It may be possible that some changes happen to table structure on target side, but this affects the replicat process.
For example, if a column name is changed in the replicat side itself and the primary column name is different then the replicat process will abended with error "invalid identifier"
In those cases, defgen utility will help to handle the column name changes.
Not only the above case, when you have structural changes between tables defgen utility can be used to create a COLMAP information.
First lets create a DDL information using defgen utility on source side.
## Create a Defgen Parameter file
EDIT PARAMS defgen
DEFSFILE I:\ggs_source\dirsql\def.sql
USERID ggs_owner, PASSWORD ggs_owner
TABLE test.myobj;
## Using Defgen utitlty create the sql file
./defgen paramfile I:\ggs_source\dirprm\defgen.prm
## Copy the generated SQL file to target location
scp I:\ggs_source\dirsql\def.sql 192.168.56.109:/u01/ggt_target/dirsql/def.sql
On target side, Edit the Replicat parameter file to colmap the differences in column names
./ggsci
EDIT params rep2
##Edit and Add the Bold part of following lines to parameter file
REPLICAT rep2
SOURCEDEFS /u01/ggt_target/dirsql/def.sql
USERID ggs_owner, PASSWORD ggs_owner
MAP test.myobj, TARGET test.myobj, COLMAP (usedefaults,object_name=objname);
## Start the replicat
start replicat rep2
## Replication will proceed with out error
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