How does one prevent table space fragmentation

Always set PCTINCREASE to 0 or 100.

Bizarre values for PCTINCREASE will contribute to fragmentation.

For example if you set PCTINCREASE to 1 you will see that your extents are going to have weird and wacky sizes: 100K, 100K, 101K, 102K etc.

Such extents of bizarre size are rarely re – used in their entirety.

PCTINCREASE of 0 or 100 gives you nice round extent sizes that can easily be reused.

Example: .100K, 100K, 200K, 400K etc.

Note that the number of extents per segment does not cause any performance issue anymore, unless they run into thousands and thousands where additional I/O may be required to fetch the additional blocks where extent maps of the segment are stored.