In addition to the bulk load data file, DataDirect Bulk Load can store bulk data in external overflow files. These overflow files are located in the same directory as the bulk load data file. Whether or not to use external overflow files is a performance consideration. For example, binary data is stored as hexadecimal-encoded character strings in the main bulk load data file, which increases the size of the file per unit of data stored. External files do not store binary data as hex character strings, and, therefore, require less space. On the other hand, more overhead is required to access external files than to access a single bulk load data file, so each bulk load situation must be considered individually.
The value of the Bulk Binary Threshold connection option determines the threshold, in KB, over which binary data is stored in external files instead of in the bulk load data file. Likewise, the Bulk Character Threshold connection option determines the threshold for character data.
In the case of an external character data file, the character set of the file is governed by the bulk load configuration file. If the bulk load data file is Unicode and the maximum character size of the source data is 1, then the data is stored in its source code page. See Character Set Conversions.
The file name of the external file contains the bulk load data file name, a six-digit number, and a ".lob" extension in the following format: CSVfilename_nnnnnn.lob. Increments start at 000001.lob.
