sqlalchemy server_defaults end up as defaults in the database when new values are inserted.
t = Table( "test", metadata_obj, Column("abc", String(20), server_default="abc"), Column("created_at", DateTime, server_default=func.sysdate()), Column("index_value", Integer, server_default=text("0")), )
CREATE TABLE test ( abc varchar(20) default 'abc', created_at datetime default sysdate, index_value integer default 0 )