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Posted to ojb-dev@db.apache.org by th...@apache.org on 2003/01/31 07:56:49 UTC
cvs commit: jakarta-ojb/xdocs faq.xml
thma 2003/01/30 22:56:49
Modified: xdocs faq.xml
Log:
- restructuring faq
- adding new q & a
Revision Changes Path
1.12 +60 -6 jakarta-ojb/xdocs/faq.xml
Index: faq.xml
===================================================================
RCS file: /home/cvs/jakarta-ojb/xdocs/faq.xml,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -r1.11 -r1.12
--- faq.xml 21 Dec 2002 16:17:34 -0000 1.11
+++ faq.xml 31 Jan 2003 06:56:49 -0000 1.12
@@ -10,23 +10,43 @@
<body>
<section name="Frequently Asked Questions" anchor="faq">
+ <p><b>General</b></p>
+ <ul>
+ <li><a href="#3">Why OJB? Why do we need another O/R mapping tool?</a></li>
+ <li><a href="#8">How is OJB related to ODMG and JDO?</a></li>
+ <li><a href="#17">What are the OJB design principals?</a></li>
+ <li><a href="#18">Where can I learn more about Object/Relational mapping in general?</a></li>
+
+ </ul>
+
+ <p><b>Getting started</b></p>
<ul>
<li><a href="#1">Help! I'm having problems installing and using OJB!</a></li>
<li><a href="#2">Help! I still have serious problems installing OJB!</a></li>
- <li><a href="#3">Why OJB? Why do we need another O/R mapping tool?</a></li>
<li><a href="#4">Does OJB support my RDBMS?</a></li>
+ <li><a href="#10">What are the OJB internal tables for?</a></li>
+
+ </ul>
+
+ <p><b>OJB APIs</b></p>
+ <ul>
+ <li><a href="#9">What are the differences between the PersistenceBroker API and the ODMG API? Which one should I use in my applications?</a></li>
+ <li><a href="#15">I don't like OQL, can I use the PersistenceBroker Queries within ODMG?</a></li>
+ <li><a href="#16">The OJB JDO implementation is not finished, how can I start using OJB?</a></li>
+
+ </ul>
+
+ <p><b>Howto</b></p>
+ <ul>
<li><a href="#5">How to use OJB with my RDBMS?</a></li>
<li><a href="#6">How to page and sort?</a></li>
<li><a href="#7">What about performance and memory usage if thousands of objects matching a query are returned as a Collection?</a></li>
- <li><a href="#8">How is OJB related to ODMG and JDO?</a></li>
- <li><a href="#9">What are the differences between the PersistenceBroker API and the ODMG API? Which one should I use in my applications?</a></li>
- <li><a href="#10">What are the OJB internal tables for?</a></li>
<li><a href="#11">When is it helpful to use Proxy Classes?</a></li>
<li><a href="#12">How can I convert data between RDBMS and OJB?</a></li>
<li><a href="#13">How can I trace and/or profile SQL statements executed by OJB?</a></li>
<li><a href="#14">How does OJB manage foreign keys?</a></li>
- <li><a href="#15">I don't like OQL, can I use the PersistenceBroker Queries within ODMG?</a></li>
- <li><a href="#16">The OJB JDO implementation is not finished, how can I start using OJB?</a></li>
+ <li><a href="#19">How can Collections of primitive typed elements be mapped?</a></li>
+
</ul>
<subsection name="Help! I'm having problems installing and using OJB!" anchor="1">
@@ -199,6 +219,40 @@
</ul>
</p>
</subsection>
+
+ <subsection name="What are the OJB design principals?" anchor="17">
+ <p>
+ OJB has a "pattern driven" design.
+ <a href="links.html#design">Please refer to this document for more details</a>
+ </p>
+ </subsection>
+
+ <subsection name="Where can I learn more about Object/Relational mapping in general?" anchor="18">
+ <p>
+ <a href="links.html#further readings on O/R mapping">We have a link list pointing to further readings.</a>
+ </p>
+ </subsection>
+
+ <subsection name="How can Collections of primitive typed elements be mapped?" anchor="19">
+ <p>
+ The first thing to ask is:
+ How are these primitive typed elements (Strings are also treated as primitive types here)
+ stored in the database.<br/>
+ 1) are they treated as ordinary domain objects and stored in a separate table?<br/>
+ 2) are they serialized into a Varchar field?<br/>
+ 3) are they stored as a comma separated varchar field?<br/>
+ 4) is each element of the vector or array stored in a separate column?
+ (this solution does only work for a fixed number of elements!)<br/>
+ <br/>
+ Follow these steps for solution 3):<br/>
+ a) simply define ordinary collection-descriptors as for every other collection of domain objects.<br/>
+ b) use the Object2ByteArrFieldConversion. See jdbc-types.html for details on conversion strategies.<br/>
+ c) use the StringVector2VarcharFieldConversion. See jdbc-types.html for details on conversion strategies.<br/>
+ d) provide a field-descriptor for each element.
+
+ </p>
+ </subsection>
+
<subsection name="Does OJB support my RDBMS?" anchor="4">
<p>