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Definition and Characteristics

Definition

An External LOB type is data to process Large Object, such as text or images. When LOB-type data is created and inserted, it will be stored in a file to an external storage, and the location information of the relevant file (LOB Locator) will be stored in the CUBRID database. If the LOB Locator is deleted from the database, the relevant file that was stored in the external storage will be deleted as well. CUBRID supports the following two types of LOB:

  • Binary Large Object (BLOB)
  • Character Large Object (CLOB)
Related Terms
  • LOB (Large Object) : Large-sized objects such as binaries or text.
  • FBO (File Based Object) : An object that stores data of the database in an external file.
  • External LOB: An object better known as FBO, which stores LOB data in a file into an external DB. It is supported by CUBRID. Internal LOB is an object that stores LOB data inside the DB.
  • External Storage: An external storage to store LOB (example : POSIX file system).
  • LOB Locator: The path name of a file stored in external storage.
  • LOB Data: Details of a file in a specific location of LOB Locator.
File Names

When storing LOB data in external storage, the following naming convention will be applied:

{table_name}_{unique_name}

  • table_name: It is inserted as a prefix and able to store the LOB data of many tables in one external storage.
  • unique_name: The random name created by the DB server.
Default Storage
  • LOB data is stored in the local file system of the DB server. LOB data is stored in the path specified in the -lob-base-path option value of cubrid createdb; if this value is omitted, the data will be stored in the [db-vol path]/lob path where the database volume will be created. For more details, see Database Creation and Storage Creation and Management.
  • If the relevant path is deleted despite a LOB data file path being registered in the database location file (databases.txt), please note that the utility that operates in database server (cub_server) and standalone will not function normally.