System and method for performing database operations and for skipping over tuples locked in an incompatible mode

A method of processing a stream of data in a database management system, in accordance with a query, the query specifying a defined range of rows in a database table to be accessed, the method comprising:

• performing an initial scan to access the defined range of rows in the database table;
• while performing the initial scan,
• building a list of rows that are added to the database table during the initial scan and that are to be accessed by the scan operator after the initial scan;
• skipping over rows, if any, locked in conflicting modes, the conflicting modes preventing access to the locked rows;
• and
• adding to the list of rows the locked rows skipped during the initial scan;
• performing a secondary scan to access rows in the list, including accessing the rows in the list that are not locked in the conflicting modes;
• and
• while performing the secondary scan, adding to the list of rows additional rows added to the database table after the initial scan.

A database management system, comprising:

• a query execution module for executing a specified query, the query execution module including a table access operator for accessing a defined range of rows in a specified one of the database tables;
• the table access operator including executable instructions for:
• performing an initial scan to access the defined range of rows in the database table;
• while performing the initial scan,
• building a list of rows that are added to the database table during the initial scan and that are to be accessed by the scan operator after the initial scan;
• skipping over rows, if any, locked in conflicting modes, the conflicting modes preventing access to the locked rows;
• and
• adding to the list of rows the locked rows skipped during the initial scan;
• performing a secondary scan to access rows in the list, including accessing the rows in the list that are not locked in the conflicting modes;
• and
• while performing the secondary scan, adding to the list of rows additional rows added to the database table after the initial scan.

A computer program product for use in conjunction with a computer system, the computer system including a database, including a plurality of tables, each table storing data in one or more rows;

• the computer program product comprising a computer readable storage medium and a computer program mechanism embedded therein, the computer program mechanism comprising:
• a query execution module for executing a specified query, the query execution module including a table access operator for accessing a defined range of row s in a specified one of the database tables;
• the table access operator including instructions for responding to a request, received from a calling application by returning to the calling application qualifying rows, if any, from the database table;
• the table access operator further including instructions for skipping over rows, if any, locked in conflicting modes, the conflicting modes preventing access to the locked rows.

A computer program product for use in conjunction with a computer system, the computer system including a database, including a plurality of tables, each table storing data in one or more rows;

• the computer program product comprising a computer readable storage medium and a computer program mechanism embedded therein, the computer program mechanism comprising:
• a query execution module for executing a specified query, the query execution module including a table access operator for accessing a defined range of rows in a specified one of the database tables;
• the table access operator including executable instructions for:
• performing an initial scan to access the defined range of rows in the database table;
• while performing the initial scan,
• building a list of rows that are added to the database table during the initial scan and that are to be accessed by the scan operator after the initial scan;
• skipping over rows, if any, locked in conflicting modes, the conflicting modes preventing access to the locked rows;
• and
• adding to the list of rows the locked rows skipped during the initial scan;
• performing a secondary scan to access rows in the list, including accessing the rows in the list that are not locked in the conflicting modes;
• and
• while performing the secondary scan, adding to the list of rows additional rows added to the database table after the initial scan.