Remarks

• The arguments columnName and value must come in pairs; otherwise an error is returned.
• columnName must belong to the specified table, or to a table that is related to table.
• If columnName refers to a column in a related table then it must be fully qualified; otherwise, an error is returned.

Using CONTAINS is more efficient than using a similar syntax using COUNTROWS and FILTER:

COUNTROWS ( 
    FILTER (
        table,
        columnName = value
    )
) > 0

A common pattern with CONTAINS is that used for a virtual relationship, which is better implemented using TREATAS or INTERSECT. The following code:

CALCULATE ( 
    [measure],
    FILTER ( 
        ALL ( targetTable[targetColumn] ),
        CONTAINS ( 
            VALUES ( sourceTable[sourceColumn] ),
            sourceTable[sourceColumn],
            targetTable[targetColumn]
        )
    )
)

can be better written using TREATAS:

CALCULATE ( 
    [measure],
    TREATAS ( 
        VALUES ( sourceTable[sourceColumn] ),
        targetTable[targetColumn]
    )
)

If TREATAS is not available, INTERSECT provide a second choice alternative:

CALCULATE ( 
    [measure],
    INTERSECT ( 
        ALL (  targetTable[targetColumn] ),
        VALUES ( sourceTable[sourceColumn] )
    )
)