Types of Storage Structures
The types of storage structures are summarized here:
Heap
The non-keyed storage structure with sequential data entry and access. There is also a compressed heap structure (cheap) with trailing blanks removed.
Hash
A keyed storage structure with algorithmically chosen addresses based on key data values. There is also a compressed hash structure (chash) with trailing blanks removed.
ISAM
A keyed storage structure in which data is sorted by values in key columns for fast access. The index is static and needs remodification as the table grows. There is also a compressed ISAM structure (cISAM) with trailing blanks removed.
B-tree
A keyed storage structure in which data is sorted by values in key columns, but the index is dynamic and grows as the table grows. There is also a compressed B-tree structure (cB-tree) with trailing blanks removed.
For more information on the compressed structure for each of the above types, see the chapter “Maintaining Storage Structures.”
Another storage structure, R-tree, can be used only on secondary indexes, as described in
R-tree Secondary Index (see page
R-tree Secondary Index).