Optimizing command execution in database systems that provide support for updatable scrollable cursors
AssigneeInternational Business Machines Corporation
InventorsIqbal A. Goralwalla, Michael J. Winer, David C. Sharpe, Matthew A. Huras
Life of this patent
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Abstract
A procedure optimizes command execution in a database system. According to one embodiment, the database system stores data records on data pages, and provides an identifier for each data page. The identifier indicates when any of the data records contained in the data page were last modified. A data record is selected from a data page and copied to a second storage area. Verification that the selected data record has not been modified since the time that is was copied to the second storage area is based upon the identifier, and then the command is executed.
Claims22
A method for optimizing command execution in a database system, wherein data records are stored on a plurality of data pages therein, the method comprising the steps of:
- (a) providing an identifier to each data page, the identifier indicating when any of the data records contained therein were last modified;
- (b) selecting a data record from a data page;
- (c) copying the selected data record and the identifier of the data page to a second storage area;
- (d) verifying that the selected data record has not been modified since the time that it was copied to the second storage area based upon the stored identifier and a current identifier of the date page;
- and
- (e) executing the command.
A computer readable medium containing programming instructions for optimizing command execution in a database system, wherein data records are stored on a plurality of data pages therein, the programming instructions for:
- (a) providing an identifier to each data page, the identifier indicating when any of the data records contained therein were last modified;
- (b) selecting a data record from a data page;
- (c) copying the selected data record to a second storage area;
- (d) verifying that the selected data record has not been modified since the time that it was copied to the second storage area based upon the identifier;
- and
- (e) executing the command.
A relational database management system comprising:
- data records stored on a plurality of data pages;
- means for providing an identifier on each data page, the identifier indicating when any of the data records contained therein were last modified;
- means for selecting a data record from a data page;
- means for copying and storing the selected data record and the identifier from the data page to a second storage area;
- means for determining a current identifier from the data page;
- and
- means for verifying that the selected data record has not been modified since the time that it was copied to the second storage area by determining that the stored identifier is the same as the current identifier from the data page.
A method for optimizing command execution in a database system, wherein data records are stored on a plurality of data pages therein, the method comprising the steps of:
- (a) providing an identifier to each data page, the identifier indicating when any of the data records contained therein were last modified;
- (b) selecting a data record from a data page;
- (c) copying the selected data record and copying and storing the identifier to a second storage area;
- (d) verifying that the selected data record has not been modified since the time that it was copied to the second storage area based upon the identifier by:
- (d1) determining a current identifier for the data page;
- (d2) comparing the current identifier with the stored identifier, and
- (d3) concluding the selected data record has not been modified when the current identifier is the same as the stored identifier;
- and
- (e) executing the command.
A computer readable medium containing programming instructions for optimizing command execution in a database system, wherein data records are stored on a plurality of data pages therein, the programming instructions for:
- (a) providing an identifier to each data page, the identifier indicating when any of the data records contained therein were last modified;
- (b) selecting a data record from a data page;
- (c) copying the selected data record and copying and storing the identifier to a second storage area;
- (d) verifying that the selected data record has not been modified since the time that it was copied to the second storage area based upon the identifier by:
- (d1) determining a current identifier for the data page;
- (d2) comparing the current identifier with the stored identifier, and
- (d3) concluding the selected data record has not been modified when the current identifier is the same as the stored identifier;
- and
- (e) executing the command.
A relational database management system comprising:
- data records stored on a plurality of data pages;
- means for providing an identifier on each data page, the identifier indicating when any of the data records contained therein were last modified;
- means for selecting a data record from a data page;
- means for copying and storing the selected data record and the identifier from the data page to a second storage area;
- means for determining a current identifier from the data page;
- and
- means for verifying that the selected data record has not been modified since the time that it was copied to the second storage area by comparing the identifier stored in the second storage area with the current identifier, and concluding that the selected data record has not been modified if the stored identifier is the same as the current identifier.
Dependencies are inferred from the claim text.