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DIABLO-KP(5)		      File Formats Manual		  DIABLO-KP(5)

NAME
       diablo-kp - General KP database support in Diablo

GENERAL
       Diablo  uses a key-token-pair database module to	manage the active file
       (dactive.kp) and	the intent is to use the same database module to  man-
       age the overview	cache and (group,article)->messageid translation data-
       bases for the reader side.  Active  KP  databases  can  be  manipulated
       through	the  dkp  program and inactive KP databases can	be manipulated
       with an editor.	An editor should never be used on an active  KP	 data-
       base.

       The KP database uses an append/replace approach for writing.  Any modi-
       fication	which does not change the length of a  record  is  written  in
       place.	Any  modification which	does change the	length of a record in-
       validates the old record	and appends a new record.  Thus	things such as
       article number updates in dactive.kp may	be done	in place.

       The  KP	database  contains  embedded sort information for each record.
       Sorts are performed on the embedded information field without  actually
       rearranging the database	file.  An append to a KP database does not re-
       quire an	immediate resort.  Lookup failures go through unsorted records
       sequentially.   The  resort  threshold is nominally 64.	 The KP	system
       stores a	modification timestamp on close	and detects a manual  edit  on
       open  by	comparing the modification time	of the KP database against the
       stored timestamp.  This assumes that manual edits only occur while  the
       database	is offline.  Since sort	information is stored as file offsets,
       the KP system will force	a resort if a manual edit was  detected.   You
       can  also  force	 a  resort by setting the cccccccc field in the	header
       (the last 8 digit field on the first line of the	file) to 10000000.

       Due to the resort requirement, the KP system is not designed to	handle
       a  high	append	rate  on large databases.  It is expected to work well
       enough with the active file (which does not require resorts under nomi-
       nal  operation),	 article  translation  databases  which	are relatively
       small and not appended to quickly, and overview caching	databases  for
       the same	reason.	 You can create	a KP database with .B dkp -w database-
       name.kp and read	and write it with similar dkp commands.

CLEANING
       KP databases must be cleaned up occassionally.  To clean	a KP  database
       you  must  first	 take  it offline.  Then a simple egrep	-v '^-'	should
       suffice.	 It is also usually a good idea	to force a resort just in case
       the  system time	is messed up and Diablo	does not detect	the edit.  See
       adm/biweekly.atrim for an example.

       It is possible to clean active KP databases only	if they	are being used
       for  transient read operation.  By doing	an egrep and then renaming the
       new file	over the old one, transient  programs  with  open  descriptors
       will still be able to operate on	the old	version	of the database.

SEE ALSO
       diablo(8), dicmd(8), didump(8), diload(8), dnewslink(8),	doutq(8), dex-
       pire(8),	 dexpireover(8),  diconvhist(8),  dilookup(8),	 dspoolout(8),
       dkp(8), dpath(8), diablo-files(5), diablo-kp(5)

								  DIABLO-KP(5)

NAME | GENERAL | CLEANING | SEE ALSO

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