The question is a bit short but I cured a locking problem with the following if it helps?
-- MESSAGE "Data" OR "Information" "is out of date" on some APP screens.
--
-- Identify which table is affected. In this case we know that
-- ops are stored in table WTL. We now need a session_id and serial number
-- so we can invoke the kill command against this rogue process.
--
-- sqlplus system/password@schemaname
select object_id from dba_objects where object_name ='WTL';
--3738
--3820
--3930
--3335
--
-- The following was run against 3738, 3820 and 3930 but nothing was returned
-- However when run against 3335 returned a session_id of 71
select * from v$locked_object where object_id=3335;
-- All we need now is the serial number so we can kill the rogue process.
--
select sid, serial#, command, taddr from v$session where sid=71;
--
-- This returned us a serial number 16711
--
-- All the above can be combined as below:
--
select sid, serial#, command, taddr
from v$session
where sid=(select SESSION_ID
from v$locked_object
where object_id in (select object_id
from dba_objects
where object_name='WTL'))
-- If we are sure this is the rogue lock then kill it.
alter system kill session '71,16711';
-- If it refuses to die use
alter system kill session '71,16711' IMMEDIATE ;
--
-- NOTE: Your sid and serial number will be different from this example!
-- NOTE: Closing the APP window and waiting 10 minutes can (sometimes) also cure the fault.
tablespace,segment,extent,oracle blocks.. are the logical schema of a database
A database schema is described in a formal language supported by the database management system (DBMS). In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables. Schemas are generally stored in a data dictionary. Although a schema is defined in text database language, the term is often used to refer to a graphical depiction of the database structure Levels of database schema 1. Conceptual schema, a map of concepts and their relationships 2. Logical schema, a map of entities and their attributes and relations 3. Physical schema, a particular implementation of a logical schema 4. Schema object, Oracle database object 5. Schema is the over all structure of the database
the schema can be termed either conceptual or logical or physical. But mostly speaking, the term schema is used to refer to a logical structure.
Database schema are the logical structure of entities (tables or object classes) and their relationships (keys, or object associations) in a database. Schema can exist at different levels of abstraction (see: en.wikipedia.org/wiki/Database_schema). Schema themselves may or may not exist as such in a database. In general schema at the higher levels of abstraction are design models that are captured in printed documents, and authored by business analysts and database designers, rather than created by database programmers and stored in the database itself. But in some types of databases, schema at any level of abstaction can be realized physically. In Oracle databases, schema can be realized as schema objects, which are a part of an Oracle database. These schema objects may represent a human user's conceptual model of the knowledge captured in an enterprise database. Thus defined, there can be many schema that can be associated with one physical database. In other kinds of relational database, an abstract user's schema can be represented by logically linked metadata, views, and stored procedures assocated with a user class. In object-oriented databases, especially those based on the highly self-referential language Smalltalk (e.g. Gemstone/S), schema are realized as "physical" objects in the database as a matter of course, as well as in the logical models captured in design documents. The schema objects in such databases are, in essence, the classes comprising the infrastructure of the database or application. Oracle-style user schema are readily created; these would be realized as user interface orchestrator classes.
A user in Oracle corresponds to a schema. Objects, such as table and indexes, must exist within a schema. Without creating a user/schema, use of the database will be limited to the built-in schemas and objects, such as the one-row DUAL table and standard PL/SQL packages.
Well, darling, in Oracle, a user is an account used to log in and access the database, while a schema is a collection of database objects (tables, views, etc.) associated with a particular user. So, think of a user as the key to the front door, and a schema as the fancy furniture and decor inside the house. You can have multiple schemas in a single user account, just like you can have multiple rooms in a house. Easy peasy lemon squeezy!
We know that schema in the database is refer to the basic design of that database and is stored in an object . That object is known as schema object of database.
Oracle is relational DataBase
The Star & Snowflake are two common type of database Schema.
One can easily read a database schema through any software available currently. Simpy because a database schema is a blueprint which can be read by a software.
A database schema is an actual plan for a database system. Sub-schemas are separate divisions that are used to achieve the plan for the database system.
Oracle is one of the popular database and DBA (DataBase Administrator) is the person who maintain the database (install oracle software, create,setup,maintain database)