This option
improves performance by specifying a number of rows that can be held
in memory for input into SAS. Buffering data reads can decrease network
activities and increase performance. However, because SAS stores
the rows in memory, higher values for READBUFF= use more memory.
In addition, if too many rows are selected at once, then the rows
that are returned to the SAS application might be out of date. For
example, if someone else modifies the rows, you do not see the changes.
When READBUFF=1,
only one row is retrieved at a time. The higher the value for READBUFF=,
the more rows are retrieved in one fetch operation. If READBUFF= is
not set, certain operations such as SQL SELECT statements cause the
number of rows to be set to the client's default value, which for
the LIBNAME engine is one row at a time. Setting READBUFF=128 can
significantly boost the application's performance.
If you
do not specify a value with this option, the engine calculates the
buffer size based on the row length of your data (with a minimum of
10) and retrieves the number of rows in each fetch operation.