UPDATE :

You can now use the LIKE keyword to do text searches in Azure Cosmos DB SQL (core) API!

EXAMPLE:

SELECT *
FROM c
WHERE c.description LIKE "%cereal%"

OLD Answer:

This can be achieved in 2 ways

(i) Currently Azure Cosmosdb supports the CONTAINS, STARTSWITH, and ENDSWITH built-in functions which are equivalent to LIKE.

The keyword for LIKE in Cosmosdb is Contains .

SELECT * FROM c WHERE CONTAINS(c.pi, '09')

So, in your case if you want to match the pattern 09%001, you need to use:

SELECT * FROM c WHERE STARTSWITH(c.pi, '09') AND ENDSWITH(c.pi, '001')

(ii) As 404 mentioned, Use SQL API User Defined Functions which supports regex :

function executeRegex(str, pattern) {
    let regex=RegExp(pattern);
    return regex.test(str);
}

SELECT udf.EXECUTE_REGEX("foobar", ".*bar")