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DB Performance: Early DB2 & M204<br />
DB2 Query Indexes were explained in 1979 paper 1<br />
<br />
<br />
<br />
<br />
Rather primitive: Choose single column restriction that gives<br />
smallest “selectivity factor” F<br />
Selectivity factor was later “Filter Factor” in documentation<br />
The ability to AND Filter Factors waited until DB2 V2, 1988<br />
After DB2 was introduced, Pat was working at CCA, which sold<br />
a DBMS called Model 204 (M204) with efficient bitmap indexing<br />
Pat published a paper called “The Set Query Benchmark” 2 that<br />
compared M204 query performance to that of DB2 on MVS<br />
Lucky that DB2 allowed this: DBMS products today would sue<br />
1 P.G. Selinger et al., Access Path Selection in a relational database management system.<br />
SIGMOD 1979; 2 P. O'Neil. The Set Query Benchmark. Chapter 6 in The Benchmark Handbook for<br />
Database and Transaction Processing Systems. (1st Edition, 1989, 2nd Ed., 1993)<br />
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