Usage Notes
Consider the following when specifying File Open parameters:
Requirements – A File Open function is required when the Reqtype field of the pmiCmdBlock_t structure is pmiPIDMOpOpen.
BlkSize Value – The returned BlkSize value determines client buffering requirements. This value represents the maximum
block size that is sent to or received from an Access Module. On read operations,
record lengths greater than the BlkSize specification are considered an error condition that overwrites client memory. On
write operations, however, if the Teradata client utility needs to avoid spanned logical
records, the Access Module typically receives blocks that are smaller than the BlkSize specification.
BlkHeaderLen Value – The returned BlkHeaderLen value indicates the number of bytes at the beginning of each block returned on read
operations that are specific to an Access Module. If, for example, an Access Module
needs to prefix each record with a four‑byte block length, and that block length was
present at the beginning of the returned read buffer, then the BlkHeaderLen is set to 4. If, however, the Access Module does not include that field in its returned
data, then the BlkHeaderLen value is set to 0.