When Should I Use ANY Instead of IN in WHERE Clauses?

Optimizing WHERE Clauses: ANY vs. IN

The choice between ANY and IN in SQL WHERE clauses often boils down to performance optimization. Both operators achieve the same fundamental goal – comparing a value against a set – but ANY provides greater flexibility and can, in certain scenarios, lead to performance gains.

Syntax Comparison

IN clauses are familiar to most SQL users:

• expression IN (subquery)
• expression IN (value1, value2, ...)

ANY offers similar functionality but with more options:

• expression operator ANY (subquery)
• expression operator ANY (array expression)

Choosing the Right Operator

ANY, a more modern addition to SQL, is versatile because it works with any comparison operator that yields a Boolean result. IN is essentially a specialized case of ANY.

The optimal choice hinges on the most convenient way to supply the comparison set: a list of values or an array. For data sourced directly from the database, a subquery or JOIN often proves more efficient. When dealing with extensive value lists passed from the application, arrays, unnest(), or JOINs are generally preferred for performance.

Working with = ANY and Arrays in PostgreSQL

PostgreSQL supports two array expression formats:

• Array constructor: ARRAY[1, 2, 3]
• Array literal: '{1, 2, 3}'

Explicit type casting (ARRAY[1, 2, 3]::numeric[] or '{1, 2, 3}'::bigint[]) prevents type-related errors.

Example: Ruby and Array Passing

For integer arrays in Ruby:

MyModel.where('id = ANY(ARRAY[?]::int[])', ids.map { |i| i })

Remember that the precise Ruby syntax for array handling may differ depending on the ORM framework in use.

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