Using KSAM/XL and KSAM 64 (32650-90886)

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6 Writing and Updating Record Data
When records are written to a file for the first time, they are usually written sequentially.
Following execution of an FWRITE intrinsic, the logical record pointer is positioned at the
next sequential record in key sequence or at the end-of-file marker if the record is the last
in sequence.
Updating and deleting records also rely on pointer positioning. The logical and physical
record pointers are usually positioned by a read procedure, as discussed in Chapter 5 ,
“Reading File Data,”. Typically, a read procedure precedes an update or delete procedure to
verify that the correct record has been found. Table 6-1. specifies the advance flag and
pointer usage of each of the writing, updating, and deletion intrinsics.
Table 6-1. Pointer and Advance Flag Settings for Writing
Intrinsic Reads Advance
Flag
Sets Pointer Sets Advance Flag Pointer
Dependant
FREMOVE no both no yes
FUPDATE (keys
unchanged)
no none yes yes
FUPDATE(keys
changed)
no both no yes
FWRITE no both no yes