Re: data queues

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Hello Vernon,

Indexed data queues are simply sorted on the key value.  On CISC systems the 
queue is sorted when entries are 
added; RISC system do the sort when entries are retrieved.  The sort is a not 
at all efficient On2 (how do I do 
a superscript in this mail program???? -- that is meant to mean 
Order-n-squared).  That is why IBM recommend 
keeping the number of entries in a data queue to a minimum.  The more there are 
the longer the sort will take 
-- can be hours for hundreds of entries (guess how I found out!!).

User queues are more efficient but I'm not sure of the key implementation.  
User indices expose the system 
independent index support and do use the internal binary radix tree

Regards,
Simon Coulter.

//----------------------------------------------------------
// FlyByNight Software         AS/400 Technical Specialists
// Phone: +61 3 9419 0175      Mobile: +61 0411 091 400
// Fax:   +61 3 9419 0175      E-mail: shc@flybynight.com.au
// 
// Windoze should not be open at Warp speed.
 

//--- forwarded letter -------------------------------------------------------
> X-Mailer: QUALCOMM Windows Eudora Pro Version 3.0.5 (32)
> Date: Sat, 23 May 98 21:25:08 -0500
> From: "Vernon Hamberg" <hambergv@goldengate.net>
> To: MIDRANGE-L@midrange.com
> Reply-To: MIDRANGE-L@midrange.com
> Cc: juris@rfb.lv
> Subject: Re: data queues

> 
> At 04:24 PM 1/22/98 +0200, you wrote:
> >I would be grateful if somebody would give a brief summary on data
> >queues, their usage, application and etc.
> >
> >Thanks.
> >
> >Juris.
> 
> In addition to all the other good information you've evoked, let me add a
> couple thoughts.
> 
> 1. Data queues implement what are commonly known as stacks and queues in
> C-language development contexts. All the hard work of writing those things
> has been done for us by IBM (Yay!). A nice implementation of the
> object-oriented concept of "Just give me the interface to an object—I don't
> need to know the way it works".
> 
> 2. Data queues can be keyed (binary tree?), as well as LIFO (stack) or FIFO
> (queue).
> 
> Cheers
> 
> Vernon Hamberg
> Systems Software Programmer
> Old Republic National Title Insurance Company
> 400 Second Avenue South
> Minneapolis, MN  55401-2499
> (612) 371-1111 x480

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