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ANY() equi-join condition

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Overview

The “field = ANY(...)” equality condition returns true if the equality comparison is true for any of the values in the ANY() expression.

For equi-join whose ON expression includes an ANY operator expression, Materialize provides an idiomatic SQL as an alternative to the ANY() expression.

Materialize and equi-join ON fieldX = ANY(<array|list|map>)

When evaluating an equi-join whose ON expression includes the ANY operator expression (i.e., ON fieldX = ANY(<array|list|map>)), Materialize performs a cross join, which can lead to a significant increase in memory usage. If possible, rewrite the query to perform an equi-join on the unnested values.

Idiomatic Materialize SQL

Idiomatic Materialize SQL: For equi-join whose ON expression includes the ANY operator expression (ON fieldX = ANY(<array|list|map>)), use UNNEST() in a Common Table Expression (CTE) to unnest the values and perform the equi-join on the unnested values. If the array/list/map contains duplicates, include DISTINCT to remove duplicates.
Materialize SQL

If no duplicates exist in the unnested field: Use a Common Table Expression (CTE) to UNNEST() the array of values and perform the equi-join on the unnested values.

-- array_field contains no duplicates.--

WITH my_expanded_values AS
(SELECT UNNEST(array_field) AS fieldZ FROM tableB)
SELECT a.fieldA, ...
FROM tableA a
JOIN my_expanded_values t ON a.fieldZ = t.fieldZ
;

Duplicates may exist in the unnested field: Use a Common Table Expression (CTE) to DISTINCT UNNEST() the array of values and perform the equi-join on the unnested values.

-- array_field may contain duplicates.--

WITH my_expanded_values AS
(SELECT DISTINCT UNNEST(array_field) AS fieldZ FROM tableB)
SELECT a.fieldA, ...
FROM tableA a
JOIN my_expanded_values t ON a.fieldZ = t.fieldZ
;
Anti-pattern ❌

Avoid the use of ANY(...) function for equi-join conditions.

-- Anti-pattern. Avoid. --
SELECT a.fieldA, ...
FROM tableA a, tableB b
WHERE a.fieldZ = ANY(b.array_field) -- Anti-pattern. Avoid.
;

Examples

NOTE: The example data can be found in the Appendix.

Find orders with any sales items

Using idiomatic Materialize SQL, the following example finds orders that contain any of the sales items for the week of the order. That is, the example uses a CTE to UNNEST() (or DISTINCTUNNEST()) the items field from the sales_items table, and then performs an equi-join with the orders table on the unnested values.
Materialize SQL ✅

If no duplicates in the unnested field

-- sales_items.items contains no duplicates. --

WITH individual_sales_items AS
(SELECT unnest(items) as item, week_of FROM sales_items)
SELECT s.week_of, o.order_id, o.item, o.quantity
FROM orders o
JOIN individual_sales_items s ON o.item = s.item
WHERE date_trunc('week', o.order_date) = s.week_of
ORDER BY s.week_of, o.order_id, o.item, o.quantity
;

To omit duplicates that may exist in the unnested field

-- sales_items.items may contains duplicates --

WITH individual_sales_items AS
(SELECT DISTINCT unnest(items) as item, week_of FROM sales_items)
SELECT s.week_of, o.order_id, o.item, o.quantity
FROM orders o
JOIN individual_sales_items s ON o.item = s.item
WHERE date_trunc('week', o.order_date) = s.week_of
ORDER BY s.week_of, o.order_id, o.item, o.quantity
;
Anti-pattern ❌

Avoid the use of ANY() for the equi-join condition.

-- Anti-pattern. Avoid. --
SELECT s.week_of, o.order_id, o.item, o.quantity
FROM orders o
JOIN sales_items s ON o.item = ANY(s.items)
WHERE date_trunc('week', o.order_date) = s.week_of
ORDER BY s.week_of, o.order_id, o.item, o.quantity
;

See also

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