[MarkLogic Dev General] About hash map function

[Ian Small]

Alternatively, xdmp:query-meters() will return the actual wallclock time
as part of its output.  Two potential issues with this:
- resolution of timer of your operating system may still be "too fast"
- arguably, using a sledgehammer for a fly, considering the size of the
structure that query-meters() returns, when all you want is the
wallclock time

I prefer pure random()-based or hybrid (ie. stable clock + random etc.)
approaches myself. 

ian

-----Original Message-----
From: general-bounces at developer.marklogic.com
[mailto:general-bounces at developer.marklogic.com] On Behalf Of Gerety,
Colin
Sent: Monday, May 14, 2007 2:17 PM
To: General Mark Logic Developer Discussion
Subject: RE: [MarkLogic Dev General] About hash map function

Thanks for pointing out that current-dateTime() is "stable".  I had
missed that.

Colin Gerety
Flatirons Solutions Corporation

-----Original Message-----
From: general-bounces at developer.marklogic.com
[mailto:general-bounces at developer.marklogic.com] On Behalf Of Ryan Grimm
Sent: Monday, May 14, 2007 3:05 PM
To: General Mark Logic Developer Discussion
Subject: Re: [MarkLogic Dev General] About hash map function

Hi Rashid,

In XQuery, the current-dateTime() will always return the same value
during the execution of the query.  To see this try executing this
query:

current-dateTime(),
xdmp:sleep(5000),
current-dateTime()

You'll see that result of current-dateTime() is the same for both calls
even though there was a sleep in there for 5 seconds.

If you're looking for a unique value for some id's you could probably
use xdmp:random() to generate an unsigned 64bit integer.  While there is

a small possibility of xdmp:random() returning the same value twice, the

  same potential problem exists for xdmp:hash64().

Hope that helps.

--Ryan


Nizamuddin, Rashid wrote:
> Could anybody please tell me why I am not getting a unique value when
I 
> execute this loop
> 
> *let $cnt := 1 to 5*
> 
> *for $c in $cnt*
> 
> *return *
> 
> *    let $str := xdmp:hash64(string(current-dateTime()))*
> 
> *    return $str*
> 
> * *
> 
> *for each iteration I get the same value. I need to get a unique value

> to insert in some ids elements.*
> 
> * *
> 
> *Any help will be appreciated*
> 
> * *
> 
> *Rashid*
> 
> * *
> 
> 
>
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