http://localhost/ticket/1077 <p> Have developed a new "changeset" based model for revisioning in vdm. This has several advantages: </p> <ul><li>Much simpler </li><li>Cleaner separation of continuity from changesets <ul><li>Supports certain operations that are impossible now (e.g. deleting all changes to a particular object irrespective of whether other objects were changed in same revisions). </li></ul></li><li>Easier support for pending state and similar behaviour </li><li>Almost identical API </li></ul><p> Disadvantages: </p> <ul><li>Difficult to query revision history. Currently we have a way of finding out the diffs of particular packages. These diffs *include* changes to objects associated with packages (i.e a resource attached to a package). With the new model the only way to get this information is by looking in the json stored in the change object which is very awkward. </li></ul><ul><li>Does not give us anything extra if we simplify our use of vdm currently. (see alternative below) </li></ul><ul><li>A large change to database structure needs to happen. </li></ul><h2 id="Implementation">Implementation</h2> <ul><li>The main challenge with this change is schema and data migration </li></ul><h3 id="Migration">Migration</h3> <p> Every revisioned object has a revision_id and revision attribute. </p> <p> Approximate algorithm: </p> <pre class="wiki">Revision -&gt; Changeset for revtype in [PackageRevision, ...]: for pkgrev in package_revision: changeset = lookupchangeset(package_revision) ChangeObject(cset, (table, id), dictize(pkgrev)) </pre><p> Question: </p> <ul><li>does pkg include tags attributes or not? or we have to dictize, pkgrev, pkg2tagrev, and tag. Probably the latter. </li></ul><h2 id="Alternative">Alternative</h2> <p> Instead of restructuring the whole of the database to fit the new changeset model just simplifying our use of the current vdm by removing stateful list/dicts and handling this state ourselves in the logic layer could be adequate. The vdm would then be just a simple copy on write mechanism at the table level. This seems to cover all advantages/disadvantages above. </p> en-us http://assets.okfn.org/p/ckan/img/ckan_logo_shortname.png http://localhost/ticket/1077 Trac 0.12.3 rgrp Mon, 18 Apr 2011 11:36:41 GMT http://localhost/ticket/1077#comment:1 http://localhost/ticket/1077#comment:1 <ul> <li><strong>priority</strong> changed from <em>awaiting triage</em> to <em>critical</em> </li> <li><strong>description</strong> modified (<a href="/ticket/1077?action=diff&amp;version=1">diff</a>) </li> </ul> Ticket kindly Mon, 02 May 2011 11:01:19 GMT http://localhost/ticket/1077#comment:2 http://localhost/ticket/1077#comment:2 <ul> <li><strong>description</strong> modified (<a href="/ticket/1077?action=diff&amp;version=2">diff</a>) </li> </ul> Ticket rgrp Sun, 08 May 2011 12:24:53 GMT http://localhost/ticket/1077#comment:3 http://localhost/ticket/1077#comment:3 <ul> <li><strong>state</strong> set to <em>draft</em> </li> <li><strong>description</strong> modified (<a href="/ticket/1077?action=diff&amp;version=3">diff</a>) </li> </ul> Ticket kindly Sun, 08 May 2011 18:58:07 GMT http://localhost/ticket/1077#comment:4 http://localhost/ticket/1077#comment:4 <ul> <li><strong>description</strong> modified (<a href="/ticket/1077?action=diff&amp;version=4">diff</a>) </li> </ul> Ticket rgrp Thu, 12 May 2011 14:57:51 GMT http://localhost/ticket/1077#comment:5 http://localhost/ticket/1077#comment:5 <ul> <li><strong>description</strong> modified (<a href="/ticket/1077?action=diff&amp;version=5">diff</a>) </li> <li><strong>summary</strong> changed from <em>Switch to new vdm changeset model</em> to <em>Move to simpler vdm system</em> </li> </ul> Ticket shevski Fri, 08 Jul 2011 11:56:54 GMT http://localhost/ticket/1077#comment:6 http://localhost/ticket/1077#comment:6 <ul> <li><strong>milestone</strong> <em>ckan-v1.5</em> deleted </li> </ul> Ticket dread Fri, 28 Oct 2011 10:21:24 GMT http://localhost/ticket/1077#comment:7 http://localhost/ticket/1077#comment:7 <ul> <li><strong>priority</strong> changed from <em>critical</em> to <em>awaiting triage</em> </li> </ul> <p> I guess this is not a priority now. </p> Ticket kindly Mon, 18 Jun 2012 15:45:45 GMT http://localhost/ticket/1077#comment:8 http://localhost/ticket/1077#comment:8 <ul> <li><strong>milestone</strong> set to <em>ckan-backlog</em> </li> </ul> Ticket