Equality Filter in Spark Structured Streaming

I am writing a Spark Structured Streaming job and I have to filter on a string column.

When I am filtering on the long column it is able to filter(using below code):

arr =  arr.filter(col("epoch") > 1610913720)

But when I am doing on a string, data is not filtered:

arr =  arr.filter(col("id").equalTo("z12"))