[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Reply to: [list | sender only]
Re: [ddlm-group] LOOP versus LIST
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] LOOP versus LIST
- From: Nick Spadaccini <nick@csse.uwa.edu.au>
- Date: Mon, 08 Feb 2010 11:43:06 +0800
- Authentication-Results: postfix;
- In-Reply-To: <alpine.BSF.2.00.1002051139020.96070@epsilon.pair.com>
On 6/02/10 12:48 AM, "Herbert J. Bernstein" <yaya@bernstein-plus-sons.com> wrote: > The real issue here is the data model that we are supporting -- databases > or something with tighter control over internals. Especially after the > discussions at the ESRF HDF5 hyperspectral data workshop last month, I am > increasingly convinced that it is a serious mistake to move away from > the database model. While tighter control over internals is tempting, in > the end, as we move more into multithreaded, multiprocessor multiwriter > applications, the greater the performance penalty we will pay for > over-specifying the internal representation of a CIF, especially in ways > that deviate from the relational model. I agree that in essence we are enshrining a database model in what we do. Though I am not keen that the only model we consider is the relational model. Though the current form of CIF maps easily in to the relation model it is not required to. But I agree having database model(s) in mind with what we do is essential. > Nothing is gained for users in making a mandatory distinction between > single row loops and the same tags with individual values. I propose > that CIF2 adopt the DDL2 mmCIF approach of treating them as equivalent. > Joe is right that having the distinction in the DDL then forces all > parsers to refer to the dictionary to be able to make this pointless > distinction. But in most databases you define the schema (attribute ordering and type etc) and then load multiple records. Yes you can update and insert one at a time where you have a flattening of the loop, but that is more with updating and changing. I can see a lot of application level software that would handle individual rows in this way, but CIF is meant to be an archiving formalism and to that extent I think it is more helpful to (at least in archiving) maintain a clear consistency between the schema (DDL) and the data file. cheers Nick -------------------------------- Associate Professor N. Spadaccini, PhD School of Computer Science & Software Engineering The University of Western Australia t: +61 (0)8 6488 3452 35 Stirling Highway f: +61 (0)8 6488 1089 CRAWLEY, Perth, WA 6009 AUSTRALIA w3: www.csse.uwa.edu.au/~nick MBDP M002 CRICOS Provider Code: 00126G e: Nick.Spadaccini@uwa.edu.au _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group
Reply to: [list | sender only]
- References:
- Re: [ddlm-group] LOOP versus LIST (Herbert J. Bernstein)
- Prev by Date: Re: [ddlm-group] LOOP versus LIST
- Next by Date: Re: [ddlm-group] Case sensitivity
- Prev by thread: Re: [ddlm-group] LOOP versus LIST
- Next by thread: Re: [ddlm-group] LOOP versus LIST
- Index(es):