Reload Analyzer Manual

Tandem Reload Analyzer Manual Page 20 of 42
Figure 1-2. An Organized File
The data blocks are both physically and logically contiguous on disk. The next pointer
from each data block points to the adjacent data block. In Figure 1-2, the dashed lines
with arrowheads point from the block to its adjacent block. The next and previous
pointers are the only differences between Figure 1-2 and Figure 1-1.
Note that the records within the data and index blocks are in logical order by the
primary record key. In this example, the first name is the primary record key. The first
primary record key in the second data block comes logically after the last record in the
first data block. The first primary record of the third block also follows the second block.
The index and data blocks have a uniform amount of empty space and number of
records. Each data block shown has three records. The file also has the fewest
possible index levels. This file has a root index level and only one index level below the
root index. Looking at the disorganized file (Figure 1-3), you will see that the file has
more than one index level below the root index.