2 Persistent LOBs

A persistent LOB is a LOB instance that exists in a table row in the database. Persistent LOBs can be stored as SecureFiles or BasicFiles.

The term LOB can represent LOBs of either SecureFiles or BasicFiles type, unless the storage type is explicitly indicated. It can be either by name for both storage types, or by reference to archiving or linking, which only applies to the SecureFiles storage type. Oracle strongly recommends SecureFiles for storing and managing LOBs.

SecureFiles LOB storage is the default in the CREATE TABLE statement, if no storage type is explicitly specified. All new LOB columns use SecureFiles LOB storage by default, which is the recommended method for storing and managing LOBs. SecureFiles LOB storage is designed to provide great performance and scalability to meet or exceed the performance of traditional network file system. However, you must use BasicFiles LOB storage for LOB storage in tablespaces that are not managed with Automatic Segment Space Management (ASSM). SecureFiles LOBs can only be created in tablespaces managed with Automatic Segment Space Management (ASSM).

• Creating a Table with LOB Columns
  You can use the CREATE TABLE statement or an ALTER TABLE ADD column statement to create a new LOB column. This section introduces basic DDL operations on LOBs to get you started quickly.
• Inserting and Updating LOB Values in Tables
  Oracle Database provides various methods to insert and update the data available in LOB columns of database tables.
• Selecting LOB Values from Tables
  You can select a LOB into a Character Buffer, a RAW Buffer, or a LOB variable for performing read and write operations.
• Performing DML and Query Operations on LOBs in Nested Tables
  This section describes the INSERT, UPDATE, and SELECT operations on LOBs in Nested Tables. To update LOBs in a nested table, you must lock the row containing the LOB explicitly.
• Performing Parallel DDL, Parallel DML (PDML), and Parallel Query (PQ) Operations on LOBs
  Oracle supports parallel execution of the following operations when performed on partitioned tables with SecureFiles LOBs or BasicFiles LOBs.
• Sharding with LOBs
  LOBs can be used in a sharded environment. This section discusses the interfaces to support LOBs in sharded tables.