Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> So here we go. The patch does a very simple thing - it uses TABLESAMPLE
> to collect/transfer just a small sample from the remote node, saving
> both CPU and network.
This is great if the remote end has TABLESAMPLE, but pre-9.5 servers
don't, and postgres_fdw is supposed to still work with old servers.
So you need some conditionality for that.
regards, tom lane