Is there any way to determine a rough estimate of the size (on disk) of an index before creating it? The size of the table and each column are known. I am particularly interested in
GIN indexes. Also any information of how the sizes of different index types relate to each other is appreciated. Is there a general rule of thumb like a
GIN index is always bigger than a
B-TREE index? Or is it too dependent on the data size and distribution?
To clarify: i am not looking for a tool. I am happy to do it by hand.