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From: mrspock@hubcap.UUCP (Steve Benz)
Newsgroups: comp.unix.questions,comp.databases
Subject: partial file locking with ndbm(3) files
Keywords: ndbm flock file locking concurrent update
Message-ID: <1768@hubcap.UUCP>
Date: 27 May 88 21:28:55 GMT
Organization: Clemson University, Clemson, SC
Lines: 21


  I'm trying to write a database application (a small one) which
uses ndbm(3).  I'd like to find out how I could write my application
so that a minimum portion of the database is locked at any one
time.  Naturally, the ndbm man page skirts the whole issue of record
locking (What is a concurrent update anyway? :-)

  The most common operations on the database will be (in this order):

   search every record for some trait or another.
   update a single record.
   add a single record.

  I'd rather not lock the whole database when I do a 'search' since
that might hold up the updates&adds for an inordinate amount of time.
While I can readily see how to accomplish a whole-database locking
scheme, I think my performance would be substantially better with
single-record locking.

				- Steve Benz
				...!hubcap!mrspock
				mrspock@hubcap.clemson.edu