mark(dot)manley(at)tapad(dot)com writes:
> When using a foreign data wrapper from our 9.6.2 database to a MySQL 5.7
> database, we get inconsistent results.
My first thought is that you're looking at a bug in the mysql FDW,
probably incorrect pushdown of conditions to the mysql server. You
should enable logging on the mysql server and look at the queries
generated by the FDW, comparing those to EXPLAIN output to see which
conditions get checked locally as opposed to being sent to the remote.
If you can identify what the FDW is doing wrong, reporting that to
the FDW's authors might get some results. (I don't know if they
read this bugs list.)
regards, tom lane