introduce safe function PrelLastChild(), fixes for get_range_by_idx()

Author: funbringer

src/hooks.c

@@ -227,7 +227,7 @@ pathman_rel_pathlist_hook(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTb
 		rte->inh = true; /* we must restore 'inh' flag! */
 
 		children = PrelGetChildrenArray(prel);
-		ranges = list_make1_irange(make_irange(0, PrelChildrenCount(prel) - 1, false));
+		ranges = list_make1_irange(make_irange(0, PrelLastChild(prel), false));
 
 		/* Make wrappers over restrictions and collect final rangeset */
 		InitWalkerContext(&context, prel, NULL, false);

src/nodes_common.c

@@ -502,7 +502,7 @@ rescan_append_common(CustomScanState *node)
 	Assert(prel);
 
 	/* First we select all available partitions... */
-	ranges = list_make1_irange(make_irange(0, PrelChildrenCount(prel) - 1, false));
+	ranges = list_make1_irange(make_irange(0, PrelLastChild(prel), false));
 
 	InitWalkerContext(&scan_state->wcxt, prel, econtext, false);
 	foreach (lc, scan_state->custom_exprs)

src/pg_pathman.c

@@ -320,7 +320,7 @@ handle_modification_query(Query *parse)
 		return;
 
 	/* Parse syntax tree and extract partition ranges */
-	ranges = list_make1_irange(make_irange(0, PrelChildrenCount(prel) - 1, false));
+	ranges = list_make1_irange(make_irange(0, PrelLastChild(prel), false));
 	expr = (Expr *) eval_const_expressions(NULL, parse->jointree->quals);
 	if (!expr)
 		return;
@@ -680,7 +680,7 @@ walk_expr_tree(Expr *expr, WalkerContext *context)
 			result->orig = (const Node *) expr;
 			result->args = NIL;
 			result->rangeset = list_make1_irange(
-						make_irange(0, PrelChildrenCount(context->prel) - 1, true));
+						make_irange(0, PrelLastChild(context->prel), true));
 			result->paramsel = 1.0;
 			return result;
 	}
@@ -839,7 +839,7 @@ create_partitions_internal(Oid relid, Datum value, Oid value_type)
 
 			/* Read max & min range values from PartRelationInfo */
 			min_rvalue = prel->ranges[0].min;
-			max_rvalue = prel->ranges[PrelChildrenCount(prel) - 1].max;
+			max_rvalue = prel->ranges[PrelLastChild(prel)].max;
 
 			/* If this is a *date type*, cast 'range_interval' to INTERVAL */
 			if (is_date_type_internal(value_type))
@@ -1183,9 +1183,7 @@ handle_binary_opexpr(WalkerContext *context, WrapperNode *result,
 			elog(ERROR, "Unknown partitioning type %u", prel->parttype);
 	}
 
-	result->rangeset = list_make1_irange(make_irange(0,
-													 PrelChildrenCount(prel) - 1,
-													 true));
+	result->rangeset = list_make1_irange(make_irange(0, PrelLastChild(prel), true));
 	result->paramsel = 1.0;
 }
 
@@ -1211,9 +1209,7 @@ handle_binary_opexpr_param(const PartRelationInfo *prel,
 	tce = lookup_type_cache(vartype, TYPECACHE_BTREE_OPFAMILY);
 	strategy = get_op_opfamily_strategy(expr->opno, tce->btree_opf);
 
-	result->rangeset = list_make1_irange(make_irange(0,
-													 PrelChildrenCount(prel) - 1,
-													 true));
+	result->rangeset = list_make1_irange(make_irange(0, PrelLastChild(prel), true));
 
 	if (strategy == BTEqualStrategyNumber)
 	{
@@ -1311,7 +1307,7 @@ handle_const(const Const *c, WalkerContext *context)
 	if (!context->for_insert)
 	{
 		result->rangeset = list_make1_irange(make_irange(0,
-														 PrelChildrenCount(prel) - 1,
+														 PrelLastChild(prel),
 														 true));
 		result->paramsel = 1.0;
 
@@ -1382,9 +1378,7 @@ handle_opexpr(const OpExpr *expr, WalkerContext *context)
 		}
 	}
 
-	result->rangeset = list_make1_irange(make_irange(0,
-													 PrelChildrenCount(prel) - 1,
-													 true));
+	result->rangeset = list_make1_irange(make_irange(0, PrelLastChild(prel), true));
 	result->paramsel = 1.0;
 	return result;
 }
@@ -1456,7 +1450,7 @@ handle_boolexpr(const BoolExpr *expr, WalkerContext *context)
 
 	if (expr->boolop == AND_EXPR)
 		result->rangeset = list_make1_irange(make_irange(0,
-														 PrelChildrenCount(prel) - 1,
+														 PrelLastChild(prel),
 														 false));
 	else
 		result->rangeset = NIL;
@@ -1479,7 +1473,7 @@ handle_boolexpr(const BoolExpr *expr, WalkerContext *context)
 				break;
 			default:
 				result->rangeset = list_make1_irange(make_irange(0,
-																 PrelChildrenCount(prel) - 1,
+																 PrelLastChild(prel),
 																 false));
 				break;
 		}
@@ -1581,9 +1575,7 @@ handle_arrexpr(const ScalarArrayOpExpr *expr, WalkerContext *context)
 		result->paramsel = DEFAULT_INEQ_SEL;
 
 handle_arrexpr_return:
-	result->rangeset = list_make1_irange(make_irange(0,
-													 PrelChildrenCount(prel) - 1,
-													 true));
+	result->rangeset = list_make1_irange(make_irange(0, PrelLastChild(prel), true));
 	return result;
 }
 

src/pl_funcs.c

@@ -11,6 +11,7 @@
 #include "pathman.h"
 #include "init.h"
 #include "utils.h"
+#include "relation_info.h"
 
 #include "access/htup_details.h"
 #include "access/nbtree.h"
@@ -289,17 +290,23 @@ get_range_by_idx(PG_FUNCTION_ARGS)
 	prel = get_pathman_relation_info(parent_oid);
 	shout_if_prel_is_invalid(parent_oid, prel, PT_RANGE);
 
-	if (((uint32) abs(idx)) >= PrelChildrenCount(prel))
+	/* Now we have to deal with 'idx' */
+	if (idx < -1)
+	{
+		elog(ERROR, "Negative indices other than -1 (last partition) are not allowed");
+	}
+	else if (idx == -1 && PrelChildrenCount(prel) > 0)
+	{
+		idx = PrelLastChild(prel);
+	}
+	else if (((uint32) abs(idx)) >= PrelChildrenCount(prel))
+	{
 		elog(ERROR, "Partition #%d does not exist (total amount is %u)",
 			 idx, PrelChildrenCount(prel));
+	}
 
 	ranges = PrelGetRangesArray(prel);
 
-	if (idx == -1)
-		idx = PrelChildrenCount(prel) - 1;
-	else if (idx < -1)
-		elog(ERROR, "Negative indices other than -1 (last partition) are not allowed");
-
 	elems[0] = ranges[idx].min;
 	elems[1] = ranges[idx].max;
 
@@ -343,7 +350,7 @@ get_max_range_value(PG_FUNCTION_ARGS)
 
 	ranges = PrelGetRangesArray(prel);
 
-	PG_RETURN_DATUM(ranges[PrelChildrenCount(prel) - 1].max);
+	PG_RETURN_DATUM(ranges[PrelLastChild(prel)].max);
 }
 
 /*

src/relation_info.h

@@ -107,13 +107,25 @@ typedef enum
  * PartRelationInfo field access macros.
  */
 
-#define PrelGetChildrenArray(prel) ( (prel)->children )
+#define PrelGetChildrenArray(prel)	( (prel)->children )
 
-#define PrelGetRangesArray(prel) ( (prel)->ranges )
+#define PrelGetRangesArray(prel)	( (prel)->ranges )
 
-#define PrelChildrenCount(prel) ( (prel)->children_count )
+#define PrelChildrenCount(prel)		( (prel)->children_count )
 
-#define PrelIsValid(prel) ( (prel) && (prel)->valid )
+#define PrelIsValid(prel)			( (prel) && (prel)->valid )
+
+inline static uint32
+PrelLastChild(const PartRelationInfo *prel)
+{
+	Assert(PrelIsValid(prel));
+
+	if (PrelChildrenCount(prel) == 0)
+		elog(ERROR, "pg_pathman's cache entry for relation %u has 0 children",
+			 prel->key);
+
+	return PrelChildrenCount(prel) - 1; /* last partition */
+}
 
 
 const PartRelationInfo *refresh_pathman_relation_info(Oid relid,