Types of Storage Structures
This chapter focuses on storage structures for traditional Ingres tables. For information on storage structures for X100 tables, see
X100 Table Structures and the chapter “Creating Indexes for X100 Tables.”
The types of storage structures for traditional Ingres tables 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 re-modification as the table grows. There is also a compressed ISAM structure (cISAM) with trailing blanks removed.
BTREE
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 Heap, Hash, ISAM, and BTree, 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.
Last modified date: 11/09/2022