Data integrity

You can specify data integrity with the LO_HIGH_INTEG and LO_MODERATE_INTEG create flags, by calling the IfxLobDescriptor.setCreateFlags() method. For more information, see Set create flags.

An sbpage is the unit of allocation for smart large object data, which is stored in the user-data area of an sbspace. The structure of an sbpage in the sbspace determines how much data integrity the database server can provide. The database server uses the page header and trailer to detect incomplete writes and data corruption.

The database server supports the following levels of data integrity:
  • High integrity tells the database server to use both a page header and a page trailer in each sbpage.
  • Moderate integrity tells the database server to use only a page header in each sbpage.
Moderate integrity provides the following benefits:
  • It eliminates an additional data copy operation that is necessary when an sbpage has page headers and page trailers.
  • It preserves the user data alignments on pages because no page header and page trailer are present.
Moderate integrity might be useful for smart large objects that contain large amounts of audio or video data that is moved through the database server and that do not require a high data integrity. By default, the database server uses high integrity (page headers and page trailers) for sbspace pages. You can control the data integrity for a smart large object as part of its storage characteristics.
Important: Consider carefully whether to use moderate integrity for sbpages of a smart large object. Although moderate integrity takes less disk space per page, it also reduces the ability of the database server to recover information if disk errors occur.

For information about the structure of sbspace pages, see the HCL OneDB™ Administrator's Guide.