4-54 IBM Informix OnLine Database Server Administrator’s Guide
Description of Migration Methods
Description of Migration Methods
This section provides an overview of how each data migration method
works.Figure 4-10 on page 4-56illustrates the four migration methods. This
section does not attempt to compare the methods. Comparisons and
contrasts begin onpage 4-57.
Refer toChapter 7, “Utilities,” for a complete discussion of each OnLine
utility. TheLOAD and UNLOAD statements are documented theDB-Access
User’sManual.

UNLOAD/dbschema/LOAD

TheDB-Access UNLOAD statement writes the rows retrieved in a SELECT
statement to a delimited ASCII file. A parameter in the UNLOAD statement
enables you to specify a field-delimiting character for theASCII file. The
UNLOAD statement creates the ASCII input file of migration data.
The database server utilitydbschema writes the SQL statements needed to
replicate the specified database or table to an ASCII file. Thedbschema
output file can be modified with a system editor or run as is to create the
database or table that will receive the migration data.
TheDB-Access LOAD statement inserts data from one or more of the
delimitedASCII input files created by UNLOAD into one or more tables
created from adbschema output file.

UNLOAD/dbschema/dbload

TheUNLOAD statement and dbschema utility perform the same preparation
tasks in this method as described in the preceding paragraph. The database
serverutility dbload takes one or more ASCII input files created by UNLOAD
and inserts the data into one or more specified tables created from a
dbschema output file. Thedbload utility inserts the data as directed by a
command file that is created by the user. The user can specify additional
instructions at the command line whendbload is executed.