Abstract:
The invention relates generally to the management of distributed databases, and more particularly to a method and an arrangement associated with managing database schemas and configuration of software that uses those schemas. The objective of this invention is to present a method and a system, which allows managing database schemas and application software in large distributed multi-database systems and avoiding problems that are related to the prior art systems. The objective of the invention is attained by using configuration manager apparatus ( 231 ), which is external to the configuration and databases being managed ( 200 ). The objective of the invention is preferably also attained by providing a mechanism for keeping multiple, possibly different database schemas and application software in synchronization. The external configuration management node ( 231 ) manages the configuration management replicas ( 203, 213, 223 ) in each part ( 201, 211, 221 ) of the distributed database system ( 200 ). These synchronized configuration management replicas comprise scripts that are used for creating and/or updating the schemas of the database nodes and configuration of software that uses these database nodes ( 202, 212, 222 )

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The invention relates generally to the management of distributed databases, and more particularly to a method and an arrangement associated with managing database schemas.  
         BACKGROUND ART OF THE INVENTION  
         [0002]    The following notions are used in this application:  
           [0003]    “Data management system” is an entity, which comprises one or more databases and/or data management systems, whereby the system is responsible for reading the data structures contained in the databases and/or data management systems and for changing these data structures.  
           [0004]    “Database” is an information structure, which comprises one or more data elements, and the use of which is controlled by the data management system. The invention is applicable both in relational databases and in databases of other forms, such as in object-oriented databases.  
           [0005]    “Data element” is an information structure, which can comprise other data elements or such data elements, which can be construed as atomary data elements. For instance, in a relational database data elements are represented by tables comprising rows. The rows comprise fields, which are typically atomary data elements.  
           [0006]    “Database operation” is an event, during which data elements are read from the database, during which data elements of the database are modified, during which data elements are removed from the database, and/or during which data elements are added to the database.  
           [0007]    “Transaction” is a plurality of database operations acting on the data elements. A transaction can also comprise further transactions.  
           [0008]    “Database Schema” is the structure of a database system, described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables.  
           [0009]    “Database Catalogue” logically partitions a database so that data is organized in ways that meet business or application requirements. Each logical database is a catalogue and contains a complete, independent group of database objects, such as tables, indexes, procedures and triggers. Each of these catalogues can act as a master or replica database. This makes it possible, for example, to create two or more replica databases into one physical database. It is also possible to have one or more catalogues in this same local database that represent master database(s).  
           [0010]    “Database Node” is a database catalogue, which has been defined to act as a master or replica and thus participates in a hierarchy of synchronized databases.  
           [0011]    “Master database” is a database catalogue in a database synchronization system that contains the official version of synchronized/distributed data. A master database can have multiple replica databases.  
           [0012]    “Replica database” is a database catalogue in a database synchronization system that contains a full or partial tentative copy of the master data.  
           [0013]    “Publication” is a set of data in a database catalogue that has been published in master database for synchronization to one or multiple replica databases.  
           [0014]    “Synchronization” is operation between replica and master database catalogues in which changed data is exchanged between the catalogues. In one known embodiment, this means propagation of Intelligent transactions from replica to master and subscribing to a publication to download changed data from master to replica, [1] EP 0 860 788.  
           [0015]    “Schema revision” is a snapshot version of a schema that is identifiable by logical name or version number.  
           [0016]    “Schema script” is a script that creates a schema or creates a new revision of an existing schema of a database node.  
           [0017]    “Schema subscript” is a schema script that is executed from another schema script.  
           [0018]    “Schema script publication” is a system publication that contains the schema scripts of the database hierarchy.  
           [0019]    A schema is a representation of the structure of the database that illustrates what kind of data is stored in the database. In distributed database management environments, it must be possible to distribute new schemas as well as modify the existing schemas of the databases of the system in a flexible and controllable manner.  
           [0020]    [0020]FIG. 1 illustrates an example of prior art database arrangement  100 . The database system includes a server  101  with an application master database  102 . This application master database includes a schema master of the data stored in the database. The database system also includes two servers  111  and  121  with application replica databases  112 ,  122 . The application replica databases can maintain a full or partial copy (replica) of the application master database servers&#39; data using suitable data synchronization technology, such as functionality disclosed in patent application document [1] EP 0 860 788. The application replica databases include schemas  113 ,  123 , which may be a full or partial copy of the schema  103  of the application master database. Some prior art solutions for managing schemas in distributed database systems are described in documents [2] U.S. Pat. No. 5 806 066, [3] WO 00/45286 and [4] WO 00/04445.  
           [0021]    In the prior art implementations schema upgrades are made in the master and these upgrades are distributed to the replicas transparently using some hard-coded rules. This approach introduces some problems that make operating large multi-database systems difficult:  
           [0022]    There is no possibility in prior art implementations to control the schema upgrade process programmatically. For instance, sometimes the nature of a schema modification operation require that services for all on-line users of the database are disconnected while the schema is being upgraded. This requires programmatic control over the upgrade process in replica databases.  
           [0023]    There is no overall view about the upgrade status of different databases of the system. Failed upgrades are not reported anywhere and the system operator does not necessarily know, which replicas have upgraded to new revision and which have not yet done so.  
           [0024]    If the automatic upgrade fails, there is no possibility for error handling and system recovery. There is neither a possibility to prevent such errors. Typically the replica database must be recreated from scratch in this kind of situation.  
           [0025]    Upgrading a system where different replicas can have different schemas and where replicas can have local tables that are not defined in the master is a difficult task.  
           [0026]    The prior art technology does not support outsourcing the runtime configuration control of distributed systems to third parties.  
           [0027]    For these reasons, the database schemas of prior art distributed systems are typically not well manageable.  
         SUMMARY OF THE INVENTION  
         [0028]    The objective of this invention is to present a method and an arrangement, which allows managing database schemas and related application software configuration in large distributed multi-database systems and avoiding said problems that are related to the prior art systems.  
           [0029]    The objective of the invention is attained by using a schema and software configuration manager apparatus, which is external to the database nodes and software being managed. This configuration manager apparatus is here referred to as “schema and software configuration management node”. The objective of the invention is preferably also attained by providing a mechanism for keeping multiple, possibly different database schemas and their applications in synchronization. The external configuration management node manages the schema and software configuration management replicas in each server of the distributed database system. These synchronized schema/application configuration management replicas comprise scripts that are used for creating and/or updating the schemas of the database nodes and managing the configurations of applications that use the database node. The invention thus provides a solution to the problem of managing schemas of distributed databases and applications that use those databases.  
           [0030]    The database schema and application configuration management database node is typically a separate database node that can reside in a database server same as or different from the application database server. If the hierarchies of application database nodes and management database nodes are identical, the management database node can be made a part of the application database node.  
           [0031]    One idea of the invention is to utilize relational data synchronization mechanism along with application logic to manage schemas of potentially large number of application database nodes. This allows building large distributed systems with separate but still closely integrated configuration control functionality.  
           [0032]    Inventive features in some embodiments according to the invention are:  
           [0033]    Extracting the schema management mechanism from the application&#39;s schema to an independent entity,  
           [0034]    Managing all different schemas and applications of a distributed system in one location,  
           [0035]    Utilizing incremental synchronization mechanism for distributing the new and modified schema and software configuration scripts to the nodes of the system, and  
           [0036]    Utilizing a revision name for detecting the need for schema and application configuration data synchronization, i.e. the schema is upgraded if its revision property does not match with master&#39;s respective property.  
           [0037]    The “schema management” means here that database objects such as tables, indices, procedures, triggers etc. are amended, added or deleted. The “application configuration management” means here that application software and/or its configuration parameters and other data needed to run the application, are amended, added or deleted.  
           [0038]    A database system may include servers, smart terminals, other terminals and network nodes. A network node may be e.g. a base station controller, access router, optical network router, radio network controller (RNC) controlling a base station controller (BSC), etc. These parts of the distributed database system may have a wireless or wireline connection to the other parts of the system. If a network-based server is used, the application can, in some embodiments, be located and invoked by using the Uniform Resource Locator (URL) of the server. The schema/application configuration management node may also be a server, a client terminal or other node mentioned above, with a wireless or wireline connection to the other servers and terminals, which include parts of the distributed database. The database may be Oracle, Solid, Times Ten, Polyhedra, Clustra or any other database.  
           [0039]    With the present invention it is thus possible to remotely manage schemas of distributed databases stored in terminals and various servers and keep the schemas and applications that use the schemas automatically in synchronization. The present invention has several advantages over the prior art solutions:  
           [0040]    It is possible to manage the runtime configuration control of distributed systems externally and therefore outsourced services of third parties can be used for providing this function.  
           [0041]    It is possible to control the schema and application configuration upgrade process programmatically. For instance, sometimes the nature of a schema modification operation require that services for all on-line users of the database are disconnected while the schema is being upgraded. This requires programmatic control over the upgrade process in replica database nodes.  
           [0042]    It is possible to have an overall view about the upgrade status of different database nodes of the system. Failed upgrades can be reported or prevented, and the system operator has the information, which replicas and masters have upgraded to new revision and which have not yet done so.  
           [0043]    If the automatic upgrade fails, there is a possibility for error handling and system recovery. There is also a better possibility to prevent such errors, because the control of the schemas of the database system is centralized. It is possible to prevent situations where it is necessary to recreate replica database from scratch.  
           [0044]    It is also possible to upgrade a system where different replicas can have different schemas and where replicas can have local tables or local private data in any shared table that are not defined or managed in the master.  
           [0045]    Further, together with updating schemas of a database system, it is also possible to update other information of a node using the same updating route and procedures. This may include, for example, updating configuration scripts, updating configuration programs and changing application binaries into a new version level. Schema scripts can also include DML (Data Manipulation Language) or DDL (Data Definition Language) scripts, or any other data manipulation scripts. In some embodiments this is used to set up version information for applications to detect the need for update.  
           [0046]    The method according to the invention for managing schemas and/or application configuration in at least one database system comprising at least one application master database and at least one application replica database, wherein at least one of said databases comprises a schema of the data stored in the database, is characterized in that the at least one schema and/or application configuration is managed externally of said at least one application master database and at least one application replica database, and that at least one said database is distributed on single or multiple servers.  
           [0047]    The invention also relates to a storage media comprising a stored, readable computer program, which is characterized in that the program comprises instructions for controlling a data management system or components thereof to implement the method according to the invention.  
           [0048]    The invention further relates to a configuration management arrangement for at least one database system comprising at least one server with application master database and at least one server with application replica database, wherein at least one database comprises a schema of the data stored in the database, which is characterized in that the arrangement comprises a configuration management node for managing a database schema and/or application configuration of said at least one database server, wherein said configuration management node is separate from said at least one application master database.  
           [0049]    The invention further relates to a configuration management node for at least one database system, comprising means creating and/or updating schemas and/or application configuration of a database system comprising at least one database in at least one database server, wherein the configuration management node is external of said at least one database server.  
           [0050]    The best mode of the invention is considered to be a separate updating of replica schema from the master schema.  
           [0051]    Some embodiments of the invention are described in the dependent claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0052]    Next the invention is described in more detail with reference to embodiments shown as examples and to the enclosed figures, in which:  
         [0053]    [0053]FIG. 1 illustrates a distributed database system according to the prior art,  
         [0054]    [0054]FIG. 2 a  illustrates the basic units of an exemplary configuration management system according to the invention, wherein the application database hierarchy is different from the schema and application configuration management database hierarchy,  
         [0055]    [0055]FIG. 2 b  illustrates the basic units of an exemplary configuration management system according to the invention, wherein the application database hierarchy is the same as the schema and application configuration management database hierarchy,  
         [0056]    [0056]FIG. 3 illustrates a flow diagram of exemplary steps setting up master database according to the invention;  
         [0057]    [0057]FIG. 4 illustrates a flow diagram of exemplary steps for setting up and registering replica database and installing application software according to the invention;  
         [0058]    [0058]FIG. 5 illustrates a flow diagram of exemplary steps for upgrading the master database schema and application configuration according to the invention;  
         [0059]    [0059]FIG. 6 illustrates a flow diagram of exemplary steps for upgrading the replica database schema and application configuration according to the invention;  
         [0060]    [0060]FIG. 7 illustrates a flow diagram of exemplary steps according to the invention for upgrading the master database schema and application configuration after a replica database schema has changed;  
         [0061]    [0061]FIG. 8 illustrates an exemplary system environment where the invention can be applied; and  
         [0062]    [0062]FIG. 9 illustrates a hierarchic system for managing database schemas and application configurations. 
     
    
     DETAILED DESCRIPTION  
       [0063]    [0063]FIG. 1 was described in the prior art description above. FIG. 2 a  shows an example of an arrangement according to the invention in a case where the application database hierarchy is different from the schema and application configuration management database hierarchy. The arrangement comprises three main components; application master database server  201 , application replica database servers  211 ,  221 , and schema management node  231 . Application master database node  202  and replica database nodes  212 ,  222  form a distributed system, wherein the application replica database nodes can maintain a full or partial copy (replica) of the application master database servers&#39; data using suitable data synchronization technology, such as functionality disclosed in patent application document [1] EP 0 860 788. The arrow lines between the blocks mean synchronization relationship between the database servers.  
         [0064]    The database schemas are managed by the configuration management node  231 .  
         [0065]    The configuration management node  231  includes a configuration management application  234  for managing the schemas and application configuration of the database system. There is also a configuration management master  233  stored in the configuration management node, and replicas  203   213 ,  223  of the configuration management master are stored into database servers  201 ,  211 ,  221  of the database system. It is also possible that some application database server does not have a schema management replica if the configuration management data is reliably and quickly available from some other node, such as configuration management master, of the network.  
         [0066]    The configuration management replicas may be full or partial copies of the configuration management master  233 . The configuration management replicas include scripts for creating and/or updating the schemas and/or application configuration of the databases. The updating between the configuration management master and the configuration management replicas can be made using the synchronization functionality of the servers [1]. Other methods may include direct transfer of schema&#39;s managed data from master to replica, or any other methods of information exchange.  
         [0067]    [0067]FIG. 2 b  shows an example of an arrangement according to the invention in a case where the application database hierarchy is the same as the schema and application configuration management database hierarchy. When the database hierarchies are identical, i.e. both application replica and configuration management replica synchronize their data from the same master node, the application and configuration management replicas can be implemented as one replica node.  
         [0068]    In the following exemplary methods for remote configuration management according to the invention are described in more detail referring to FIGS.  3 - 7 .  
         [0069]    [0069]FIG. 3 illustrates a method for setting up master database. In step  302  the database schema is defined using configuration management application and stored to the schema management master database, step  303 . If the application database hierarchy is different from configuration database hierarchy, two new, empty logical database nodes are created to the database server where the application master database will reside, step  304 . If the hierarchies are identical, these two nodes can be combined into one. In step  306  one of the empty database nodes is dedicated to be the replica node of the configuration management master database and registered with the master. As part of the registration, the identification data, e.g. schema name, of the new application database node is sent to the configuration management master database node. The newly created configuration management replica is then synchronized with its master database in step  308 . This downloads the schema creation scripts and possibly also application configuration data such as software binaries and installation programs of the application master to the database server. Next the schema of the application master database node is created using the scripts that were downloaded to the new replica database node,  310 . At this phase, also the software configuration data can be extracted from the database and installed,  312 . Now the master database node along with the application is ready for use.  
         [0070]    [0070]FIG. 4 illustrates a method for setting up and registering replica database. First in step  402  the database schema and application configuration of the replica database node is defined in using the configuration management application and stored,  403 , to the configuration management master database node. This step is typically made at the same time when the configuration of the application&#39;s master database schema and applications are defined.  
         [0071]    In step  404  two new, empty database nodes are created to the database server where the application replica database will reside. One of the new empty databases of this server is dedicated to be the replica node of the configuration management master database and registered with the configuration management master, step  406 . As part of the registration, the identification data, e.g. schema name of the new application database is sent to the configuration management master database node. Next in step  408  the newly created configuration management replica is synchronized with its master database. This downloads the schema creation scripts of the replica and possibly also application configuration data and software to the database node. In step  409  the application replica database node registers itself with the application master database using registration scripts found from the schema management replica of the server. The schema of the application replica database node is created using the scripts that were downloaded to the configuration management replica database node,  410 . Finally, the replica application software is installed,  412 . If the database hierarchies are identical, i.e. both application replica and configuration management replica synchronize their data from the same master node, the application and configuration management replicas can be implemented as one replica node.  
         [0072]    [0072]FIG. 5 illustrates a method for upgrading the master database schema. First in step  502  a set of scripts is created for a new revision of the master database schema in the configuration management application, and stored to the configuration management master,  503 . In step  504  the configuration management replica database node of the application master server subscribes the data of the new revision from the configuration management master by synchronizing itself with the master database node. The application master schema is updated by running the scripts of the new revision,  506 . The scripts are found from the configuration management replica database of the server. After this, the application configuration can be upgraded by using the application configuration data and software that was downloaded during the synchronization,  507 . During the execution of the scripts, log entries can be stored to a table of the configuration management replica. After successful execution of the scripts, the revision level of the application master schema is upgraded. Next in step  508  the log entries written in step  506  are propagated to the configuration management master by synchronizing the configuration management replica database node. The system administrator can review the success of the upgrade by viewing the log entries using the configuration management application,  510 .  
         [0073]    [0073]FIG. 6 illustrates a method for upgrading the replica database schema and/or application configuration after the master database schema and/or application configuration has been upgraded according to FIG. 5. First in step  602  a set of a new revision (that matches with the earlier created master revision) of the application replica database schema is created in the configuration management application and stored,  603 , to the configuration management master. The application replica tries to synchronize with the application master database node in step  604 , but fails because the schema of the application master database node has been upgraded to a new revision level. Alternatively, configuration management node can inform the application replica database about the need to upgrade the schema. The configuration management replica database of the application replica server subscribes the upgrade scripts of the new schema and application configuration revision from the configuration management master by synchronizing itself with the master database node, step  605 .  
         [0074]    Next in step  606  the application replica schema is updated by running the scripts of the new revision. The scripts are found from the configuration management replica database of the server. After this, the application configuration can be upgraded by using the application configuration data and software that was downloaded during the synchronization,  607 . During the execution of the scripts, log entries can be stored to a table of the configuration management replica. After successful execution of the scripts, the revision level of the application replica schema is upgraded. The log entries written in step  606  are propagated to the schema management master by synchronizing the configuration management replica database node, step  608 . Now that the revision levels of the application master and the replica databases are the same, the application replica database node can synchronize with the application master database node again,  609 . The system administrator can review the success of the upgrade by viewing the log entries using the configuration management application,  610 .  
         [0075]    [0075]FIG. 7 illustrates a method for upgrading the master database schema after a replica database schema has changed (a replica database schema can change similarly as shown in FIG. 5 for the master database schema). First in step  702  a set of a new revision (that matches with the earlier created replica revision) of the application master database schema is created in the configuration management application and stored,  703 , to the configuration management master. The application replica tries to synchronize with the application master database in step  704 , but fails because the schema of the application replica database has been upgraded to a new revision level. The configuration management replica database node of the application master server subscribes the upgrade scripts of the new revision from the configuration management master by synchronizing itself with the master database node, step  705 .  
         [0076]    Next in step  706  the application master schema and possibly also application configuration is updated by running the scripts of the new revision. The scripts are found from the configuration management replica database of the server. During the execution of the scripts, log entries can be stored to a table of the configuration management replica. After successful execution of the scripts, the revision level of the application master schema is upgraded. The log entries written in step  706  are propagated to the configuration management master by synchronizing the configuration management replica database node, step  708 . Now that the revision levels of the application master and the replica database nodes are the same, the application replica database can synchronize with the application master database node again,  709 . The system administrator can review the success of the upgrade by viewing the log entries using the configuration management application,  710 .  
         [0077]    [0077]FIG. 8 illustrates an example of an equipment environment where the present invention can be applied. The database system comprises the server for application master database node  801 , and several servers for application replica database nodes. The application replica database servers include an online station  811 , to which a laptop terminal  841  and WAP terminal  851  are connected. There is also a data-warehouse including the application replica database node. A separate configuration management node  831  manages configurations of all the database servers of the database system. The configuration management node  831  has therefore individual synchronization connections to all blocks  801 ,  811 ,  821 ,  841  and  851 .  
         [0078]    [0078]FIG. 9 illustrates an example of a hierarchic system where several database systems a, b, c have their respective schema management nodes  931   a ,  931   b  and  931   c  which manage the schemas of the respective database nodes. The database systems have a common configuration management node  931  for managing schemas and application configuration of all database systems a, b and c. The configuration management nodes  931   a ,  931   b  and  931   c  of the individual database systems are thus replicas of the main configuration management node  931 . If the hierarchy of the application database is the same as the hierarchy of the configuration management databases, the management database may be included as part of the application database.  
         [0079]    A system according to the invention can be implemented by a person skilled in the art with state of the art information technology and communication technology components. A person skilled in the art can implement the functions according to the invention by arranging and programming such components to realize the inventive functions.  
         [0080]    For example, the invention can be implemented to work in a telecommunication system, which is complient with at least one of the following: TCP/IP, CDMA, GSM, GPRS, WCDMA, UMTS, Teldesic, Iridium, Inmarsat, WLAN and imode.  
         [0081]    It is also possible to use a standardized operating system in the terminals and servers. The operating system of a terminal can be, for example, Unix, MS-windows, EPOC, NT, MSCE, Linux, PalmOS and GEOS. The servers for application master database and schema management application may preferably have at least one of the following operating systems: Unix, MS-windows, NT and Linux.  
         [0082]    To a person skilled in the art it is obvious that in order to have an illustrative description the above presented exemplary embodiments have a structure and a function, which are relatively simple. By applying the model presented in this application it is possible to design different and very complicated systems, which in obvious ways to the expert, utilise the inventive idea presented in this application.  
         [0083]    One should note that, although embodiments concerning schema configuration management are described, the invention is also well applicable to application configuration management.  
       CITED DOCUMENTS  
       [0084]    [1] EP 0 860 788; Intelligent Transaction, Solid Information Technology Oy.  
         [0085]    [2] U.S. Pat. No. 5 806 066; Method of Integrating Schemas of Distributed Heterogeneous Databases, Bull HN Information Systems Inc.  
         [0086]    [3] WO 00/45286; Method and Apparatus for Distributed Database Access, Genrad, Inc.  
         [0087]    [4] WO 00/04445; Object Oriented Generic Schema to Support Database Operations in Multi-tier Architecture, OMR Systems Corporation, Inc.