Control of where smart large object data is stored

You specify the data type of a column when you create the table.

For smart large objects, you specify CLOB, BLOB, or user-defined data types. As the following figure shows, to control the placement of smart large objects, you can use the IN sbspace option in the PUT clause of the CREATE TABLE statement.
Figure 1. Control smart-large-object placement
This figure shows that you use the onspaces -c -S command to create a dbspace named s9_sbspc. The figure also contains this SQL: CREATE TABLE catalog (…advert_descr CLUB, …) …PUT advert_descr IN s9_sbspc.

Before you specify an sbspace in a PUT clause, you must first create the sbspace. For more information about how to create an sbspace with the onspaces -c -S command, see Adding a chunk to a dbspace or blobspace. For more information about how to specify smart large object characteristics in the PUT clause, see the CREATE TABLE statement in the IBM® Informix® Guide to SQL: Syntax.

If you do not specify the PUT clause, the database server stores the smart large objects in the default sbspace that you specify in the SBSPACENAME configuration parameter. For more information about SBSPACENAME, see the configuration parameter topics of the HCL Informix Administrator's Reference.

An sbspace includes one or more chunks, as the following figure shows. When an sbspace contains more than one chunk, you cannot specify the chunk in which the data is located.

You can add more chunks at any time. It is a high-priority task of a database server administrator to monitor sbspace chunks for fullness and to anticipate the necessity to allocate more chunks to an sbspace. For more information about monitoring sbspaces, see your HCL Informix Performance Guide.
Figure 2. Sbspaces that link logical and physical units of storage
This figure shows a dbspace that includes one chunk and an sbspace that includes two chunks.

The database server uses sbspaces to store table columns that contain smart large objects. The database server uses dbspaces to store the rest of the table columns.

You can mirror an sbspace to speed recovery in event of a media failure. For more information, see Mirroring.

For information about using onspaces to perform the following tasks, see Manage disk space.
  • Creating an sbspace
  • Adding a chunk to an sbspace
  • Altering storage characteristics of smart large objects
  • Creating a temporary sbspace
  • Dropping an sbspace

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