Proactive Index Design - Relational Database Index Design and the Optimizers - page 76

C

LNAME FNAME BORN CITY

JONA MARIA 1919 KRANJ

T T

JONES ADAM 1944 LONDON

T

JONES ADAM 1950 BERN
JONES ADAM 1953 OSLO

T

T

T

JONES ADAM 1954 LONDON

T

JONES AXEL 1899 MIAMI

JONES BETTY 1971 GRAZ

1,000,000
table rows

1,000,000 index rows

Figure 5.6 Clustering index with skip-sequential table access.

P,C U

LNAME,
FNAME

CNO PNO

CUST

Figure 5.7 Cheapest
adequate index or best
possible index: Example 1A.

1,000,000 rows

may use the two techniques (BQ and QUBE) in the whole index design approach
discussed in Chapter 4.
Figure 5.7 shows the current indexes for the customer table. The user chooses
both the last name (LNAME) and the city name (CITY) from pop-up windows
before starting the transaction, which then opens CURSOR55 (refer to SQL 5.5).
The only index that appears to be useful is the index (LNAME, FNAME).
We will analyze the use of this index with the cursor to determine whether
performance will be adequate.