Abstract: A database system receives a request from a user. The request invokes a data set function (DSF) and uses a property to be provided by the DSF. The database system determines that a function descriptor is available for the DSF. The function descriptor is expressed as markup language instructions. The function descriptor defines the property of the DSF. The database system uses the function descriptor to define a property for the DSF.

Abstract: Execution of a query invoking an analytical function (AF) is optimized. The query includes a join operation between an AF table and an AuxiliaryTable. A determination is made that the AF includes a plurality of AF properties. Query-level properties about the query are inferred. A determination is made to change an order of the join operation from the plurality of AF properties and query-level properties.

Abstract: One or a soft correlation of a database can be adjusted (e.g., modified, replaced, overwritten) for use with respect to one or more record(s) of the database associated with the soft correlation, by considering at least one or more violations of the soft correlations in the one or more of records database records associated with the soft correlation. In addition, an adjusted soft correlation can be stored and used for optimizations of database queries pertaining to one or more records associated with the adjusted soft correlation. Typically, the adjusted soft correlation is adjusted by at least considering the violations of an original soft correlation in the one or more records relating to the database queries.

Abstract: One or a soft correlation of a database can be adjusted (e.g., modified, replaced, overwritten) for use with respect to one or more record(s) of the database associated with the soft correlation, by considering at least one or more violations of the soft correlations in the one or more of records database records associated with the soft correlation. In addition, an adjusted soft correlation can be stored and used for optimizations of database queries pertaining to one or more records associated with the adjusted soft correlation. Typically, the adjusted soft correlation is adjusted by at least considering the violations of an original soft correlation in the one or more records relating to the database queries.

Abstract: A database system receives a request from a user. The request invokes a data set function (DSF) and uses a property to be provided by the DSF. The database system determines that a function descriptor is available for the DSF. The function descriptor is expressed as markup language instructions. The function descriptor defines the property of the DSF. The database system uses the function descriptor to define a property for the DSF.

Abstract: Execution of a query invoking an analytical function (AF) is optimized. The query includes a join operation between an AF table and an AuxiliaryTable and includes determining that the AF includes a plurality of AF properties. Query-level properties about the query are inferred. It is determined to change an order of the join operation from the plurality of AF properties and query-level properties.

Abstract: Multiple cost models (e.g., a sub-operations costing model and logical-operations costing model) can be used to make cost estimations of execution of database queries in one and each one of the multiple heterogeneous database systems. As a result, a “hybrid” cost estimating mode can be used whereby two or more cost models can be used in a single database system in to order maximize the advantages and minimize the disadvantages of each of the cost models, thereby striving to achieve an optimal balance. In addition, cost estimation can be switched between a hybrid cost estimating mode and a single cost estimating mode. The switch can, for example, be made as a part of tuning phase, as more information about actual costs of execution of database queries becomes more available, or as a result of changes to the database system and/or it operations, and so on. As a result, a flexible cost estimating mechanism can also be provided.