International Business Machines Corporation

Hai Jun Shen

Chang Sheng Liu

Yan Xu

Jun Hui Liu

Lei Cui

Ya Qiong Liu

Ying Qi Pan

Liam Loucks

Hui Guo

Ping Liu

Yao M Wang

A data virtualization layer (DV) receives a join query request related to a plurality of tables respectively stored in a plurality of distributed database servers. A plurality of candidate query plans for the join query request is generated where each of the plurality of candidate query plans indicates an order for transmitting the tables respectively stored in the database servers to the DV. For each of the plurality of candidate query plans, a query cost for the candidate query plan is calculated based on a data amount of the tables to be transmitted according to the candidate query plan. From the plurality of candidate query plans, a query plan is determined for the join query request which has a lowest query cost.

Cross-database join query

An approach is provided for optimizing multi-datasource queries in a networked computing environment. A procedure that contains a set of queries designed to access a specific set of data from a plurality of datasources in a virtualized hybrid storage environment (e.g., a virtualized hybrid cloud) is obtained. A set of mapped store procedures is created for the set of datasources referenced in the procedure. Each mapped store procedure includes a subset of queries that are applicable to a corresponding datasource from the set of queries in the procedure. These mapped store procedures are forwarded to the corresponding datasource for storage on the corresponding datasource. In response to a running of the procedure, execution of the mapped store procedure is commenced on each of the corresponding datasources on which they are stored.

Remote datasource-based optimization of procedure-based multi-datasource queries

An approach for optimizing statistical query performance. The approach receives a structured query language set. The approach identifies a first set of parameters associated with the statements of the SQL set. The approach creates a merged SQL statement based on one or more matching parameters of SQL statements in the SQL set. The approach binds a second set of parameters associated with the merged SQL statement to the merged SQL statement. The approach generates a SQL statement based on the merged SQL statement. The approach generates a remote SQL statement based on the SQL statement. The approach executes a commit statement on the remote SQL statement.

Database query performance improvement

Methods, computer program products, and systems are presented. The methods include, for instance: collecting real time system statistics on a system environment in a remote platform running a remote data source amongst a plurality of remote data sources of a virtual database. Real time data source statistics on one or more data source objects from the remote data source of the virtual database is also gathered. A global catalog of the virtual database is updated with the real time system statistics and the real time data source statistics. An access plan to process a query to the virtual database is optimized based on the real time system statistics and the real time data source statistics and a response is produced based on the access plan, with improved performance and reduced cost.

Optimizing query performance in virtual database

A computer-implemented method reduces the number of character set conversions in a distributed data virtualization system. The method includes receiving, from a first application, a first request for a set of data, including a requested codepage, stored in a first data source of a plurality of data sources. The method includes obtaining, by a connector, from the first data source, a first codepage associated with the first data source, which identifies a character set associated with the set of data. The method also includes adding a virtual coded character set identifier (VCCSID) in a first catalog entry of a catalog, wherein the first VCCSID is added to a nickname column of the catalog. The method includes obtaining and sending the set of data to the data application while allowing maximum of one codepage conversion.

Reducing character set conversion

A federated database-management system receives an SQL query or other type of data-access request. The federated system's host DBMS parses, rewrites, and optimizes the request into an optimal data-access plan, then determines which portions of the plan require access to data stored on the federated systems' remote databases. The federated host partitions the plan into subplans that each represent instructions of the original data-access request that were directed to a corresponding remote database of the federated DBMS. Each subplan is then transmitted to its corresponding remote database, which directly executes the subplan and returns results to the host. If necessary, a subplan is translated from an original generic access-plan format into a database-specific format required by its corresponding remote database.

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Beijing, China

Hai Jun Shen