Is the Oracle_SID the same the login name on Oracle?
Your colleague is right. A schema and a user are pretty much the same in Oracle. When you create a user, a schema with the same name is automatically created.
A schema is a collection of logical structures of data, or schema objects. A schema is owned by a database user and has the same name as that user. Each user owns a single schema
There is no concept of a "database" the way there is in Sybase or SQL Server.
The SID is the identifier for an instance which is something completely different.
A fully qualified table name in Oracle only consists of two elements: the schema (=owner) and the object name: schema_name.table_name and they are separated by a single .
My question is: Is the Oracle_SID the same the login name on Oracle?
The answer to that is: NO, absolutely not
The Oracle System ID (SID) is used to uniquely identify a particular database on a system. For this reason, one cannot have more than one database with the same SID on a computer system.When using RAC, all instances belonging to the same database must have unique SID's.
A schema is a collection of logical structures of data, or schema objects. A schema is owned by a database user and has the same name as that user. Each user owns a single schema.
refer http://docs.oracle.com/cd/B19306_01/server.102/b14220/schema.htm
you may find the difference between schema vs user
https://dba.stackexchange.com/questions/37012/difference-between-database-vs-user-vs-schema
Oracle SID is beside the point of login name. SID is the identifier of Oracle instance.
Oracle historically considers SCHEMA, ROLE and USER as a very close terms and has common implementation for them. For example, you can create something using command CREATE USER and then drop it using command DROP SCHEMA.