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-rw-r--r--contrib/postgres_fdw/deparse.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index 8f4d8a5..d7235a5 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -3624,13 +3624,12 @@ appendOrderByClause(List *pathkeys, bool has_final_sort,
{
ListCell *lcell;
int nestlevel;
- const char *delim = " ";
StringInfo buf = context->buf;
+ bool gotone = false;
/* Make sure any constants in the exprs are printed portably */
nestlevel = set_transmission_modes();
- appendStringInfoString(buf, " ORDER BY");
foreach(lcell, pathkeys)
{
PathKey *pathkey = lfirst(lcell);
@@ -3664,6 +3663,26 @@ appendOrderByClause(List *pathkeys, bool has_final_sort,
em_expr = em->em_expr;
/*
+ * If the member is a Const expression then we needn't add it to the
+ * ORDER BY clause. This can happen in UNION ALL queries where the
+ * union child targetlist has a Const. Adding these would be
+ * wasteful, but also, for INT columns, an integer literal would be
+ * seen as an ordinal column position rather than a value to sort by.
+ * deparseConst() does have code to handle this, but it seems less
+ * effort on all accounts just to skip these for ORDER BY clauses.
+ */
+ if (IsA(em_expr, Const))
+ continue;
+
+ if (!gotone)
+ {
+ appendStringInfoString(buf, " ORDER BY ");
+ gotone = true;
+ }
+ else
+ appendStringInfoString(buf, ", ");
+
+ /*
* Lookup the operator corresponding to the strategy in the opclass.
* The datatype used by the opfamily is not necessarily the same as
* the expression type (for array types for example).
@@ -3677,7 +3696,6 @@ appendOrderByClause(List *pathkeys, bool has_final_sort,
pathkey->pk_strategy, em->em_datatype, em->em_datatype,
pathkey->pk_opfamily);
- appendStringInfoString(buf, delim);
deparseExpr(em_expr, context);
/*
@@ -3687,7 +3705,6 @@ appendOrderByClause(List *pathkeys, bool has_final_sort,
appendOrderBySuffix(oprid, exprType((Node *) em_expr),
pathkey->pk_nulls_first, context);
- delim = ", ";
}
reset_transmission_modes(nestlevel);
}