Re: Getting sorted data from foreign server for merge join

collations arising from a foreign table's var are considered to be safer (FDW_COLLATE_SAFE) to push down to the foreign server , since they are either local default collation or are assumed to be same on foreign and local server as per user declaration. The onus of making that sure is on the user who declares particular collation for a foreign table var. As said upthread, different glibc implementations can cause collation ordering mismatch, this patch will be susceptible to the same problem as master/standby problem.