公开(公告)号：CA2419982A1

公开(公告)日：2004-08-26

申请号：CA2419982

申请日：2003-02-26

Applicant: IBM CANADA

Inventor： COTNER CURT L ,  OSTLER PAUL A ,  BEGG ROBERT A ,  VINCENT TIMOTHY J ,  GROSS BRENT P

IPC: G06F7/00 ,  G06F17/30

Abstract: A database server helps to streamline retrieval of lob values by making the decision of sending 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 lob sizes below that threshold are sent as values in a corresponding fetch response, and 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 about which form of retrieval was used for each requested lob value being returned. The use of the indicators provides for sending lob values to the client when the lob value is considered small, and sending the locator when the lob values a re considered large in comparison to the threshold value. Therefore, the use of distinct indicators in the parameter of the response provides for the server system making a dynamic decision of sending either the LOB locator or an inline LOB value in the response, depending upon the specific value of the LOB in comparison to the threshold value. For example, the LOB values below the threshold are sent as values in columns or fetch answers of the response, while the LO B values above the threshold are sent as locators in place of the LOB values. The fetch paramet er uses the distinct indicator values to help inform the client of the form of retrieval present in the response as a result of the query.

公开(公告)号：CA2408474A1

公开(公告)日：2004-04-17

申请号：CA2408474

申请日：2002-10-17

Applicant: IBM CANADA

Inventor： KIRTON JO-ANNE M ,  VINCENT TIMOTHY J ,  BEGG ROBERT A

IPC: G06F17/30 ,  G06F9/44

Abstract: Efficient multi-protocol database transaction processing is enabled by separating source and target functionality, and using generic function names linked to function pointers to permit the source layer to call embedded functions in the target layer, and vice versa. Adding new program models and/or new communications protocols is thus significantly simplified.

公开(公告)号：CA2382714A1

公开(公告)日：2003-10-19

申请号：CA2382714

申请日：2002-04-19

Applicant: IBM CANADA

Inventor： VINCENT TIMOTHY J ,  SCHIEFER KLAUS BERNHARD ,  O'CONNELL WILLIAM T ,  LIMOGES JOSEPH SERGE ,  BEGG ROBERT A ,  EVANS DOMINIQUE J

IPC: G06F17/30

Abstract: A method, computer program product and computing device for promoting reuse ofpreviously generated access plans in a relational DBMS 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 comprising 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 wi ll improve DBMS efficiency. If a substitution is unsound, the DBMS may obtain and optimize (i.e. select an access plan for) 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. Improvements in DBMS efficiency may thus be achieved .