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3. Compass Record Selection — Range Column

In this step, the Compass record that the Range Column widget will use is selected. Your record must return at least three columns: X axis, Low value, and High value. Optionally, a categorical fourth column can be added for Color By.

Wizard route: /cartography/add/selectcompass

Prerequisite

Steps 1 (Cartesian) and 2 (Range Column) must be completed.

→ 02 — Chart Type Selection

1. Compass Record List

Query selection screen

2. Record Structure Suitable for Range Column

-- Daily min/max temperature (Color By: shift)
SELECT
    day,                              -- X axis
    MIN(temperature) AS temp_min,     -- Low Value Column
    MAX(temperature) AS temp_max,     -- High Value Column
    shift AS shift_color              -- Color By Column (optional)
FROM sensor_log
WHERE day >= CURRENT_DATE - INTERVAL '30 days'
GROUP BY day, shift
ORDER BY day;
Column Role in Step 4 Type
day X Axis Column (DateTimeAxis) DATE / TIMESTAMP
temp_min Low Value Column NUMERIC
temp_max High Value Column NUMERIC
shift_color Color By Column (optional) TEXT

Low ≤ High

Low Value must be less than High Value. Otherwise the bar renders inverted or appears empty. Use SQL LEAST / GREATEST to guarantee this:

SELECT
    day,
    LEAST(val1, val2) AS temp_min,
    GREATEST(val1, val2) AS temp_max
FROM ...

3. Data Sources Suitable for Range Column

Data Source Suitability for Range Column Notes
PostgreSQL / MSSQL / MySQL ✅ Ideal Practical with MIN/MAX aggregate
REST API ✅ Suitable JSON response with low/high keys
MQTT ❌ Limited Snapshot is a single row; producing a range is meaningless
Excel Offline ✅ Suitable Low/high columns must be in separate columns in the sheet

4. Record Search and Tag Filter

Action Effect
Search box Instant filter on record name + description
Tag filter Select tags from the filter icon
Clear Clear filters

Range Tag

Use range, min-max tags in Compass for Range Column queries.

5. Confirm the Record

Click on a record to highlight the row. Proceed with the Next button at the top right.

Compass record selected

Proceeding Without Selecting a Record

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

6. Excel Offline Sheet Selection

If an Excel record is selected, a Sheet dropdown appears below it. Select a sheet then click Next.

7. Preview Execution

When the Next button is pressed, the record is executed and the result is kept in memory.

8. Common Errors

Symptom Possible Cause Solution
Low/High dropdown empty in Step 4 Query returns only one numeric column Add MIN(...) AS low, MAX(...) AS high
No column in Color By dropdown No categorical column in query Add a TEXT column like shift, product_code
Bars appear inverted Low > High Protect with LEAST / GREATEST

9. Next Step

→ 04 — Axis Config + Low/High