On Wed, Sep 23, 2015 at 7:29 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> Removing that entirely would be quite incorrect, because then you'd be > lying to the parent node about what collation your node outputs. > Yes. I too thought so and thus wanted to fix that code block by considering the default collation. > > After thinking a bit more about the existing special case for non-foreign > Vars, I wonder if what we should do is change these code blocks to look > like > > collation = r->resultcollid; > if (collation == InvalidOid) > state = FDW_COLLATE_NONE; > else if (inner_cxt.state == FDW_COLLATE_SAFE && > collation == inner_cxt.collation) > state = FDW_COLLATE_SAFE; > + else if (collation == DEFAULT_COLLATION_OID) > + state = FDW_COLLATE_NONE; > else > state = FDW_COLLATE_UNSAFE; > > That is, only explicit introduction of a non-default collation causes > a subexpression to get labeled FDW_COLLATE_UNSAFE. Default collations > would lose out when getting merged with a nondefault collation from a > foreign Var, so they should work all right. > Agree. I had suggested similar changes in approach (2) but you put that check at exact required place. > regards, tom lane > -- Jeevan B Chalke Principal Software Engineer, Product Development EnterpriseDB Corporation The Enterprise PostgreSQL Company
