Equivalence of Databases (Notion of)?

In summary, the conversation discusses the possibility of two databases, D1 and D2, being considered the "same" or isomorphic in terms of their functionality. The concept of isomorphism is explained and it is stated that there is no analogous term in relational database theory. The conversation also mentions that the functionality of a database can change due to different requirements and that comparing the semantic/content of different databases is difficult.
  • #1
WWGD
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Hi All,
Say we have two databases D1, D2, with the same number of entities and with equal functionality diagrams
(i.e., the functional dependence graphs are graph-isomorphic). Is there a notion in database under which D1, D2 are considered to be "the same" database , or some term equivalent to the same, as in the term "isomorphic" in Mathematics?
 
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  • #2
Do you mean the "same" schemas, just a different data set? AFAIK there is no really analogous term in relational db theory to isomorphic. And if such a thing existed it would not convey very much meaning. Data in a db changes its functionality due to different requirements for data reporting, for example. We have differing indexes and code hints (for SQL queries in db's with identical schema owners), but because of use patterns (indexes, etc.) are actually different. If this were not true DBA's would be out of work. OR have a lot less to do at any rate.
 
  • #3
Thanks, DH. But isomorphisms most often refer to the preservation of part of the structure, and not all of its aspects, i.e., we can have the Reals be isomorphic to some other set as a group, field, as an ordered field, etc. So I guess the isomorphism here would (it it was defined) preserve the schema, though not necessarily the contents or the semantic aspect. And , is there a way of comparing the semantics/content of different dbs?
 
  • #4
WWGD said:
Thanks, DH.
Um, that was jim mcnamara who replied, not D H.
 

Related to Equivalence of Databases (Notion of)?

1. What is the notion of equivalence of databases?

The notion of equivalence of databases refers to the concept of two databases being functionally identical, meaning they contain the same information and can produce the same results when queried.

2. How is equivalence of databases determined?

Equivalence of databases is determined by comparing the structure, content, and functionality of two databases. This can be done manually or with the use of software tools.

3. What are the benefits of ensuring equivalence of databases?

Ensuring equivalence of databases can prevent data inconsistencies and errors, improve data quality and accuracy, and promote efficient data sharing and integration between systems.

4. Are there different levels of equivalence for databases?

Yes, there are different levels of equivalence for databases, such as logical equivalence, structural equivalence, and functional equivalence. These levels determine the extent to which two databases are considered equivalent.

5. How can equivalence of databases be maintained over time?

To maintain equivalence of databases over time, it is important to establish and follow data management best practices, regularly monitor and update databases, and conduct regular checks for data consistency and accuracy.

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