Medie e Totali Mobili

Window Functions in Snowflake

Jake Roach

Field Data Engineer

Medie e Totali in Esecuzione

Output che mostra una finestra "scorrevole".

Medie e Totali "Mobili"

Output che mostra una media mobile.

Medie e Totali "Mobili"

Output che mostra un totale mobile.

Calcoli Mobili

SELECT
    ...

    AVG(<1>) OVER(
        PARTITION BY ...
        ORDER BY <2>

        -- Finestra tra X precedenti
        -- e Y successivi record


        ROWS BETWEEN <X> PRECEDING 
            AND <Y> FOLLOWING

    )
...

Specifica il numero di record prima e dopo la riga corrente

ROWS BETWEEN X PRECEDING AND Y FOLLOWING

Calcolo "mobile", non in esecuzione
Può ancora usare CURRENT ROW

<X>: # di righe da guardare indietro

<Y>: # di righe da guardare avanti

Creare una media mobile

SELECT
    member_id, workout_date, calories_burned,

    -- Crea una media mobile usando una finestra con l'allenamento precedente, 
    -- l'allenamento corrente e il successivo

    AVG(calories_burned) OVER(
        PARTITION BY member_id
        ORDER BY workout_date

        ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING

    ) AS moving_avg_cb

FROM FITNESS.workouts;

Creare una media mobile

             member_id  |  workout_date  |   calories_burned  |  moving_avg_cb  
            ----------- | -------------- | ------------------ | --------------- 
               m_192    |   2024-01-01   |         105        |      130.5      
               m_192    |   2024-01-03   |         156        |      110.0      
               m_192    |   2024-01-04   |          69        |      109.0      
               m_192    |   2024-01-10   |         102        |      120.0      
               m_192    |   2024-01-11   |         189        |      127.3     
               m_192    |   2024-01-12   |          91        |      145.0     
               m_192    |   2024-01-16   |         155        |      127.7      
               m_192    |   2024-01-19   |         137        |      133.7      
               m_192    |   2024-01-20   |         109        |      123.0      

               m_74     |   2024-02-10   |         374        |      385.0      
                                        ...

Informare i membri con totali mobili

SELECT
    member_id, workout_date, calories_burned,

    ...

    -- Usa CURRENT ROW per evitare "look ahead"
    SUM(calories_burned) OVER(
        PARTITION BY member_id
        ORDER BY workout_date

        ROWS BETWEEN 2 PRECEDING AND CURRENT ROW

    ) AS last_3_cb

FROM FITNESS.workouts;

Informare i membri con totali mobili

      member_id  |  workout_date  |   calories_burned  |  moving_avg_cb  |  last_3_cb
     ----------- | -------------- | ------------------ | --------------- | -----------
        m_192    |   2024-01-01   |         105        |      130.5      |     105
        m_192    |   2024-01-03   |         156        |      110.0      |     261
        m_192    |   2024-01-04   |          69        |      109.0      |     330
        m_192    |   2024-01-10   |         102        |      120.0      |     327
        m_192    |   2024-01-11   |         189        |      127.3      |     360
        m_192    |   2024-01-12   |          91        |      145.0      |     382
        m_192    |   2024-01-16   |         155        |      127.7      |     435
        m_192    |   2024-01-19   |         137        |      133.7      |     383
        m_192    |   2024-01-20   |         109        |      123.0      |     401

        m_74     |   2024-02-10   |         374        |      385.0      |     374
                                            ...

Ayo berlatih!

Window Functions in Snowflake