readable code (e.g., program code  597 ) in a computer system (e.g., computer  500 ) including one or more processor(s)  591 , wherein the processor(s) carry out instructions contained in the computer code  597  causing the computer system to provide an active read-writable standby database server system for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database. Another embodiment discloses a process for supporting computer infrastructure, where the process includes integrating computer-readable program code into a computer system including a processor. 
     The step of integrating includes storing the program code in a computer-readable storage device of the computer system through use of the processor. The program code, upon being executed by the processor, implements a method for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database. Thus, the present invention discloses a process for supporting, deploying and/or integrating computer infrastructure, integrating, hosting, maintaining, and deploying computer-readable code into the computer system  500 , wherein the code in combination with the computer system  500  is capable of performing a method for creating a standby database with read/write access capability while also maintaining a data consistency with a primary database. 
     A computer program product of the present invention comprises one or more computer readable hardware storage devices having computer readable program code stored therein, said program code containing instructions executable by one or more processors of a computer system to implement the methods of the present invention. 
     A computer system of the present invention comprises one or more processors, one or more memories, and one or more computer readable hardware storage devices, said one or more hardware storage devices containing program code executable by the one or more processors via the one or more memories to implement the methods of the present invention. 
     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. 
     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 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. 8 , 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,  54 B,  54 C and  54 N shown in  FIG. 8  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. 9 , a set of functional abstraction layers provided by cloud computing environment  50  (see  FIG. 8 ) is shown. It should be understood in advance that the components, layers, and functions shown in  FIG. 6  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 active read-writable standby database creation  96 . 
     While embodiments of the present invention have been described herein for purposes of illustration, many modifications and changes will become apparent to those skilled in the art. Accordingly, the appended claims are intended to encompass all such modifications and changes as fall within the true spirit and scope of this invention. 
     The descriptions of the various embodiments of the present invention 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.