added artefact_parent_cache table

htdocs/lib/db/install.xml

@@ -277,6 +277,18 @@
                 <KEY NAME="userfk" TYPE="foreign" FIELDS="owner" REFTABLE="usr" REFFIELDS="id" />
             </KEYS>
         </TABLE>
+        <TABLE NAME="artefact_parent_cache">
+            <FIELDS>
+                <FIELD NAME="artefact" TYPE="int" LENGTH="10" NOTNULL="true" />
+                <FIELD NAME="parent" TYPE="int" LENGTH="10" NOTNULL="true" />
+                <FIELD NAME="depth" TYPE="int" LENGTH="3" />
+            </FIELDS>
+            <KEYS>
+                <KEY NAME="primary" TYPE="primary" FIELDS="artefact,parent" />
+                <KEY NAME="artefactfk" TYPE="foreign" FIELDS="artefact" REFTABLE="artefact" REFFIELDS="id" />
+                <KEY NAME="parentfk" TYPE="foreign" FIELDS="parent" REFTABLE="artefact" REFFIELDS="id" />
+            </KEYS>
+        </TABLE>
         <TABLE NAME="community">
             <FIELDS>
                 <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="true" />