Re: Thanks: TurboIMAGE B-Tree indices

Paul wrote:

Walter, after a DBFIND, check the value in the status array of the
CHAIN-COUNT element(4th) for zero. If so, there are no records in that

chain in the detail. I always do this to avoid an unnecessary DBGET
and
the associated disk I/O.

A couple of thoughts here.

1. In the situation I was describing, I had done a high-speed (mode 24)
B-Tree DBFIND, followed by a traversal of the super-chain. I don't
think the technique Paul describes would apply in that case.

2. In the case of a non-B-Tree DBFIND, yes, checking the chain count
can help avoid an unnecessary call to DBGET. But I wonder whether that
would actually avoid any disc I/O. Since the internally maintained
forward (and backward) pointer would be zero, I would expect IMAGE to
return immediately with an end-of-chain status, with no need for any
disc I/O.

Walter

Walter J. Murray

* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *

.

Relevant Pages

  • Re: Referential Integrity
    ... Walter, what I don't understand is why you want the zero. ... Drag the MemberID field into the grid. ... >>>>If the foreign key is a Number type field, ...
    (microsoft.public.access.forms)
  • Re: 1c+1c Closing Velocity...,answer to Henri Wilson
    ... >> You might find a few in cool stars. ... Paul, the average molecular speed is zero in any direction. ... >So the distribution of the radial velocity component ...
    (sci.physics.relativity)
  • Re: Printer woes resolved
    ... At the time it appeared that if I included the leading zero it tried to ... Native Mode Spooler message 9038 ... To join/leave the list, search archives, change list settings, * ...
    (comp.sys.hp.mpe)
  • Re: OT: Analysts Warn of Spending Impact
    ... being told you couldn't divide by zero... ... woman and child in the US... ... * To join/leave the list, search archives, change list settings, * ...
    (comp.sys.hp.mpe)
  • Re: Is physics a science?
    ... "It is, to me, interesting to note that that these MUST be of opposite ... are not zero. ... kinetic system of particles they cannot be zero... ... we are discussing the web page entitled "Paul Stowe's ...
    (sci.physics.relativity)
Loading