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Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .... .
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .... .
- From: "Bollinger, John C" <John.Bollinger@STJUDE.ORG>
- Date: Fri, 21 Jan 2011 18:15:56 -0600
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On Friday, January 21, 2011 2:48 PM, Herbert J. Bernstein wrote: >This can be made to work, I am pleased to hear it. > but for my uses, there are >some minor issues: > >1. I will be grouping the primary DDLm tag. With the >_definition.xref_code removed, the primary DDLm tag >will have to be aliased; and Ok. >2. With multiple xref codes for a given tag (e.g. >DDL2 and DDLm), it would be more appropriate to >normalize and put the tags and xref codes into >a sub-category, rather than to keep repeating the >same tag. This would have the advantage of allowing >the alias category to return to a non-compound key >and would also allow all the grouping of >tags in a dictionary to be gathered on a separate >block, if desired. The tags and xref could certainly be moved into a subcategory, but that cannot both reduce duplication and model the same data because (xref_code, definition_id) is a candidate key for whichever category you put it in. Or rather, it could reduce duplication if you pulled ALIAS_XREF up to dictionary level, gave it at least one non-key attribute, and had multiple definitions referring to the same rows, but it doesn't look like that's how Herbert proposes scoping things. >For these reasons, I suggest > >1. Leave _alias.dictionary_uri, but deprecate it in >favor of: I'm missing something here. Why is it appropriate to issue a brand new standard that already contains a deprecated feature? >2. Create an ALIAS_XREF category with the >following tags, forming a composite key > >_alias_group.definition_id > a tag identifier belonging to a group >_alias_group.xref_code > a code identifying a real or virtual dictionary >or other logical groups of tags to which the tag >belongs Thus the repetition of definition_id would appear in ALIAS_XREF instead of in ALIAS, and ALIAS_XREF would have a compound key instead of ALIAS having one. And with this approach there is no way to model a defined item being aliased to some definitions of a particular data name but not to others. We could take this route as long as the last is of no concern. It is unlikely that we would ever encounter a problem in practice. From the perspective of a data modeling purist, however, it makes me uncomfortable. I could live with it, but to me it looks like the benefits don't justify the costs. >The other tags that John proposes for David's uses >actually fit better in terms of normalization in this sub- >category, than on the top level, but that is a decision >for David to make. I am happy either way. The other tags would be _alias.dictionary_version and _alias.deprecated. Herbert is right: if ALIAS_XREF were introduced per his proposal then these attributes would best go there. Personally, I would not be satisfied for ALIAS_XREF to be introduced but these two tags placed in ALIAS instead. I would most prefer, however, to not introduce ALIAS_XREF at all. Regards, John Email Disclaimer: www.stjude.org/emaildisclaimer _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group
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- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .... . (Herbert J. Bernstein)
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- Re: [ddlm-group] Objectives of CIF2 syntax discussion (James Hester)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. . (David Brown)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. . (Bollinger, John C)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. . (Bollinger, John C)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. . (James Hester)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. . (Bollinger, John C)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .. . (Bollinger, John C)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .. . (Herbert J. Bernstein)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .. . (David Brown)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .. . (Bollinger, John C)
- Re: [ddlm-group] Objectives of CIF2 syntax discussion. .. .. .. .. . (Herbert J. Bernstein)
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