Row compression is a form of logical data compression in which Teradata Database stores a repeating column value set only once, while any non-repeating column values that belong to that set are stored as logical segmental extensions of the base repeating set. Row compression is a lossless method.
Like multivalue compression, there is no decompression necessary to access row compressed data values. For an explanation of row compression, see “CREATE JOIN INDEX” in SQL Data Definition Language Detailed Topics.
You control the row compression of join indexes with the syntax you use when you create an index (see “CREATE JOIN INDEX” in SQL Data Definition Language). The row compression of hash indexes is automatic and requires no special syntax.