DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

6.3 LOAD and UNLOAD delimited input and output
In V7, the LOAD utility input file is required to be of positional format. If you want to move data
to DB2 for z/OS, you must write a program to convert the data into the positional format that
the LOAD utility can understand, or use INSERT statements, thereby not exploiting the
performance advantage that the LOAD utility offers for a large amount of data.
In DB2 V8, the LOAD utility is enhanced to accept data from a delimited file. The UNLOAD
utility is also enhanced to produce a delimited file when unloading the data. These
enhancements help to simplify the process of moving or migrating data into and out of DB2
for z/OS.
Reformatting data for DB2 (before V8)
Reformatting data for DB2 is a very time consuming procedure. Prior to DB2 V8, you can load
data only from an input flat file, either a partitioned data set or a regular flat file. The file must
include length information for those fields that become VARCHAR columns in a DB2 table.
Reformatting the data for DB2 means adding 2 bytes of binary data to the beginning of such a
field. These 2 bytes contain a binary number representing the length of the data within the
field. The following steps were needed to reformat data for DB2 for z/OS.
1. Unload the data from a table residing on another relational database and transmit the file
to z/OS and store it (either as member in a PDS, or as a sequential file).
2. Write a program, possibly using REXX, to determine the length of the variable character
data and generate the 2 byte binary length fields. Also the program should output a file
with the positions and length of the fields which can be useful to set up LOAD utility
statements.
3. Prepare for a input control file used for a program, describing where is the beginning of
each field and what kind of data will be encountered in input file records.
4. Run the program, input the data from the other RDBMS and the input control file.
5. Setup the LOAD utility control statement using the output of the program and specifying
the generated input data in INDDN in the JCL statement, and then run the LOAD utility to
load data into DB2. See Example 6-2 for an example of the LOAD statement.
Example 6-2 Sample LOAD statement
LOAD DATA INDDN(CPRSRECS) LOG NO RESUME YES
INTO TABLE PAOLOR2.DATA_TYPE
(DATA_TYPE POSITIN(1) VARCHAR,
DESCRIPTION POSITION(9) VARCHAR)
Delimited file input and output
In V8, the LOAD utility accepts a delimited file, and the UNLOAD utility can produce a
delimited file. Most relational databases including DB2 on Linux, UNIX, Windows, Oracle®
and Sybase can unload data in delimited format, where each record is a row, and columns
are separated by commas, for example. So this enhancement eases dramatically the import
or export of a large amount of data from other operating system platforms to DB2 for z/OS
and vice versa. And also this eliminates the requirement to write a program to convert
non-z/OS platform data into positional format for the LOAD utility, so you can avoid the data
reformatting process described above.
For instance, if you want to move data from a spreadsheet from a Windows workstation to
DB2 for z/OS, you need to take the following steps:
► Save the spreadsheet data in comma separated value (CSV) format
270 DB2 UDB for z/OS Version 8 Performance Topics