JDBC Type 4 Driver Programmer's Reference for SQL/MX Release 3.1 (H06.23+, J06.12+)

Architecture for LOB Support
The tables that support LOB data are:
Base table
Referenced by JDBC applications to insert, store, read, and update BLOB and CLOB data. In the base table, the Type 4 driver maps the
BLOB and CLOB columns into a data-locator column. The data-locator column points to the actual LOB data that is stored in a separate
user table called the LOB table.
LOB table
Actually contains the
BLOB and CLOB data in chunks. A Clob or Blob object is identified by a data locator. LOB tables have two formats:
LOB table for
BLOB data and a LOB table for CLOB data.
LOB Architecture: Tables for LOB Data Support
Types of LOB Table
The LOB table is a separate table from the base table that stores the LOB data. The two types of LOB table are: Binary or ASCII LOB and
Unicode LOB.
The Binary or ASCII LOB table structure is:
table_name CHAR(128) NOT NULL NOT DROPPABLE,
data_locator LARGEINT NOT NULL NOT DROPPABLE,
chunk_no INT NOT NULL NOT DROPPABLE,
lob_data VARCHAR(3880)
The Unicode LOB table structure for ASCII data is:
table_name CHAR(128),
data_locator LARGEINT,
chunk_no INTEGER,
lob_data VARCHAR(1955) CHARACTER SET UCS2
Setting Properties for the LOB Table
Specifying the LOB Table
Reserving Data Locators
Before running the JDBC application that uses BLOB and CLOB data through the JDBC API, the database administrator must create the LOB
tables. For information on creating LOB tables, see
Managing LOB Data with the Lob Admin Utility.
The JDBC applications that access BLOB or CLOB data must specify the associated LOB table names and, optionally, configure the
reserveDataLocators property.
Specifying the LOB Table
At run time, a user JDBC application notifies the Type 4 driver of the name or names of the LOB tables associated with the CLOB or BLOB
columns of the base tables being accessed by the application. One LOB table or separate tables can be used for BLOB and CLOB data.
The JDBC application specifies a LOB table name either through a system parameter or through a Java
Property object by using one of the
following properties, depending on the LOB column type:
LOB Column Type Property name
BLOB blobTableName