Re: Navigation question
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 21 Feb 2007 15:27:24 GMT
Message-ID: <wxZCh.9057$R71.140171_at_ursa-nb00s0.nbnet.nb.ca>
>
> 19:47, "Marshall" <marshall.spi..._at_gmail.com> wrote:
>
>
> to
>
>
> You are right. See my comments elsewhere in this discussion concening data
> dependency.
>
> Arguing for the RM on performance reasons alone is a mistaken argument. In
> general equivalent Codasyl databases will outperform relational databases.
Date: Wed, 21 Feb 2007 15:27:24 GMT
Message-ID: <wxZCh.9057$R71.140171_at_ursa-nb00s0.nbnet.nb.ca>
Walt wrote:
> "Andy Dingley" <dingbat_at_codesmiths.com> wrote in message
> news:1172053637.665300.7510_at_a75g2000cwd.googlegroups.com...
>
>>On 20 Feb, 17:57, "Walt" <wami..._at_verizon.net> wrote: >> >>>"Andy Dingley" <ding..._at_codesmiths.com> wrote in message >>> >>>news:1171990396.924858.28580_at_p10g2000cwp.googlegroups.com...> On 14 Feb,
>
> 19:47, "Marshall" <marshall.spi..._at_gmail.com> wrote:
>
>>>>>select * from orders where date > '2006-01-01' and status = >>>>>'fulfilled' and customerid = 1234 >>> >>>>>You say what you want and you get just that. No sifting >>>>>through stuff you don't want; no navigating. >>> >>>>Why is that good though? Because it avoids navigation, or because it >>>>avoids round-tripping? >>>>IMHO it's avoiding the second thhat is the advantage here, not the >>>>first >>> >>>Neither of the above. It's good because it does not require the inquirer
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> to
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>>>know about anything other than the data. >> >>That depends on what you care about most. IMHO, it's _both_ that are >>important, however some may be locally more important than others. >> >>My experience comes from mid-size intranet web apps, where the real >>performance hit comes from excess round-tripping to the DB server. I >>would agree completely with Marshall's comment, "If get-customer and >>get-order run over the network, then >>this software will perform poorly." However I don't see >>_this_statement_alone_ as sufficient reason to avoid navigational >>solutions. You can navigate on the DB server alone without requiring >>round-tripping.
>
> You are right. See my comments elsewhere in this discussion concening data
> dependency.
>
> Arguing for the RM on performance reasons alone is a mistaken argument. In
> general equivalent Codasyl databases will outperform relational databases.
I disagree.
> It's when you go to use the data in unforeseen ways that the RM pulls ahead.
Certainly, this is true, and it is an important physical performance consideration.
> Many of the best arguments for RM apply only to "nexus databases" rather
> than to "embedded databases".
Almost my entire career involved embedded databases. The arguments for RM apply equally for them.
[snip]
I direct you to Date's _Principle of Incoherence_. Received on Wed Feb 21 2007 - 16:27:24 CET