Administrative API Reference

Long Field Manager Log Records

Long field manager log records are written only if a database is configured with LOG RETAIN on or USEREXITS enabled. They are written whenever long field data is inserted, deleted, or updated.

To conserve log space, long field data inserted into tables is not logged if the database is configured for circular logging. In addition, when a long field value is updated, the before image is shadowed and not logged.

All long field manager log records begin with a header.

All long field manager log record offsets are from the end of the log manager log record header.

When a table has been altered to capture LONG VARCHAR OR LONG VARGRAPHIC columns (by specifying INCLUDE LONGVAR COLUMNS on the ALTER TABLE statement):

The long field manager will write the appropriate long field log record.
When long field data is updated, the update is treated as a delete of the old long field value, followed by an insert of the new value.
When tables with long field columns are updated, but the long field columns themselves are not updated, a Non-update Long Field Record is written.
The Delete Long Field Record and the Non-update Long Field Record are information only log records.

Table 108. Long Field Manager Log Record Header (LongFieldLogRecordHeader)

Description Type Offset (Bytes)
Originator code (component identifier = 3) unsigned char 0(1)
Operation type^a unsigned char 1(1)
Pool identifier unsigned short 2(2)
Object identifier unsigned short 4(2)
Parent pool identifier^b unsigned short 6(2)
Parent object identifier^c unsigned short 8(2)
Total Length: 10 bytes

Note:

^a Valid operation type values and definitions:
Operation type value Long Field Log Record Type 110 Add Long Field Record 111 Delete Long Field Record 112 Non-Update Long Field Record

^b Pool ID of the data object
^c Object ID of the data object

Add/Delete/Non-update Long Field Record

These log records are written whenever long field data is inserted, deleted, or updated. The length of the data is rounded up to the next 512-byte boundary.

Table 109. Add/Delete/Non-update Long Field Record Log Record Structure

Description Type Offset (Bytes)
Log header LongFieldLogRecordHeader 0(10)
Long field length^a unsigned short 10(2)
File offset^b unsigned long 12(4)
Long field data char[ ] 16(variable)

Note:

^a Long field data length in 512-byte sectors (actual data length is not logged). The value of this field is always positive. The long field manager never writes log records for zero length long field data that is being inserted, deleted, or updated.
^b 512-byte sector offset into long field object where data is to be located.

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