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#31
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#32
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#33
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Example: Let E1 and E2 be two entities of the same type. Suppose they change the value of their properties. It is quite clear that this can happen at the same time and that E1 and E2 can have all of the exact same attributes. That which is very bad for Anchor Modeling here is that the identities of these two entities are different, even though these two entities are exactly the same in the database, and in the real world. In this example, a variety of combinations and variations can occur, especially since the authors of Anchor Modeling allow the deletion of erroneous data. Vladimir Odrljin |
#34
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(ii) Let E1 be the entity in the "Anchor Model" whose anchor key = 234 and which has three attributes that in time t1 have the values v1, v2, v3 respectively. One can insert another entity whose anchor key = 567 and whose three attributes at the same time t1 have again the values v1, v2, v3 respectively. So we get two entities which have the same attribute values in the database. This implies that we have two entities in the real world, which have the same attributes in the time t1. These two entities have different surrogate keys. We know that this is nonsense in the ER model and Relational model. But we also see that "Anchor Model" supports this nonsense. So anybody can enter the same entities with different suroggates. In this example, a variety of combinations and variations can occur, especially since the authors of Anchor Modeling allow the deletion of erroneous data. |
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(iii) Today the vast majority of keys use the industry standard, probably more than 90% of databases use this type of keys. For example, VIN, Bank account, SSN, etc. In this case too "Anchor Modeling" does not make sense. |
#35
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#36
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In this post I will concentrate on the following two: (a) A New Definition of ''historized attribute'': Definition 7 (Historized Attribute). A historized attribute BH is a string. A historized attribute BH has an anchor A for domain, a data type D for range, and a time type T as time range. An extension of a historized attribute BH is a relation over I x D x T. |
#37
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In this new version from December 2010, the authors of the ''Anchor Modeling'' introduce the identifier of a relationship (see Definition 16). This definition is a sub case of the identifier of the state of a relationship from my data model (see 4.2.4.1, 4.2.4.2, 4.2.5, 4.2.6, 4.2.7, 4.2.8 and 4.2.9 in my paper from 2008). Note that I presented the main ideas about the identifier of a state of an entity or relationship in my paper from 2005, five years prior to 2010. |
#38
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On 6 srp, 22:58, vldm10 <vld... (AT) yahoo (DOT) com |
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