Although it's a bad practice, Oracle allows the columns to be named arbitrarily using the double-quote syntax. With this, the names can include keywords, lowercase or unicode characters.
A similar problem occurs when replicating to non-Oracle targets - some of the valid names in Oracle are keywords in other database systems and thus can cause issues for the APPLY process.
- For lowercase names: as the SQL is case insensitive and APPLY does not use double quotes, just create the column name in uppercase on the target
- For unicode: not supported
- For spaces in names: not supported (although spaces at the beginning or end of column names are ignored)
- For keywords: a global rename function is implemented. This APPLY_COLUMN_NAMES_MAP variable specifies a global rule renaming all columns in all replicated tables with a specified name to a different name.
set *.APPLY_COLUMN_NAMES_MAP coumn1=newcolumn1[,column2=newcolumn2[,...]]
set *.APPLY_COLUMN_NAMES_MAP COMMENT=COMMENT_COLUMN
APPLY process requires a restart to implement this mapping.
After restart, APPLY process log will show column mapping details as follow.
2016/06/06 05:34:37 INFO> Column translate: [COMMENT]=>[COMMENT_COLUMN]