3. Compass Entry Selection — Stacked Cartesian

In this step the Compass entry on which the Stacked widget will run is selected. In the Stacked flow, your entry must return at least three columns: X axis, Y value, and the categorical column that determines the stack category (Stack By).

Wizard route: /cartography/add/selectcompass

Prerequisite

Steps 1 (Cartesian) and 2 (Stacked* type) must be completed.

If there is no entry in Compass: → Compass

---

1. Compass Entry List Loads

When you enter the step, the Compass entry list loads automatically.

---

2. Entry Structure Suitable for Stacked

The Stacked flow requires your query to return a categorical column. SQL example:

-- Ideal query for Shift × Product stack column
SELECT
    shift,              -- X axis (CategoryAxis)
    product_code,       -- Stack By Column
    SUM(count) AS total_count  -- Y axis (NumericAxis)
FROM production_log
WHERE DATE(ts) = CURRENT_DATE
GROUP BY shift, product_code
ORDER BY shift, product_code;

Column	Role in Step 4
shift	X Axis Column (CategoryAxis)
product_code	Stack By Column
total_count	Y Axis Column (NumericAxis)

Stack By Category Cardinality

The number of unique values in the Stack By column directly equals the number of stack layers. 12+ categories cause clutter; the ideal range is 3-8 categories. Group as "Other" in SQL:

SELECT
    shift,
    CASE WHEN product_code IN (...top5...) THEN product_code
         ELSE 'Other' END AS product_group,
    SUM(count)
FROM ...

---

3. Data Sources Suitable for Stacked

Data Source	Suitability for Stacked	Notes
PostgreSQL / MSSQL / MySQL	✅ Ideal	Comes ready with GROUP BY x, stack_by
REST API	✅ Suitable	JSON response array structure must have x/y/stack_by
MQTT	⚠️ Limited	Snapshot returns a single row; not meaningful for stack
Excel Offline	✅ Suitable	The sheet must be in long format (shift, product, count)

---

4. Search Entry and Tag Filter

Action	Effect
Search box	Live filter on entry name + description
Tag filter	Filter icon at the top of the list
Clear	Removes all tag filters

Stacked Tag

Add a stacked tag on the Compass side for Stacked queries; when searching in Cartography, with the filter active, only entries with suitable structure appear.

---

5. Confirm the Entry

When an entry is clicked, the row is highlighted. Proceed with the Next button at the top right.

Proceeding Without Entry Selection

If no entry is selected, Next issues a warning: "Please select a Compass query first".

---

6. Excel Offline Sheet Selection

For an Excel entry, an additional sheet selection is requested.

Step	Description
1	Select the Excel entry
2	Select a sheet name from the opened sheet list
3	Next

---

7. Preview Run

When the Next button is pressed, the entry is run and the result is held in memory. The preview is prepared here so the Stack By column can be selected correctly in the next step.

---

8. Common Errors

Symptom	Possible Cause	Solution
Stack By dropdown is empty in Step 4	Query does not return a categorical column	Add GROUP BY in SQL and include the categorical column in the select list
Stack layers are too crowded	Stack By column has high cardinality	Group as "Other"; merge categories outside the top N
Y values do not aggregate	Query is row-based	Aggregate with SUM(...) GROUP BY

---

9. Next Step

→ 04 — Axis Config + Stack By