IOT Overview
An index-organized table is a b-tree index structure that acts like a table. All the data is stored within the b-tree structure or in an overflow tablespace. Listing 13.1 illustrates the basic syntax for an IOT. Notice everything is pretty much the same, down to the organization index clause. This tells Oracle that this is an IOT. The pctthreshold tells Oracle to store the remainder of the row in the defined overflow tablespace if a row is larger than this percentage of the block size. This ensures that multiple key values exist in each index block. If the b-tree index block contains only a few rows, it would be more efficient not to have an index, defeating the purpose of an index—fast access to rows.
The advantage, in regards to ...
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