Shared scans utilizing query monitor during query execution to improve buffer cache utilization across multi-stream query environments

A system for data base management, comprising:

• means for receiving a plurality of queries with respect to data in at least one of a plurality of tables in a database, wherein each table occupies at least one extent;
• means for reviewing each said query and determining a respective extents list of said extents containing said data needed by that said query;
• means for re-ordering said extents lists based on an order calculated to be more efficient for execution of said queries;
• means for loading said extents from said database as ordered in said extents lists into a buffer cache;
• and
• means for executing said queries on said data in respective said extents in said buffer cache to determine respective results.

A computer program, embodied on a computer readable storage medium, the computer program for executing in a computer having a database and comprising;

• a code segment that receives a plurality of queries with respect to data in at least one of a plurality of tables in a database, wherein each table occupies at least one extent;
• a code segment that reviews each said query and determines a respective extents list of said extents containing said data needed by that said query;
• a code segment that re-orders said extents lists based on an order calculated to be more efficient for execution of said queries;
• a code segment that loads said extents from said database as ordered in said extents lists into a buffer cache;
• and
• a code segment that executes said queries on said data in respective said extents in said buffer cache to determine respective results.