摘要:
A method, computer program product and computing device for promoting reuse of previously generated access plans are disclosed. SQL statements containing literals are amended so as to substitute a parameter marker for each literal. Amended statements are provided to the DBMS along with parameters including the substituted literals and a substitution indicator indicating that the substitution has been performed. The DBMS assesses the soundness of the substitutions that are performed. Soundness may be measured in terms of the semantic correctness of the amended statement and the likelihood that the literal substitution will improve DBMS efficiency. If a substitution is unsound, the DBMS may obtain and optimize the original version of the amended SQL statement. Otherwise, the amended statement is optimized. Advantageously, SQL statements originally differing only in the value of one or more literals may become functionally equivalent, and the reuse of cached, previously generated access plans is thus promoted.
摘要:
A database server helps to streamline the retrieval of LOB values by deciding to send a locator in replacement of the LOB value, or the LOB value itself, depending upon the specific LOB value being retrieved. A threshold value is determined in a fetch query, and the LOB sizes below that threshold are sent as values in a corresponding fetch response, and the lengths above are sent as locators in the fetch response. Indicators are inserted in a fetch parameter of the response to inform the receiving client the form of retrieval that was used for each requested LOB value being returned.
摘要:
A system provides efficient multi-protocol database transaction processing in a multi-communications protocol and multi-programming model computing environment. The system separates the source and the target functionalities, and uses generic function names linked to function pointers, in order to permit the source layer to call embedded functions in the target layer. As an example, the system provides a source layer code path that includes embedded call-back functions and embedded generic function names. A target layer code path is set to include embedded functions and generic call-back function names. A function pointer array permits the source layer code path to call functions embedded in the target layer code path using the generic function names. A call-back function pointer array permits the target layer code path to call the call-back functions embedded in the source layer code path using the generic call-back function names.