Use CONCATENATE when you want SQL*Loader to always combine the same number of physical records to form one logical record. In the following example, integer specifies the number of physical records to combine.
CONCATENATE integer
The integer value specified for CONCATENATE determines the number of physical record structures that SQL*Loader allocates for each row in the column array. In direct path loads, the default value for COLUMNARRAYROWS is large, so if you also specify a large value for CONCATENATE, then excessive memory allocation can occur. If this happens, you can improve performance by reducing the value of the COLUMNARRAYROWS parameter to lower the number of rows in a column array.