Kbase 11428: How CRC is calculated in Version 7
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
How CRC is calculated in Version 7
FIELDS USED IN V7 CRC CALCULATION:
_Sequence file:
_Seq-Name
_Cycle_OK
_Seq-Min
_Seq-Max
_Seq-Incr
_File file:
_File-Name
_DB-lang
_Field file:
_Field-Name
_Data-Type
_sys-field
_field-rpos
_Decimals
_Order
_Extent
_Fld-stdtype
_Fld-stlen
_Fld-stoff
_Fld-case
_Index file:
_Index-name
_Unique
_num-comp
_Index-comp file:
_Field-name
_Ascending
_Abbreviate
_Unsorted
The _Sequence file is treated a little differently as follows:
* Creating a new _sequence will not cause a CRC update .
* Updating _seqname will change the crc value of the _sequence record
in the _file file. However, if the update is part of a create
the crc will not be updated.
* An update to any other field in the _sequence record will NOT cause
a CRC update.
* Deletion of a _sequence record will cause a CRC update.
* Any change in the CRC will effectively invalidate any .r's
referencing any sequence via the current-value and next-value
functions.
Note that these comments have more to do with what will cause the CRC
to *change* due to changes in the _Sequence records, rather than which
fields participate in the CRC calculation. This is peculiar to the
_Sequence file, since for all other files any change to a field that
participates in the CRC calculation causes the CRC to be recalculated.
This information was taken from the spec in
language/4GL/sequence_generator.doc.
Progress Software Technical Support Note # 11428