Using Smart Large Objects

To store columns of a BLOB or CLOB data type, you must allocate an sbspace. An sbspace is a logical storage unit that stores BLOB and CLOB data in the most efficient way possible. You can write IBM Informix ESQL/C programs that allow users to fetch and store BLOB or CLOB data. Application programmers who want to access and manipulate smart large objects directly can consult the IBM Informix: ESQL/C Programmer's Manual.

In any SQL statement, interactive or programmed, a BLOB or CLOB column cannot be used in the following ways:

• In arithmetic or Boolean expressions
• In a GROUP BY or ORDER BY clause
• In a UNIQUE test
• For indexing, as part of an Informix B-tree index

  However, DataBlade developers have the capability to create indexes on CLOB columns.

In a SELECT statement entered interactively, a BLOB or CLOB column can:

• Specify null values as a default when you create a table with the DEFAULT NULL clause
• Disallow null values using the NOT NULL constraint when you create a table
• Be tested with the IS [NOT] NULL predicate

From an ESQL/C program, you can use the ifx_lo_stat() function to determine the length of BLOB or CLOB data.