摘要:
A method enables a data manipulation action to occur between data from a data source and data in a table in a database, where the database is remote from the data source. The method includes the steps of: determining whether data from the data source comprises unique values, and if not, enabling a caching procedure. The caching procedure obtains values from the data source and transmits a query to a database management system which controls the table, including a value from the data source. A result set is received from the table, is cached, and additionally is stored for purposes of responding to the query. Thereafter, if a value from the data source is retrieved which is identical to a previously retrieved data source value, the cached corresponding result set is utilized, in lieu of transmitting a further query to the table.
摘要:
A heterogeneous database system includes plural databases, one database acting as a system manager which performs functions to provide a transparent user interface that encompasses both the system manager database and other databases. The system manager includes a memory which stores (i) a database management procedure, (ii) a catalog of database functions that are supported by the plural databases, and (iii) a query optimizer procedure. A processor is responsive to a user query which requires data stored at a remote database, to execute the query optimizer procedure. The query optimizer procedure employs entries from the catalogue relating to database functions supported by both the system manager database and the remote database and establishes query plans for responding to the query. A first query plan is based upon execution at the remote database and a second query plan is based upon execution at the system manager database. The query optimizer then chooses one of the query plans in accordance with a determined criteria and causes the selected plan to be executed.
摘要:
A database management method enables an improved efficiency processing action in a computer wherein manipulation of data from a table is required in accord with a query request, wherein the table is stored remotely from said computer and at least some data in the table includes large data objects (LOBs). The method includes the steps of: responding to the request by transmitting a query to the table; configuring a result set from the table in response to the query, wherein the result set includes one or more unique identifiers of any LOB data associated with the result set; receiving the result set and performing a data manipulation action on data contained in the result set to form a response; transferring the response to the query requester; and accessing LOB data from the table that is referenced by the one or more unique identifiers in the result set and causing transfer of the LOB data to the query requester.
摘要:
An improved join operation is performed between data in at least two tables, with one of the tables stored in a remote database (hereafter "remote table") and another table stored in a local database (hereafter "local table"). The entry values in both the local table and the remote table are accessible in an ordered manner, based upon an order of the entry values. The method of the join operation generally includes the steps of: determining a count of a number of entry values that reside in the local table that are to be joined with entry values in the remote table; comparing the count with a threshold value, and (i) if the count exceeds the threshold value, issuing a query to the remote table to fetch a range of entry values therefrom, the range determined by the range of entry values to be joined from the local table; and (ii) if the count does not exceed the threshold value, issuing a query to the remote table to fetch each specific entry value that matches the entry values to be joined from the local table.
摘要:
A method, computer product, and system for rewriting database without decreasing pushdownability is provided. First, a pushdown analysis of the query in its entirety is performed prior to the application of any query rewrite rules in order to establish a baseline on pushdownability for the query. The results of this analysis is stored with the internal query representation. After each rule is applied to rewrite a portion of a query, that rewritten portion is analyzed again for pushdownability. If pushdownability is not decreased, then the rewritten query remains and the internal representation of the query is updated to reflect the pushdownability of that portion. If pushdownability is decreased, then an undo operation is applied to the rewritten portion of the query to back out the effects of the rule and leave the query in the same state as before the rewrite. Finally, additional rewrite rules that are directed to the heterogeneous database environment are also provided.
摘要:
A heterogeneous database system is described which includes plural database systems, one of the database systems acting as an interface (i.e., system manager). The system manager performs functions which provide an application program with transparent access to the entire database system. The system manager includes a memory for storing (i) a matrix of functional capabilities of each of the plural databases, (ii) a catalog of functions that are supportable by various databases and (iii) and entry matrix for providing an interface function between a user and the system manager. A processor is present in the system manager; and is responsive to a user entry, via the entry matrix, with respect to a functional capability of one of the plural databases, to alter a matrix of functional capabilities pertaining to the database. The alteration is carried out in accordance with a corresponding functional capability entry in the catalog. If a user entry is received which refers to a database for which no entry exists in the matrix of functional capabilities, the system manager presents an entry matrix in a form which reflects default functional capabilities. Thereafter, the default capabilities may be altered by a system administrator to reflect the capabilities of the new database.
摘要:
A method, computer product, and system for pushdown analysis during query plan generation is provided. Rather than do pushdown analysis for portions of a query that are query execution plan independent, the present invention provides pushdown analysis for features of a query that are plan dependent. This is done by evaluating a portion of the query plan for pushdownability to a remote database system; and if pushdownable to the remote database system, generating cost parameters for the portion of the plan if executed at a local database system and if executed at the remote database system. With both sets of cost parameters, the query optimizer has added information on which to select an optimal query plan.
摘要:
An application program interface at a local processor enables transparent access to both a local database and a remote database. The remote database includes (i) a remote DBMS which segregates data into distinct remote datatype categories and (ii) remote data functions which define functions that are executable by the remote DBMS with respect to categories of remote datatypes. The local processor includes a memory which stores (i) a local DBMS that includes local datatypes which segregate locally stored data into local datatypes; (ii) local functions which define actions that are executable by the local DBMS with respect to defined categories of the local datatypes, and (iii) tables which store a mapping between local datatypes and remote datatypes, and local functions and remote functions. The mapping between at least one local datatype and at least one remote datatype indicates that the remote datatype is to be transformed into a local defined datatype that is different than the remote datatype. A local processor employs the table to convert a received instance of the at least one remote datatype to a mapped local datatype and subjects data comprising the instance of the remote datatype to a local function which is not executable for the remote datatype. The application program interface further enables specification of a function to be carried out at the remote database with respect to data stored thereat, which function is not readily performable by the local processor.
摘要:
A method and system for collecting statistics on database tables. In one embodiment, the method includes identifying a plurality of tables for statistics collection, wherein each table of the plurality of tables are remote tables; examining at least one attribute for each table identified for statistics collection; prioritizing the tables for statistics collection based on the at least one attribute; and collecting statistics on the identified tables in a priority sequence.
摘要:
A system, method, and program product are provided that identifies a remote stored procedure stored in a remote database management system, and automatically generates a local stored procedure stored in a local database management system. To automatically generate the local stored procedure, local and remote metadata are gathered corresponding, respectively, to a local database management system and a remote database management system. The remote metadata is used to create a call statement to the remote stored procedure. The created invocation method maps input values, input to the local stored procedure, to input parameters of the remote stored procedure. Results in the local stored procedure are set by mapping the data returned from the remote stored procedure to the corresponding return values (e.g., parameters and result sets) in the local stored procedure values.