Number of distinct values

Specifies the number of distinct key values expected for this index.

The entry size of the vector of an EVI has a direct affect on the size and performance of the index. An index with a 4 byte vector entry size consumes 4 times as much space as the same index with a 1 byte vector. Also, the scanning time during query processing of a 4 byte vector entry size EVI may be 4 times that of the same EVI with a 1 byte vector entry size.

Not specified: The number of distinct key values is not specified.

1 to 255: Specifying a number between 1 and 255 for an EVI allocates a vector with a 1 byte entry for each row in the table. An encoded vector index with a 1 byte vector entry length restricts the maximum number of distinct key values that the index can contain to 255.

256 to 65355: Specifying a number between 256 and 65355 for an EVI allocates a vector with a 2 byte entry for each row in the table. An encoded vector index with a 2 byte vector entry length restricts the maximum number of distinct key values that the index can contain to 65355.

Greater than 65356Specifying a number greater than 65356 for an EVI allocates a vector with a 4 byte entry for each row in the table. An encoded vector index with a 4 byte vector entry length restricts the maximum number of distinct key values that the index can contain to 2147483647.

For non-EVIs:

Specifies the estimated number of rows the table will contain. This value does not have to be exact, but may be helpful to the query optimizer.