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Daanse Tutorial - Writeback Parent-Child ​

Daanse Tutorial — Writeback with a parent-child hierarchy.

The minimal example showing how writeback works against a ParentChildHierarchy. One self-referencing dimension table NODE (KEY, NAME, PARENT_KEY) defines an arbitrary-depth tree, the fact table FACT posts values against any node, and a FACTWB writeback table receives user-entered adjustments.

When the user writes a value at an intermediate node (e.g. a parent in the tree), the runtime allocates the value across the descendant leaves per the chosen AllocationPolicy — exactly the same behaviour as for a multi-level explicit hierarchy. The interesting part is that for a parent-child hierarchy the set of leaves is computed by walking the self-referencing relationship at cube-init time, not from a fixed level depth.

Database Schema ​

Three tables:

  • FACT — NODE, VALUE. One row per fact posting, with NODE referencing the leaf node and VALUE the numeric amount.
  • NODE — KEY, NAME, PARENT_KEY. The self-referencing dimension table. Root rows have an empty PARENT_KEY (matching the configured nullParentValue = ""). Members at any depth share the same level definition.
  • FACTWB — NODE, VALUE, ID, USER. The writeback target. ID is filled by the engine with a UUID, USER with the session user.
xml
<relational:Schema xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"  xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmi:id="_schema">
  <ownedElement xsi:type="relational:Table" xmi:id="_table_fact" name="FACT">
    <feature xsi:type="relational:Column" xmi:id="_column_fact_node" name="NODE"/>
    <feature xsi:type="relational:Column" xmi:id="_column_fact_value" name="VALUE"/>
  </ownedElement>
  <ownedElement xsi:type="relational:Table" xmi:id="_table_node" name="NODE">
    <feature xsi:type="relational:Column" xmi:id="_column_node_key" name="KEY"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_name" name="NAME"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_parent_key" name="PARENT_KEY"/>
  </ownedElement>
  <ownedElement xsi:type="relational:Table" xmi:id="_table_factwb" name="FACTWB">
    <feature xsi:type="relational:Column" xmi:id="_column_factwb_node" name="NODE"/>
    <feature xsi:type="relational:Column" xmi:id="_column_factwb_value" name="VALUE"/>
    <feature xsi:type="relational:Column" xmi:id="_column_factwb_id" name="ID"/>
    <feature xsi:type="relational:Column" xmi:id="_column_factwb_user" name="USER"/>
  </ownedElement>
</relational:Schema>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Fact Query ​

Plain TableSource over FACT.

xml
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"  xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolapsrc="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/source">
  <rolapsrc:TableSource xmi:id="_tablesource_fact" table="_table_fact"/>
  <relational:Table xmi:id="_table_fact" name="FACT">
    <feature xsi:type="relational:Column" xmi:id="_column_fact_node" name="NODE"/>
    <feature xsi:type="relational:Column" xmi:id="_column_fact_value" name="VALUE"/>
  </relational:Table>
</xmi:XMI>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Tree dimension ​

One dimension Tree with a single-level ParentChildHierarchy. The level keys on the KEY column; the PARENT_KEY column wires the self-reference, and nullParentValue = "" marks the roots. The fact joins on FACT.NODE = NODE.KEY — at every level of the tree, the same column carries the join key.

xml
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"  xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolapdim="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension" xmlns:rolaphier="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy" xmlns:rolaplev="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy/level" xmlns:rolapsrc="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/source">
  <rolapdim:StandardDimension xmi:id="_standarddimension_tree" name="Tree" hierarchies="_parentchildhierarchy_tree"/>
  <rolaphier:ParentChildHierarchy xmi:id="_parentchildhierarchy_tree" name="Tree" allMemberName="All Nodes" primaryKey="_column_node_key" source="_tablesource_node" nullParentValue="" parentColumn="_column_node_parent_key" level="_level_node"/>
  <rolaplev:Level xmi:id="_level_node" name="Node" column="_column_node_key" nameColumn="_column_node_name" uniqueMembers="true"/>
  <rolapsrc:TableSource xmi:id="_tablesource_node" table="_table_node"/>
  <relational:Table xmi:id="_table_node" name="NODE">
    <feature xsi:type="relational:Column" xmi:id="_column_node_key" name="KEY"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_name" name="NAME"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_parent_key" name="PARENT_KEY"/>
  </relational:Table>
</xmi:XMI>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

ParentChildHierarchy ​

ParentChildHierarchy
  ├── name = "Tree"
  ├── hasAll = true
  ├── allMemberName = "All Nodes"
  ├── primaryKey  = NODE.KEY
  ├── parentColumn = NODE.PARENT_KEY
  ├── nullParentValue = ""
  ├── source = NodeTableSource
  └── level("Node") with column = NODE.KEY, nameColumn = NODE.NAME

setUniqueMembers(true) on the level is appropriate here because every parent-child member is uniquely identified by its KEY value, regardless of depth.

xml
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"  xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolaphier="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy" xmlns:rolaplev="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy/level" xmlns:rolapsrc="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/source">
  <rolaphier:ParentChildHierarchy xmi:id="_parentchildhierarchy_tree" name="Tree" allMemberName="All Nodes" primaryKey="_column_node_key" source="_tablesource_node" nullParentValue="" parentColumn="_column_node_parent_key" level="_level_node"/>
  <rolaplev:Level xmi:id="_level_node" name="Node" column="_column_node_key" nameColumn="_column_node_name" uniqueMembers="true"/>
  <rolapsrc:TableSource xmi:id="_tablesource_node" table="_table_node"/>
  <relational:Table xmi:id="_table_node" name="NODE">
    <feature xsi:type="relational:Column" xmi:id="_column_node_key" name="KEY"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_name" name="NAME"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_parent_key" name="PARENT_KEY"/>
  </relational:Table>
</xmi:XMI>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Writeback (FACTWB) ​

The cube wires the Value measure into a single-measure writeback table:

WritebackTable("FACTWB")                     [database.writeback]
  ├── WritebackAttribute(Tree connector) → NODE   [database.writeback]
  └── WritebackMeasure("Value")          → VALUE  [olap.cube.measure]

Behaviour at write time. A Cell.setValue([Measures].[Value], 100, EQUAL_ALLOCATION, ...) at any node — root, intermediate or leaf — drives the engine to:

  1. Walk the self-referencing NODE.PARENT_KEY chain to compute the leaves of the addressed node.
  2. Spread the 100 value across those leaves per the chosen AllocationPolicy — EQUAL_ALLOCATION gives every leaf 100 / N, EQUAL_INCREMENT adds (100 - oldValue) / N to each.
  3. Emit one row per leaf into FACTWB with the leaf's KEY as NODE, the allocated portion as VALUE, a fresh UUID as ID, and the session user as USER.

Behaviour at read time. A subsequent MDX query for any node sums fact rows plus writeback rows under that subtree via the standard SQL aggregation path — no special handling needed, because the writeback table has the same shape as the fact and both are aggregated by the cube's SumMeasure.

Where the measure lives. WritebackMeasure is now in the olap.cube.measure ecore package (alongside SumMeasure, TextAggMeasure, …) — it is conceptually a measure that happens to be paired with a database column for persistence. Only the writeback infrastructure (WritebackTable, WritebackAttribute) remains in database.writeback. In Java the factory call is MeasureFactory.eINSTANCE.createWritebackMeasure().

xml
<rolapwb:WritebackTable xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:rolapwb="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/writeback" xmi:id="_writebacktable_factwb" name="FACTWB">
  <writebackAttribute xmi:id="_writebackattribute_node">
    <column href="_column_factwb_node"/>
    <dimensionConnector href="_dimensionconnector_tree"/>
  </writebackAttribute>
  <writebackMeasure xmi:id="_writebackmeasure_value" name="Value">
    <column href="_column_factwb_value"/>
  </writebackMeasure>
</rolapwb:WritebackTable>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Cube C ​

One physical cube C over FACT with one DimensionConnector (Tree → FACT.NODE), one MeasureGroup holding the Value sum measure, and the FACTWB writeback table.

xml
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"  xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolapcube="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/cube" xmlns:rolapdim="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension" xmlns:rolaphier="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy" xmlns:rolaplev="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy/level" xmlns:rolapmeas="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/cube/measure" xmlns:rolapsrc="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/source">
  <rolapcube:PhysicalCube xmi:id="_physicalcube_c" name="C" source="_tablesource_fact">
    <dimensionConnectors xmi:id="_dimensionconnector_tree" foreignKey="_column_fact_node" dimension="_standarddimension_tree" overrideDimensionName="Tree"/>
    <writebackTable xmi:id="_writebacktable_factwb" name="FACTWB">
      <writebackAttribute xmi:id="_writebackattribute_node" dimensionConnector="_dimensionconnector_tree">
        <column href="_column_factwb_node"/>
      </writebackAttribute>
      <writebackMeasure xmi:id="_writebackmeasure_value" name="Value">
        <column href="_column_factwb_value"/>
      </writebackMeasure>
    </writebackTable>
    <measureGroups xmi:id="_measuregroup">
      <measures xsi:type="rolapmeas:SumMeasure" xmi:id="_summeasure_value" name="Value" formatString=",##0" column="_column_fact_value"/>
    </measureGroups>
  </rolapcube:PhysicalCube>
  <relational:Table xmi:id="_table_fact" name="FACT">
    <feature xsi:type="relational:Column" xmi:id="_column_fact_node" name="NODE"/>
    <feature xsi:type="relational:Column" xmi:id="_column_fact_value" name="VALUE"/>
  </relational:Table>
  <relational:Table xmi:id="_table_node" name="NODE">
    <feature xsi:type="relational:Column" xmi:id="_column_node_key" name="KEY"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_name" name="NAME"/>
    <feature xsi:type="relational:Column" xmi:id="_column_node_parent_key" name="PARENT_KEY"/>
  </relational:Table>
  <rolapdim:StandardDimension xmi:id="_standarddimension_tree" name="Tree" hierarchies="_parentchildhierarchy_tree"/>
  <rolaphier:ParentChildHierarchy xmi:id="_parentchildhierarchy_tree" name="Tree" allMemberName="All Nodes" primaryKey="_column_node_key" source="_tablesource_node" nullParentValue="" parentColumn="_column_node_parent_key" level="_level_node"/>
  <rolaplev:Level xmi:id="_level_node" name="Node" column="_column_node_key" nameColumn="_column_node_name" uniqueMembers="true"/>
  <rolapsrc:TableSource xmi:id="_tablesource_node" table="_table_node"/>
  <rolapsrc:TableSource xmi:id="_tablesource_fact" table="_table_fact"/>
</xmi:XMI>

Note: This is only a symbolic example. For the exact definition, see the Definition section.

Definition ​

This file represents the complete definition of the catalog.

xml
<?xml version="1.0" encoding="UTF-8"?>
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:relational="http://www.omg.org/spec/CWM/1.1/resource/relational" xmlns:rolapcat="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/catalog" xmlns:rolapcube="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/cube" xmlns:rolapdim="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension" xmlns:rolaphier="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy" xmlns:rolaplev="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/dimension/hierarchy/level" xmlns:rolapmeas="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/olap/cube/measure" xmlns:rolapsrc="https://www.daanse.org/spec/org.eclipse.daanse.rolap.mapping/database/source">
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_character_varying" name="CHARACTER VARYING" structuralFeature="_column_factwb_id _column_node_key _column_node_name _column_fact_node _column_factwb_node _column_node_parent_key _column_factwb_user" typeNumber="12"/>
  <relational:SQLSimpleType xmi:id="_sqlsimpletype_integer" name="INTEGER" structuralFeature="_column_fact_value _column_factwb_value" typeNumber="4"/>
  <rolapcat:Catalog xmi:id="_catalog_writeback_parent_child" description="Minimal writeback example against a ParentChildHierarchy." name="Daanse Tutorial - Writeback Parent-Child" cubes="_physicalcube_c" dbschemas="_schema"/>
  <relational:Schema xmi:id="_schema">
    <ownedElement xsi:type="relational:Table" xmi:id="_table_fact" name="FACT">
      <feature xsi:type="relational:Column" xmi:id="_column_fact_node" name="NODE" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_fact_value" name="VALUE" type="_sqlsimpletype_integer"/>
    </ownedElement>
    <ownedElement xsi:type="relational:Table" xmi:id="_table_node" name="NODE">
      <feature xsi:type="relational:Column" xmi:id="_column_node_key" name="KEY" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_node_name" name="NAME" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_node_parent_key" name="PARENT_KEY" type="_sqlsimpletype_character_varying"/>
    </ownedElement>
    <ownedElement xsi:type="relational:Table" xmi:id="_table_factwb" name="FACTWB">
      <feature xsi:type="relational:Column" xmi:id="_column_factwb_node" name="NODE" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_factwb_value" name="VALUE" type="_sqlsimpletype_integer"/>
      <feature xsi:type="relational:Column" xmi:id="_column_factwb_id" name="ID" type="_sqlsimpletype_character_varying"/>
      <feature xsi:type="relational:Column" xmi:id="_column_factwb_user" name="USER" type="_sqlsimpletype_character_varying"/>
    </ownedElement>
  </relational:Schema>
  <rolapsrc:TableSource xmi:id="_tablesource_node" table="_table_node"/>
  <rolapsrc:TableSource xmi:id="_tablesource_fact" table="_table_fact"/>
  <rolaplev:Level xmi:id="_level_node" name="Node" column="_column_node_key" nameColumn="_column_node_name" uniqueMembers="true"/>
  <rolaphier:ParentChildHierarchy xmi:id="_parentchildhierarchy_tree" name="Tree" allMemberName="All Nodes" primaryKey="_column_node_key" source="_tablesource_node" nullParentValue="" parentColumn="_column_node_parent_key" level="_level_node"/>
  <rolapdim:StandardDimension xmi:id="_standarddimension_tree" name="Tree" hierarchies="_parentchildhierarchy_tree"/>
  <rolapcube:PhysicalCube xmi:id="_physicalcube_c" name="C" source="_tablesource_fact">
    <dimensionConnectors xmi:id="_dimensionconnector_tree" foreignKey="_column_fact_node" dimension="_standarddimension_tree" overrideDimensionName="Tree"/>
    <writebackTable xmi:id="_writebacktable_factwb" name="FACTWB">
      <writebackAttribute xmi:id="_writebackattribute_node" column="_column_factwb_node" dimensionConnector="_dimensionconnector_tree"/>
      <writebackMeasure xmi:id="_writebackmeasure_value" column="_column_factwb_value" name="Value"/>
    </writebackTable>
    <measureGroups xmi:id="_measuregroup">
      <measures xsi:type="rolapmeas:SumMeasure" xmi:id="_summeasure_value" name="Value" formatString="#,##0" column="_column_fact_value"/>
    </measureGroups>
  </rolapcube:PhysicalCube>
</xmi:XMI>

Tutorial Zip ​

This file contains the data-tables as csv and the mapping as xmi file.

Download Zip File

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