Query Memory Limit Hard

What is the query memory limit hard as mentioned in the docs using query.memory.limit.hard .The default value is shown as 9223372036854775807B. What is the memory limit for this specidfied value in Gigabytes?

It's a server side property to put a global limit on how much managed memory any query over any database can consume. Whatever databases specify in their query.memory.limit properties is subject to that.

By default it's effectively unlimited.