Global Nested Loop Join Optimization

The global nested loop join execution has been optimized.
We replaced the replication-based global Nested Loop join by a prefetch-based algorithms that just replicates the required rows and columns (global join) using standard global join constructs.

As a result. the new global join execution is faster, more stable and can better handle complex joins.
In particular, global between joins, complex mixed join and self-joins benefit from this optimization.