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POAre modifiable join views a reasonable design choice?
 

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  1. POAre modifiable join views a reasonable design choice?
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    <p>To be clear, by <em>modifiable <strong>join</strong> view</em> I mean a view constructed from the joining of two or more tables that allows insert/update/delete actions that modify any/all of the component tables.</p> <p>This may be a postgres specific question, not sure. I am also interested if other DBMSs have idiosyncratic features for modifiable join views, since as far as I can tell, they are not possible in standard SQL.</p> <p>I'm working on a postgres schema, and some of my recent reading has suggested that it is possible to construct modifiable join views using instead rules (<code>CREATE RULE ... DO INSTEAD ...</code>). Modifiable join views seem desirable since it would allow for hiding strong normalization behind an interface, providing a mechanism for classic abstraction. Rules are the only option for implementation, since currently <a href="http://www.postgresql.org/docs/9.0/static/rules-triggers.html" rel="nofollow noreferrer">triggers cannot be set on views</a>.</p> <p>However, the first modifiable view I tried to design ran into problems, and I find out that many consider non-trivial rules to be harmful (see links in comments to <a href="https://stackoverflow.com/questions/5534927/how-to-write-a-delete-rule-on-a-view/5536199#5536199">this SO answer</a>). Also, I can't find any examples of modifiable join views on the web.</p> <p><strong>Questions (Edit to put finer points on the questions):</strong></p> <ul> <li>Do you have any experience with modifiable join views and can you provide a concrete example with select/insert/delete/update ability? </li> <li>Are they practical, i.e. can they be treated transparently without having to tiptoe around mines/black holes? </li> <li>Are they ever a good design choice, in terms of functionality/effort ratio and maintainability? </li> </ul> <p>Would greatly appreciate links to any examples/discussions on this topic. Thanks.</p>
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    1. COBlog from one of the developers on views: http://petereisentraut.blogspot.com/2010/07/update-on-views.html
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