Calculating period-over-period changes

cubes:
  - name: month_over_month
    sql: |
      SELECT 1 AS value, '2024-01-01'::TIMESTAMP AS date UNION ALL
      SELECT 2 AS value, '2024-01-01'::TIMESTAMP AS date UNION ALL
      SELECT 3 AS value, '2024-02-01'::TIMESTAMP AS date UNION ALL
      SELECT 4 AS value, '2024-02-01'::TIMESTAMP AS date UNION ALL
      SELECT 5 AS value, '2024-03-01'::TIMESTAMP AS date UNION ALL
      SELECT 6 AS value, '2024-03-01'::TIMESTAMP AS date UNION ALL
      SELECT 7 AS value, '2024-04-01'::TIMESTAMP AS date UNION ALL
      SELECT 8 AS value, '2024-04-01'::TIMESTAMP AS date

    dimensions:
      - name: date
        sql: date
        type: time

    measures:
      - name: current_month_sum
        sql: value
        type: sum

      - name: previous_month_sum
        multi_stage: true
        sql: "{current_month_sum}"
        type: number
        time_shift:
          - interval: 1 month
            type: prior

      - name: month_over_month_ratio
        multi_stage: true
        sql: "{current_month_sum} / NULLIF({previous_month_sum}, 0)"
        type: number

cube(`month_over_month`, {
  sql: `
    SELECT 1 AS value, '2024-01-01'::TIMESTAMP AS date UNION ALL
    SELECT 2 AS value, '2024-01-01'::TIMESTAMP AS date UNION ALL
    SELECT 3 AS value, '2024-02-01'::TIMESTAMP AS date UNION ALL
    SELECT 4 AS value, '2024-02-01'::TIMESTAMP AS date UNION ALL
    SELECT 5 AS value, '2024-03-01'::TIMESTAMP AS date UNION ALL
    SELECT 6 AS value, '2024-03-01'::TIMESTAMP AS date UNION ALL
    SELECT 7 AS value, '2024-04-01'::TIMESTAMP AS date UNION ALL
    SELECT 8 AS value, '2024-04-01'::TIMESTAMP AS date
  `,

  dimensions: {
    date: {
      sql: `date`,
      type: `time`
    }
  },

  measures: {
    current_month_sum: {
      sql: `value`,
      type: `sum`
    },

    previous_month_sum: {
      multi_stage: true,
      sql: `${current_month_sum}`,
      type: `number`,
      time_shift: [{
        interval: `1 month`,
        type: `prior`
      }]
    },

    month_over_month_ratio: {
      multi_stage: true,
      sql: `${current_month_sum} / NULLIF(${previous_month_sum}, 0)`,
      type: `number`
    }
  }
})