Fix overly-enthusiastic Assert in printing of Param reference expressions.

A NestLoopParam's value can only be a Var or Aggref, but this isn't the
case in general for SubPlan parameters, so print_parameter_expr had better
be prepared to cope.  Brain fade in my recent patch to print the referenced
expression instead of just printing $N for PARAM_EXEC Params.  Per report
from Pavel Stehule.

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index d4279c0f4e546fcf50435fea7c7e713f45068d50..a5cc48b47cc7fcbef32b3248906a59983a63a536 100644 (file)
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -4368,6 +4368,7 @@ print_parameter_expr(Node *expr, ListCell *ancestor_cell,
 {
    deparse_namespace save_dpns;
    bool        save_varprefix;
+   bool        need_paren;
 
    /* Switch attention to the ancestor plan node */
    push_ancestor_plan(dpns, ancestor_cell, &save_dpns);
@@ -4380,13 +4381,21 @@ print_parameter_expr(Node *expr, ListCell *ancestor_cell,
    context->varprefix = true;
 
    /*
-    * We don't need to add parentheses because a Param's expansion is
-    * (currently) always a Var or Aggref.
+    * A Param's expansion is typically a Var, Aggref, or upper-level Param,
+    * which wouldn't need extra parentheses.  Otherwise, insert parens to
+    * ensure the expression looks atomic.
     */
-   Assert(IsA(expr, Var) || IsA(expr, Aggref));
+   need_paren = !(IsA(expr, Var) ||
+                  IsA(expr, Aggref) ||
+                  IsA(expr, Param));
+   if (need_paren)
+       appendStringInfoChar(context->buf, '(');
 
    get_rule_expr(expr, context, false);
 
+   if (need_paren)
+       appendStringInfoChar(context->buf, ')');
+
    context->varprefix = save_varprefix;
 
    pop_ancestor_plan(dpns, &save_dpns);