Re: Persistence


frebe73@xxxxxxxxx wrote:
In the OO world, people often claim that they use a SQL database "for
persistence". Mostly I think that the person making that claim actually
uses other features - like transactions, integrity, queries, etc - and
just use the word persistence because it's a buzzword. But sometimes
there are people that claims that only the persistence features of a
SQL database should be used or that a SQL database does not provide any
other features but persistence.

What are the opinitions at comp.object?

While relational models focus on flexibility in how they represent
information, object models don't benefit from this flexibility. There
is no single object model that can express enough semantic precision
for all applications. Object models aren't supposed to capture all the
relationships among the information components, only those that are
relevant to the business context of a particular application. Of
course, several alternative object models can be assembled from
components in the same relational model. So think of the relational
database as a store of information components, as an engine for
querying those components, for maintaining integrity constraints across
those components, for supporting transactional updates of those
components, and think of an object model as one of a number of possible
assemblies of those components.

There are likely a few cases where it makes sense to persist objects
directly, but I think those are relatively rare.

Regards,
Daniel Parker

.

Relevant Pages

  • Re: Persistence
    ... If you have such features ... Persistence is strictly about object IO. ... The relational model has nothing to do with disk storage. ...
    (comp.object)
  • Re: SQL
    ... persistence is one of MANY features of a DB. ... > or less) to the relational model, and and it does so in a persistent ... >>> databases. ...
    (comp.object)
  • Re: Persistence
    ... If you have such features ... Persistence is strictly about object IO. ... There is no direct support of object storage and subsequent ... instantiation of objects from disk storage. ...
    (comp.object)
  • Re: Relational database & OO
    ... data to a persistence storage medium. ... using the features already provided by the RDBMS, ... Caching is the second issue. ...
    (comp.object)
  • Re: SQL
    ... My point is that these features are useful non-persistence features ... "If we ignore the persistence aspect, ... I don't claim that a RDBMS is the only product that may ... > Do you have any examples of relational databases that have specific features ...
    (comp.object)