acquire suitable lock in append_child_relation()

Author: funbringer

src/hooks.c

@@ -29,6 +29,7 @@
 #include "catalog/pg_authid.h"
 #include "miscadmin.h"
 #include "optimizer/cost.h"
+#include "optimizer/prep.h"
 #include "optimizer/restrictinfo.h"
 #include "rewrite/rewriteManip.h"
 #include "utils/typcache.h"
@@ -290,6 +291,7 @@ pathman_rel_pathlist_hook(PlannerInfo *root,
 	if ((prel = get_pathman_relation_info(rte->relid)) != NULL)
 	{
 		Relation		parent_rel;				/* parent's relation (heap) */
+		PlanRowMark	   *parent_rowmark;			/* parent's rowmark */
 		Oid			   *children;				/* selected children oids */
 		List		   *ranges,					/* a list of IndexRanges */
 					   *wrappers;				/* a list of WrapperNodes */
@@ -305,6 +307,9 @@ pathman_rel_pathlist_hook(PlannerInfo *root,
 		/* Make copy of partitioning expression and fix Var's  varno attributes */
 		part_expr = PrelExpressionForRelid(prel, rti);
 
+		/* Get partitioning-related clauses (do this before append_child_relation()) */
+		part_clauses = get_partitioning_clauses(rel->baserestrictinfo, prel, rti);
+
 		if (prel->parttype == PT_RANGE)
 		{
 			/*
@@ -382,19 +387,25 @@ pathman_rel_pathlist_hook(PlannerInfo *root,
 		/* Parent has already been locked by rewriter */
 		parent_rel = heap_open(rte->relid, NoLock);
 
-		/* Add parent if asked to */
-		if (prel->enable_parent)
-			append_child_relation(root, parent_rel, rti, 0, rte->relid, NULL);
+		parent_rowmark = get_plan_rowmark(root->rowMarks, rti);
 
 		/*
-		 * Iterate all indexes in rangeset and append corresponding child relations.
+		 * WARNING: 'prel' might become invalid after append_child_relation().
 		 */
+
+		/* Add parent if asked to */
+		if (prel->enable_parent)
+			append_child_relation(root, parent_rel, parent_rowmark,
+								  rti, 0, rte->relid, NULL);
+
+		/* Iterate all indexes in rangeset and append child relations */
 		foreach(lc, ranges)
 		{
 			IndexRange irange = lfirst_irange(lc);
 
 			for (i = irange_lower(irange); i <= irange_upper(irange); i++)
-				append_child_relation(root, parent_rel, rti, i, children[i], wrappers);
+				append_child_relation(root, parent_rel, parent_rowmark,
+									  rti, i, children[i], wrappers);
 		}
 
 		/* Now close parent relation */
@@ -424,9 +435,6 @@ pathman_rel_pathlist_hook(PlannerInfo *root,
 			  pg_pathman_enable_runtime_merge_append))
 			return;
 
-		/* Get partitioning-related clauses */
-		part_clauses = get_partitioning_clauses(rel->baserestrictinfo, prel, rti);
-
 		/* Skip if there's no PARAMs in partitioning-related clauses */
 		if (!clause_contains_params((Node *) part_clauses))
 			return;

src/include/pathman.h

@@ -105,8 +105,12 @@ Oid get_pathman_config_params_relid(bool invalid_is_ok);
 /*
  * Create RelOptInfo & RTE for a selected partition.
  */
-Index append_child_relation(PlannerInfo *root, Relation parent_relation,
-							Index parent_rti, int ir_index, Oid child_oid,
+Index append_child_relation(PlannerInfo *root,
+							Relation parent_relation,
+							PlanRowMark *parent_rowmark,
+							Index parent_rti,
+							int ir_index,
+							Oid child_oid,
 							List *wrappers);
 
 

src/pg_pathman.c

@@ -30,8 +30,9 @@
 #include "optimizer/restrictinfo.h"
 #include "optimizer/cost.h"
 #include "utils/datum.h"
-#include "utils/lsyscache.h"
 #include "utils/rel.h"
+#include "utils/lsyscache.h"
+#include "utils/syscache.h"
 #include "utils/selfuncs.h"
 #include "utils/typcache.h"
 
@@ -364,8 +365,12 @@ get_pathman_config_params_relid(bool invalid_is_ok)
  * NOTE: partially based on the expand_inherited_rtentry() function.
  */
 Index
-append_child_relation(PlannerInfo *root, Relation parent_relation,
-					  Index parent_rti, int ir_index, Oid child_oid,
+append_child_relation(PlannerInfo *root,
+					  Relation parent_relation,
+					  PlanRowMark *parent_rowmark,
+					  Index parent_rti,
+					  int ir_index,
+					  Oid child_oid,
 					  List *wrappers)
 {
 	RangeTblEntry  *parent_rte,
@@ -375,17 +380,35 @@ append_child_relation(PlannerInfo *root, Relation parent_relation,
 	Relation		child_relation;
 	AppendRelInfo  *appinfo;
 	Index			childRTindex;
-	PlanRowMark	   *parent_rowmark,
-				   *child_rowmark;
+	PlanRowMark	   *child_rowmark;
 	Node		   *childqual;
 	List		   *childquals;
 	ListCell	   *lc1,
 				   *lc2;
+	LOCKMODE		lockmode;
+
+	/* Choose a correct lock mode */
+	if (parent_rti == root->parse->resultRelation)
+		lockmode = RowExclusiveLock;
+	else if (parent_rowmark && RowMarkRequiresRowShareLock(parent_rowmark->markType))
+		lockmode = RowShareLock;
+	else
+		lockmode = AccessShareLock;
+
+	/* Acquire a suitable lock on partition */
+	LockRelationOid(child_oid, lockmode);
+
+	/* Check that partition exists */
+	if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(child_oid)))
+	{
+		UnlockRelationOid(child_oid, lockmode);
+		return 0;
+	}
 
 	parent_rel = root->simple_rel_array[parent_rti];
 	parent_rte = root->simple_rte_array[parent_rti];
 
-	/* FIXME: acquire a suitable lock on partition */
+	/* Open child relation (we've just locked it) */
 	child_relation = heap_open(child_oid, NoLock);
 
 	/* Create RangeTblEntry for child relation */
@@ -408,7 +431,6 @@ append_child_relation(PlannerInfo *root, Relation parent_relation,
 
 
 	/* Create rowmarks required for child rels */
-	parent_rowmark = get_plan_rowmark(root->rowMarks, parent_rti);
 	if (parent_rowmark)
 	{
 		child_rowmark = makeNode(PlanRowMark);