DataLoader/MX Reference Manual (G06.24+)

DataLoader/MX Components
DataLoader/MX Reference Manual—525872-002
2-5
DataLoader/MX File System
•
Performance. DataLoader/MX efficiently uses the underlying OSS file system for
OSS files and also efficiently uses the underlying Enscribe file system for Guardian
files. Nowait I/O is used for everything except input from a terminal. For those
types of files that support it, multiple outstanding I/Os are maintained. Unstructured
disk files are processed with bulk I/O (56 KB blocks).
•
Text file line numbering. Whenever DataLoader/MX opens a Guardian EDIT file for
output, it automatically changes the line increment to .001, instead of to the default
increment of 1.000. Consequently, an empty text file can contain 100,000,000 lines
(.000, .001, .002, ..., 99999.999). The number and size of extents, as well as the
possible unavailability of such extents, can limit the number of lines, eventually
producing an error 43 or 45 (handled as described under the Full Files entry).
•
$RECEIVE. You can specify $RECEIVE like any other file for either input or output.
DataLoader/MX matches writes to the DataLoader/MX process from another
process with reads of $RECEIVE from within DataLoader/MX and reads of the
Table 2-1. DataLoader/MX I/O Blocking Behavior
Max.
Block
Size
BLKSIZE
Modifier
Allowed?
Max.
Rec
Length
RECFORM=
FB
Allowed?
RECFORM=
VB
Allowed?
RECFORM=
IBMVB
Allowed?
EDIT file N.A.
1
No239NoNoNo
EDIT file
with CSV
N.A.
1
No 4072 if
input
No No No
Process 32000 No 32000 Yes
3
Yes
5
No
$RECEIVE 32000 No 32000 Yes
3
Yes
5
Yes
6
Structured
File
N.A.
1
No 4072 No No No
Tape 32767 No 32767 Yes
3
Yes
5
Yes
6
Terminal N.A. No 37555 No No No
Unstructured
File
57344 Yes
2
57344 Yes
4
Yes
5
Yes
6
1 The blocking is done by file system functions.
2 The specified size must be an integral multiple of 2048 between 2048 and 57344.
3 DataLoader/MX performs I/O blocking based on the criteria specified. For output, DataLoader/MX chooses the
block size to be an integral multiple of the record size that will hold as many records as possible but not exceed
the value shown in the Max Block Size column in this table. For input, DataLoader/MX unblocks the data into fixed
length records. A file will not contain a partial record.
4 A record transparently spans the block if the block size is not an integral multiple of the record size.
5 The block size chosen is the value shown in the Max Block Size column in this table unless otherwise specified
in the BLKSIZE modifier for the unstructured file. Blocks contain an integral number of records. If the block size is
not a multiple of the record size, the block is padded to the full length. For more information, see VARIN and
VAROUT in the File Utility Program (FUP) Reference Manual.
6 For input only.
Note. In the OSS environment, you must precede the $ with a backslash (for example,
\$RECEIVE).