Dataloader/MP Reference Manual

DataLoader/MP Components
DataLoader/MP Reference Manual—424148-003
2-5
DataLoader/MP File System
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Edit file line numbering. Whenever DataLoader/MP opens an edit file for output, it
automatically changes the line increment to. 001, instead of to the default
increment of 1.000. Consequently an empty edit 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 could limit the number of lines, eventually
producing an error 43 or 45 (handled as described under “Full Files”).
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$RECEIVE. You can specify $RECEIVE like any other file for either input or output.
DataLoader/MP matches writes to the DataLoader/MP process from another
process with reads of $RECEIVE from within DataLoader/MP and reads of the
DataLoader/MP process from another process to writes to $RECEIVE. You can
use $RECEIVE as input and output at the same time.
This ability to use $RECEIVE as a normal input or output file is useful when you
use other utilities. For example, you can process an SQL table in its binary form by
using the SQLCI COPY command to copy the table to or from a named
DataLoader/MP process. You can also receive data from FTP directly into
DataLoader/MP without having to put it to a disk file first. You can do this by having
the FTP client get a file to a named DataLoader/MP process.
When you run DataLoader/MP with $RECEIVE as its output, use the -S parameter
to tell DataLoader/MP to generate statistics that include information about the
buffer pool. These statistics are useful for building your loading application and
deciding how many DataLoader/MP processes to use.
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Opening nonexistent processes. DataLoader/MP is often used in an environment
where a number of processes, such as DataLoader/MP and SQLUTIL processes,
are communicating with each other. In such an environment, processes being
opened must exist before processes that open them. To simplify this, the
DataLoader/MP file system delays an open when the process being opened does
not exist yet. If an open returns error 14, the file system delays for one second and
retries the open. It will repeat this 60 times for a total of a one minute delay before
reporting an error on the open. You can specify a larger or smaller wait time using
the WAIT modifier.
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Opening busy files. DataLoader/MP is used in environments where many
processes are started by TACL, some started waited fashion and some nowaited.
In this environment, TACL can start a process before work needed from a second
process has completed. To eliminate any problems associated with this,
DataLoader/MP uses the delaying strategy described under the previous item
whenever an open yields error 12.
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Speed inhibitors. Some types of files can have attributes that reduce access speed
to the files. DataLoader/MP checks for these situations and, if present, reports a
warning message and continues processing:
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Unbuffered output disk files
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Output disk files with the REFRESHEOF attribute
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Output disk files on mirrored disks with the SERIALWRITES attribute