# Compute a moving average Shape / table A variant of [Calculate across rows](https://meridian.online/operations/calculate-across-rows). Aggregate over a window of a fixed number of rows, or a span of time, that slides along with the current row. Page: ## Status Runs as a SQL step. arcform carries it as a `sql:` step today. ## The DuckDB step average over a sliding window of three rows and over the last seven days It reads the `orders` table the proofs share. Create it first: ```sql CREATE TABLE orders AS SELECT * FROM (VALUES (1, 'Alice Ng', 'north', DATE '2026-01-03', 120.00, 'widget', 'a|b', '{"channel":"web","items":[1,2]}'), (2, 'alice ng', 'north', DATE '2026-01-05', 80.50, 'gadget', 'b', '{"channel":"shop","items":[3]}'), (3, 'Bob Okafor', 'south', DATE '2026-01-05', 300.00, 'widget', 'a|c', '{"channel":"web","items":[4,5,6]}'), (4, 'Carla Díaz', 'east', DATE '2026-01-09', NULL, 'gizmo', NULL, '{"channel":"web","items":[]}'), (5, 'Bob Okafor', 'south', DATE '2026-01-12', 45.25, 'gadget', 'c', '{"channel":"phone","items":[7]}'), (6, 'Dev Patel', 'west', DATE '2026-01-12', 510.00, 'widget', 'a', '{"channel":"web","items":[8,9]}'), (7, 'Carla Diaz', 'east', DATE '2026-01-20', 99.99, 'gizmo', 'b|c', '{"channel":"shop","items":[10]}'), (8, 'Dev Patel', 'west', DATE '2026-02-02', 510.00, 'widget', 'a', '{"channel":"web","items":[8,9]}'), (9, 'Eve Larsen', NULL, DATE '2026-02-03', 15.00, 'gadget', NULL, '{"channel":"web","items":[11]}'), (10, 'Alice Ng', 'north', DATE '2026-02-10', 220.00, 'gizmo', 'a|b|c', '{"channel":"phone","items":[12,13]}') ) t(order_id, customer, region, order_date, amount, product, tags, meta); ``` Then run the statement: ```sql CREATE TEMP TABLE result AS SELECT order_id, order_date, amount, round(avg(amount) OVER (ORDER BY order_date, order_id ROWS BETWEEN 2 PRECEDING AND CURRENT ROW), 4) AS avg_3_rows, round(avg(amount) OVER (ORDER BY order_date RANGE BETWEEN INTERVAL 6 DAYS PRECEDING AND CURRENT ROW), 4) AS avg_7_days FROM orders WHERE amount IS NOT NULL; SELECT * FROM result ORDER BY order_date, order_id; SELECT CASE WHEN ((SELECT list(avg_3_rows ORDER BY order_date, order_id) FROM result) = [120.0, 100.25, 166.8333, 141.9167, 285.0833, 218.4133, 373.33, 208.33, 248.3333] AND (SELECT list(avg_7_days ORDER BY order_date, order_id) FROM result) = [120.0, 166.8333, 166.8333, 277.625, 277.625, 99.99, 510.0, 262.5, 220.0]) THEN 'as expected' ELSE error('the three-row and seven-day moving averages were not the expected values') END AS verdict; ``` It needs nothing installed beyond DuckDB itself. ## What other tools call it Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3). - EasyMorph: [`Sliding aggregation`](https://help.easymorph.com/doku.php?id=transformations:slidingaggregation) (read 2026-09-27) - KNIME Analytics Platform: [`Moving Aggregator`](https://api.hub.knime.com/nodes/*JKPnK49gCJ_6tVwe?details=full) (read 2026-09-27) - KNIME Analytics Platform: [`Moving Average`](https://api.hub.knime.com/nodes/*i6a4eZBqe7EBhz9G?details=full) (read 2026-09-27) - Apache NiFi: [`AttributeRollingWindow`](https://nifi.apache.org/components/org.apache.nifi.processors.stateful.analysis.AttributeRollingWindow/) (read 2026-09-27) - Polars: [`DataFrame.rolling`](https://docs.pola.rs/api/python/stable/reference/dataframe/modify_select.html) (read 2026-09-27) - Polars: [`Expr.ewm_mean`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.ewm_mean_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.ewm_std`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.ewm_sum`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.ewm_sum_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.ewm_var`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling`](https://docs.pola.rs/api/python/stable/reference/expressions/window.html) (read 2026-09-27) - Polars: [`Expr.rolling_kurtosis`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_map`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_max`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_max_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_mean`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_mean_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_median`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_median_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_min`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_min_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_quantile`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_quantile_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_rank`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_rank_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_skew`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_std`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_std_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_sum`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_sum_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_var`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`Expr.rolling_var_by`](https://docs.pola.rs/api/python/stable/reference/expressions/computation.html) (read 2026-09-27) - Polars: [`rolling_corr`](https://docs.pola.rs/api/python/stable/reference/expressions/functions.html) (read 2026-09-27) - Polars: [`rolling_cov`](https://docs.pola.rs/api/python/stable/reference/expressions/functions.html) (read 2026-09-27) - RapidMiner Studio: [`Moving Average Filter`](https://docs.rapidminer.com/latest/studio/operators/modeling/time_series/transformation/moving_average_filter.html) (read 2026-09-27) - Tableau Prep: [`Moving Calculation`](https://help.tableau.com/current/prep/en-us/prep_multirow_calculations.htm) (read 2026-09-27) - Trifacta: [`ROLLINGAVERAGE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGCOUNTA Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGKTHLARGEST Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGKTHLARGESTUNIQUE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGLIST Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMAX Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMAXDATE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMIN Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMINDATE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMODE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGMODEDATE Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGSTDEV Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGSTDEVSAMP Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGSUM Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGVAR Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - Trifacta: [`ROLLINGVARSAMP Function`](https://help.alteryx.com/aac/en/trifacta-classic/wrangle-language/window-functions.html) (read 2026-09-27) - VisiData: [`addcol-window`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/features/window.py#L63) (read 2026-09-23)