Rearrange CustomScan API.

Make it work more like FDW plans do: instead of assuming that there are
expressions in a CustomScan plan node that the core code doesn't know
about, insist that all subexpressions that need planner attention be in
a "custom_exprs" list in the Plan representation.  (Of course, the
custom plugin can break the list apart again at executor initialization.)
This lets us revert the parts of the patch that exposed setrefs.c and
subselect.c processing to the outside world.

Also revert the GetSpecialCustomVar stuff in ruleutils.c; that concept
may work in future, but it's far from fully baked right now.

1 files changed, 0 insertions, 70 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index bf4e81f554a..24ade6cc201 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5493,26 +5493,6 @@ get_utility_query_def(Query *query, deparse_context *context)
 	}
 }
 
-/*
- * GetSpecialCustomVar
- *
- * If a custom-scan provider uses a special varnode, this function will be
- * called when deparsing; it should return an Expr node to be reversed-listed
- * in lieu of the special Var.
- */
-static Node *
-GetSpecialCustomVar(CustomScanState *css, Var *varnode, PlanState **child_ps)
-{
-	Assert(IsA(css, CustomScanState));
-	Assert(IS_SPECIAL_VARNO(varnode->varno));
-
-	if (!css->methods->GetSpecialCustomVar)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("%s does not support special varno reference",
-						css->methods->CustomName)));
-	return (Node *) css->methods->GetSpecialCustomVar(css, varnode, child_ps);
-}
 
 /*
  * Display a Var appropriately.
@@ -5542,8 +5522,6 @@ get_variable(Var *var, int levelsup, bool istoplevel, deparse_context *context)
 	int			netlevelsup;
 	deparse_namespace *dpns;
 	deparse_columns *colinfo;
-	PlanState  *child_ps = NULL;
-	Node	   *expr;
 	char	   *refname;
 	char	   *attname;
 
@@ -5568,29 +5546,6 @@ get_variable(Var *var, int levelsup, bool istoplevel, deparse_context *context)
 		colinfo = deparse_columns_fetch(var->varno, dpns);
 		attnum = var->varattno;
 	}
-	else if (IS_SPECIAL_VARNO(var->varno) &&
-			 IsA(dpns->planstate, CustomScanState) &&
-			 (expr = GetSpecialCustomVar((CustomScanState *) dpns->planstate,
-										 var, &child_ps)) != NULL)
-	{
-		deparse_namespace	save_dpns;
-
-		if (child_ps)
-			push_child_plan(dpns, child_ps, &save_dpns);
-		/*
-		 * Force parentheses because our caller probably assumed a Var is a
-		 * simple expression.
-		 */
-		if (!IsA(expr, Var))
-			appendStringInfoChar(buf, '(');
-		get_rule_expr((Node *) expr, context, true);
-		if (!IsA(expr, Var))
-			appendStringInfoChar(buf, ')');
-
-		if (child_ps)
-			pop_child_plan(dpns, &save_dpns);
-		return NULL;
-	}
 	else if (var->varno == OUTER_VAR && dpns->outer_tlist)
 	{
 		TargetEntry *tle;
@@ -5805,7 +5760,6 @@ get_name_for_var_field(Var *var, int fieldno,
 	AttrNumber	attnum;
 	int			netlevelsup;
 	deparse_namespace *dpns;
-	PlanState  *child_ps = NULL;
 	TupleDesc	tupleDesc;
 	Node	   *expr;
 
@@ -5880,30 +5834,6 @@ get_name_for_var_field(Var *var, int fieldno,
 		rte = rt_fetch(var->varno, dpns->rtable);
 		attnum = var->varattno;
 	}
-	else if (IS_SPECIAL_VARNO(var->varno) &&
-			 IsA(dpns->planstate, CustomScanState) &&
-			 (expr = GetSpecialCustomVar((CustomScanState *) dpns->planstate,
-										 var, &child_ps)) != NULL)
-	{
-		StringInfo		saved = context->buf;
-		StringInfoData	temp;
-		deparse_namespace save_dpns;
-
-		initStringInfo(&temp);
-		context->buf = &temp;
-
-		if (child_ps)
-			push_child_plan(dpns, child_ps, &save_dpns);
-		if (!IsA(expr, Var))
-			appendStringInfoChar(context->buf, '(');
-		get_rule_expr((Node *) expr, context, true);
-		if (!IsA(expr, Var))
-			appendStringInfoChar(context->buf, ')');
-		if (child_ps)
-			pop_child_plan(dpns, &save_dpns);
-		context->buf = saved;
-		return temp.data;
-	}
 	else if (var->varno == OUTER_VAR && dpns->outer_tlist)
 	{
 		TargetEntry *tle;