Abstract: One example discloses a database management system that can comprise a memory for storing computer executable instructions and a processing unit for accessing the memory and executing the computer executable instructions. The computer executable instructions can comprise a query data collector to access a query repository table to determine if a first query plan for a first configuration executed on a relational database has a lowest resource cost of execution between the first query plan and a second query plan for a second configuration. The query repository table can include a plurality of query records with annotated query plans, each annotated query plan comprising text sufficient to generate a query plan of a certain form.

Abstract: Validating a query execution includes determining whether a condition of a query has changed and recompiling the query if the condition has changed.

Abstract: There is provided a computer-executed method of executing a rowset insert against a database. The method comprises receiving a structured query language statement (SQL) specifying the rowset insert. Additionally, the method comprises raising an error for a first row of the rowset insert. The method also comprises updating a table for a second row of the rowset insert. Further, the method comprises updating a materialized view of the table based on the second row. Additionally, the method comprises performing a commit to the database. The table comprises the second row, and the updated materialized view is consistent with the table.

Abstract: There is provided a computer-implemented method of optimizing a query. An exemplary method comprises receiving a first query configured to generate a result set. The query may comprise an operation for an outer table, a first predicate, and a second predicate. The second predicate may comprise a subquery correlated to the operation. Additionally, the first predicate and the second predicate may be disjunctive. The exemplary method also comprises generating a first query tree representing the first query, and generating a second query tree representing a second query. The second query may be configured to generate the result set, and may not comprise the subquery. The exemplary method additionally comprises generating a query plan based on the second query tree.

Abstract: There is provided a computer-executed method of executing a rowset insert against a database. The method comprises receiving a structured query language statement (SQL) specifying the rowset insert. Additionally, the method comprises raising an error for a first row of the rowset insert. The method also comprises updating a table for a second row of the rowset insert. Further, the method comprises updating a materialized view of the table based on the second row. Additionally, the method comprises performing a commit to the database. The table comprises the second row, and the updated materialized view is consistent with the table.

Abstract: One example discloses a database management system that can comprise a memory for storing computer executable instructions and a processing unit for accessing the memory and executing the computer executable instructions. The computer executable instructions can comprise a query data collector to access a query repository table to determine if a first query plan for a first configuration executed on a relational database has a lowest resource cost of execution between the first query plan and a second query plan for a second configuration. The query repository table can include a plurality of query records with annotated query plans, each annotated query plan comprising text sufficient to generate a query plan of a certain form.

Abstract: There is provided a computer-implemented method of optimizing a query. An exemplary method comprises receiving a first query configured to generate a result set. The query may comprise an operation for an outer table, a first predicate, and a second predicate. The second predicate may comprise a subquery correlated to the operation. Additionally, the first predicate and the second predicate may be disjunctive. The exemplary method also comprises generating a first query tree representing the first query, and generating a second query tree representing a second query. The second query may be configured to generate the result set, and may not comprise the subquery. The exemplary method additionally comprises generating a query plan based on the second query tree.