BUFFER
Default: operating system-dependent. See your Oracle operating system-specific
documentation to determine the default value for this parameter.
Specifies the size, in bytes, of the buffer used to fetch rows. As a result, this
parameter determines the maximum number of rows in an array fetched by Export.
Use the following formula to calculate the buffer size:

buffer_size = rows_in_array * maximum_row_size

If you specify zero, the Export utility fetches only one row at a time.
Tables with LONG, LOB, BFILE, REF, ROWID, LOGICAL ROWID, DATE, or type
columns are fetched one row at a time.

Note: The BUFFER parameter applies only to conventional path Export. It has
no effect on a direct path Export.

Example
This section shows an example of how to calculate buffer size.
Consider that the following table is created:
create table sample (name varchar(30), weight number);
The maximum size of the name column is 30, plus 2 bytes for the indicator. The
maximum size of the weight column is 22 (the size of the internal representation for
Oracle numbers), plus 2 bytes for the indicator.
Therefore, the maximum row size is 56 (30+2+22+2).
Export Parameters
To perform array operations for 100 rows, a buffer size of 5600 should be specified. :)