Today, I'd like to show you how you can use the same index for two different types of conditions. One that is using normal BTree indexing ( equal, less than, greater than ), and one that is using GIN/GiST index, for full text searching.
Today, Mattias|farm on IRC asked how to create primary key using HASH index. After some talk, he said that in some books it said that for “=" (equality) hash indexes are better.
So, I digged a bit deeper.