IN vs. ANY in PostgreSQL: Which Operator Should You Choose?

PostgreSQL’s IN and ANY operators: Which one to choose?

PostgreSQL provides two structures, IN and ANY, which are commonly used to compare values ​​with sets. While the logical functionality of the two structures is essentially the same (both test set membership), they have subtle differences in syntax and performance.

Grammar Variations

IN has two syntax variants:

• IN (set): A set of values ​​enclosed in parentheses.
• IN (value1, value2, ...) Value: A comma-separated list of values.

ANY also has two grammatical variants:

• ANY (set) operator = value: Takes a set as the left operand and compares it to a value using the specified operator (=, >, <, etc.).
• ANY (array) scalar value: Takes an array (not a collection) as the left operand and compares it to a scalar value using the = operator.

Use Cases

• List of values: IN (value1, value2, ...) compares a column to a comma-separated list of values. This is useful when the number of values ​​is small.
• Collection Membership: IN (set) Checks whether a column is a member of the given set. This is equivalent to = ANY (set).
• Array comparison: ANY (array) Compares a column to an array. It can be used to check if a column contains any element in the array.

Performance Notes

In general, IN (collection) and ANY (collection) perform similarly, using an index scan if available. However, ANY (array) uses a sequential scan of the array, which may be less efficient for large arrays.

Comparison with = ANY (set)

Although IN (set) and = ANY (set) are logically equivalent, in some cases they may result in different query plans. Using IN forces PostgreSQL to create a temporary table for the collection, which may add overhead.

Versatility

ANY is more general than IN because it can be used with various operators (not just =). For example, you can use ANY with LIKE to check for pattern matching.

Exclude

To find rows that are not in a set, use NOT (column = ANY (set)). Alternatively, you can use ALL for this purpose.

NULL value

By default, rows with NULL values ​​are not compared via IN or ANY. To include NULL values, you can use IS NOT TRUE with a comparison.

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