I believe mostly how much code needs to be changed, which they are working towards slowly, but there is more overhead (memory / disk) associated with those larg

I believe mostly how much code needs to be changed, which they are working towards slowly, but there is more overhead (memory / disk) associated with those larger data types which are used everywhere: https://wiki.postgresql.org/wiki/FullTransactionId https://wiki.postgresql.org/wiki/FullTransactionId