> I want to add keywords in psql (it is not function or operation)
> Let me know what source files must to be modified.
gram.y, keywords.c just to get the keyword recognized by the parser.
Some other files in src/backend/parser/ will need to be changed if the
new keywords don't map to existing functionality, and of course other
files in the optimizer/executor would need to be changed to support new
capabilities.
Good luck!
- Tom