diff options
Diffstat (limited to 'contrib/postgres_fdw/deparse.c')
| -rw-r--r-- | contrib/postgres_fdw/deparse.c | 89 |
1 files changed, 57 insertions, 32 deletions
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c index 81cb2b447d8..697de60dfe5 100644 --- a/contrib/postgres_fdw/deparse.c +++ b/contrib/postgres_fdw/deparse.c @@ -17,11 +17,12 @@ * We do not consider that it is ever safe to send COLLATE expressions to * the remote server: it might not have the same collation names we do. * (Later we might consider it safe to send COLLATE "C", but even that would - * fail on old remote servers.) An expression is considered safe to send only - * if all collations used in it are traceable to Var(s) of the foreign table. - * That implies that if the remote server gets a different answer than we do, - * the foreign table's columns are not marked with collations that match the - * remote table's columns, which we can consider to be user error. + * fail on old remote servers.) An expression is considered safe to send + * only if all operator/function input collations used in it are traceable to + * Var(s) of the foreign table. That implies that if the remote server gets + * a different answer than we do, the foreign table's columns are not marked + * with collations that match the remote table's columns, which we can + * consider to be user error. * * Portions Copyright (c) 2012-2015, PostgreSQL Global Development Group * @@ -69,9 +70,12 @@ typedef struct foreign_glob_cxt */ typedef enum { - FDW_COLLATE_NONE, /* expression is of a noncollatable type */ + FDW_COLLATE_NONE, /* expression is of a noncollatable type, or + * it has default collation that is not + * traceable to a foreign Var */ FDW_COLLATE_SAFE, /* collation derives from a foreign Var */ - FDW_COLLATE_UNSAFE /* collation derives from something else */ + FDW_COLLATE_UNSAFE /* collation is non-default and derives from + * something other than a foreign Var */ } FDWCollateState; typedef struct foreign_loc_cxt @@ -272,13 +276,24 @@ foreign_expr_walker(Node *node, else { /* Var belongs to some other table */ - if (var->varcollid != InvalidOid && - var->varcollid != DEFAULT_COLLATION_OID) - return false; - - /* We can consider that it doesn't set collation */ - collation = InvalidOid; - state = FDW_COLLATE_NONE; + collation = var->varcollid; + if (collation == InvalidOid || + collation == DEFAULT_COLLATION_OID) + { + /* + * It's noncollatable, or it's safe to combine with a + * collatable foreign Var, so set state to NONE. + */ + state = FDW_COLLATE_NONE; + } + else + { + /* + * Do not fail right away, since the Var might appear + * in a collation-insensitive context. + */ + state = FDW_COLLATE_UNSAFE; + } } } break; @@ -288,16 +303,16 @@ foreign_expr_walker(Node *node, /* * If the constant has nondefault collation, either it's of a - * non-builtin type, or it reflects folding of a CollateExpr; - * either way, it's unsafe to send to the remote. + * non-builtin type, or it reflects folding of a CollateExpr. + * It's unsafe to send to the remote unless it's used in a + * non-collation-sensitive context. */ - if (c->constcollid != InvalidOid && - c->constcollid != DEFAULT_COLLATION_OID) - return false; - - /* Otherwise, we can consider that it doesn't set collation */ - collation = InvalidOid; - state = FDW_COLLATE_NONE; + collation = c->constcollid; + if (collation == InvalidOid || + collation == DEFAULT_COLLATION_OID) + state = FDW_COLLATE_NONE; + else + state = FDW_COLLATE_UNSAFE; } break; case T_Param: @@ -305,14 +320,14 @@ foreign_expr_walker(Node *node, Param *p = (Param *) node; /* - * Collation handling is same as for Consts. + * Collation rule is same as for Consts and non-foreign Vars. */ - if (p->paramcollid != InvalidOid && - p->paramcollid != DEFAULT_COLLATION_OID) - return false; - - collation = InvalidOid; - state = FDW_COLLATE_NONE; + collation = p->paramcollid; + if (collation == InvalidOid || + collation == DEFAULT_COLLATION_OID) + state = FDW_COLLATE_NONE; + else + state = FDW_COLLATE_UNSAFE; } break; case T_ArrayRef: @@ -348,6 +363,8 @@ foreign_expr_walker(Node *node, 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; } @@ -393,6 +410,8 @@ foreign_expr_walker(Node *node, 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; } @@ -434,6 +453,8 @@ foreign_expr_walker(Node *node, 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; } @@ -483,7 +504,7 @@ foreign_expr_walker(Node *node, /* * RelabelType must not introduce a collation not derived from - * an input foreign Var. + * an input foreign Var (same logic as for a real function). */ collation = r->resultcollid; if (collation == InvalidOid) @@ -491,6 +512,8 @@ foreign_expr_walker(Node *node, 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; } @@ -540,7 +563,7 @@ foreign_expr_walker(Node *node, /* * ArrayExpr must not introduce a collation not derived from - * an input foreign Var. + * an input foreign Var (same logic as for a function). */ collation = a->array_collid; if (collation == InvalidOid) @@ -548,6 +571,8 @@ foreign_expr_walker(Node *node, 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; } |