[AQUMV] Refactor view query target list process.

Before this commit, we separate view query's targetlist
into pure_vars and no_pure_vars. This is used to match
sub expression for Greedy Algorithm with special order.

However, we could combine all that expression into one list
expcet those have no vars.
The more complex expression is, the higher order is.
And pure vars is guaranteed to be later in order.

Fix some fields lost of TargetEntry by the way.

Authored-by: Zhang Mingli avamingli@gmail.com

Author: avamingli

src/backend/optimizer/plan/aqumv.c

@@ -58,16 +58,15 @@ static Node *aqumv_adjust_varno_mutator(Node *node, aqumv_adjust_varno_context *
 
 typedef struct
 {
-	List	*mv_pure_vars_index; 		/* Index list of pure Vars. */
-	List	*mv_nonpure_vars_index; 	/* Index list of nonpure Vars. */
 	List	*mv_query_tlist;			/* view query's target list. */
+	List	*mv_tlist_ordered_index; 	/* Index list by complexity order. */
 	TupleDesc mv_tupledesc;				/* mv relation's tuple desc. */
 	bool has_unmatched;		/* True if we fail to rewrite an expression. */
 } aqumv_equivalent_transformation_context;
 
 static aqumv_equivalent_transformation_context* aqumv_init_context(List *view_tlist, TupleDesc mv_tupledesc);
 static bool aqumv_process_targetlist(aqumv_equivalent_transformation_context *context, List *query_tlist, List **mv_final_tlist);
-static void aqumv_process_nonpure_vars_expr(aqumv_equivalent_transformation_context* context);
+static void aqumv_sort_targetlist(aqumv_equivalent_transformation_context* context);
 static Node *aqumv_adjust_sub_matched_expr_mutator(Node *node, aqumv_equivalent_transformation_context *context);
 
 typedef struct
@@ -290,9 +289,6 @@ answer_query_using_materialized_views(PlannerInfo *root,
 
 		context = aqumv_init_context(viewQuery->targetList, matviewRel->rd_att);
 
-		/* Sort nonpure vars expression, prepare for Greedy Algorithm. */
-		aqumv_process_nonpure_vars_expr(context);
-
 		/*
 		 * Process and rewrite target list, return false if failed.
 		 */
@@ -444,8 +440,6 @@ static aqumv_equivalent_transformation_context*
 aqumv_init_context(List *view_tlist, TupleDesc mv_tupledesc)
 {
 	aqumv_equivalent_transformation_context *context = palloc0(sizeof(aqumv_equivalent_transformation_context));
-	List	*mv_pure_vars_index = NIL; /* Index of TargetEntry[Var] in view query. */
-	List	*mv_nonpure_vars_index = NIL; /* Index of nonpure[Var] expression in view query. */
 	ListCell *lc;
 
 	/*
@@ -465,17 +459,16 @@ aqumv_init_context(List *view_tlist, TupleDesc mv_tupledesc)
 		if(!contain_var_clause((Node*)tle))
 			continue;
 
-		if (IsA(tle->expr, Var))
-			mv_pure_vars_index = lappend_int(mv_pure_vars_index, i);
-		else
-			mv_nonpure_vars_index = lappend_int(mv_nonpure_vars_index, i);
+		/* To be sorted later */
+		context->mv_tlist_ordered_index = lappend_int(context->mv_tlist_ordered_index, i);
 	}
 
-	context->mv_pure_vars_index = mv_pure_vars_index;
-	context->mv_nonpure_vars_index = mv_nonpure_vars_index;
 	context->mv_tupledesc = mv_tupledesc;
 	context->mv_query_tlist = view_tlist;
 	context->has_unmatched = false;
+
+	/* Sort target list expressions, prepare for Greedy Algorithm. */
+	aqumv_sort_targetlist(context);
 	return context;
 }
 
@@ -503,14 +496,14 @@ nonpure_vars_expr_compare(const ListCell *a, const ListCell *b)
 }
 
 /*
- * In-place update order of mv_nonpure_vars_index List
+ * In-place update order of mv_tlist_ordered_index List
  */
 static void
-aqumv_process_nonpure_vars_expr(aqumv_equivalent_transformation_context* context)
+aqumv_sort_targetlist(aqumv_equivalent_transformation_context* context)
 {
 	ListCell* lc;
 	List	*expr_to_sort_list = NIL;
-	foreach(lc, context->mv_nonpure_vars_index)
+	foreach(lc, context->mv_tlist_ordered_index)
 	{
 		int index = lfirst_int(lc);
 		Node *expr = lfirst(list_nth_cell(context->mv_query_tlist, index));
@@ -524,13 +517,14 @@ aqumv_process_nonpure_vars_expr(aqumv_equivalent_transformation_context* context
 
 	/* Sort the expr list */
 	list_sort(expr_to_sort_list, nonpure_vars_expr_compare);
-	/* Reorder mv_nonpure_vars_index */
-	context->mv_nonpure_vars_index = NIL;
+	/* Reorder */
+	context->mv_tlist_ordered_index = NIL;
 	foreach(lc, expr_to_sort_list)
 	{
 		expr_to_sort *ets = (expr_to_sort *) lfirst(lc);
-		context->mv_nonpure_vars_index = lappend_int(context->mv_nonpure_vars_index, ets->tlist_index);
+		context->mv_tlist_ordered_index = lappend_int(context->mv_tlist_ordered_index, ets->tlist_index);
 	}
+	list_free_deep(expr_to_sort_list);
 	return;
 }
 
@@ -606,7 +600,7 @@ static Node *aqumv_adjust_sub_matched_expr_mutator(Node *node, aqumv_equivalent_
 		return is_targetEntry ? node : (Node *)node_expr;
 
 	ListCell 	*lc = NULL;
-	foreach(lc, context->mv_nonpure_vars_index)
+	foreach(lc, context->mv_tlist_ordered_index)
 	{
 		int index = lfirst_int(lc);
 		TargetEntry *tle = list_nth_node(TargetEntry, context->mv_query_tlist, index);
@@ -618,17 +612,12 @@ static Node *aqumv_adjust_sub_matched_expr_mutator(Node *node, aqumv_equivalent_
 								attr->atttypid,
 								attr->atttypmod,
 								attr->attcollation,
-								0 /* AQUMV_FIXME_MVP: no subquery. */);
-			newVar->location = -2; /* hack here, use -2 to indicate already rewrited by mv rel Vars. */
+								0 /* AQUMV_FIXME_MVP: consider subquery? */);
+			newVar->location = -1;
 			if (is_targetEntry)
 			{
-				TargetEntry *qtle = (TargetEntry *) node;
-				/*
-				 * AQUMV_FIXME_MVP:
-				 * resorigtbl, resorigcol, resjunck in viewQuery is also rejunck in mv table itself ?
-				 */
-				TargetEntry *mvtle = makeTargetEntry((Expr *)newVar, qtle->resno, qtle->resname, qtle->resjunk);
-				return (Node *) mvtle;
+				((TargetEntry *) node)->expr = (Expr*) newVar;
+				return node;
 			}
 			else
 				return (Node *) newVar;
@@ -642,39 +631,14 @@ static Node *aqumv_adjust_sub_matched_expr_mutator(Node *node, aqumv_equivalent_
 	 */
 	if (!contain_var_clause((Node *)node_expr))
 		return is_targetEntry ? node : (Node *)node_expr;
-	
-	/* Try match with mv_pure_vars_index, but do not disturb already rewrited exprs(Var->location = -2)  */
-	if (IsA(node_expr, Var))
-	{
-		Var *var = (Var *)node_expr;
-		if (var->location == -2)
-			return node;
 
-		lc = NULL;
-		foreach(lc, context->mv_pure_vars_index)
-		{
-			int index = lfirst_int(lc);
-			TargetEntry *tle = list_nth_node(TargetEntry, context->mv_query_tlist, index);
-			if (equal(node_expr, tle->expr))
-			{
-				Form_pg_attribute attr = TupleDescAttr(context->mv_tupledesc, index);
-				Var *newVar =  makeVar(1, /* AQUMV_FIXME_MVP: single relation */
-								attr->attnum,
-								attr->atttypid,
-								attr->atttypmod,
-								attr->attcollation,
-								0 /* AQUMV_FIXME_MVP: no subquery. */);
-				if (is_targetEntry)
-				{
-					((TargetEntry *)node)->expr = (Expr *)newVar;
-					return node;
-				}
-				else
-					return (Node *)newVar;
-			}
-		}
+	/*
+	 * Failed to rewrite.
+	 * We have walked through all exprs in mv_tlist_ordered_index,
+	 * but didn't find a match for Var at leaf nodes.
+	 */
+	if (IsA(node_expr, Var))
 		context->has_unmatched = true;
-	}
 
 	return expression_tree_mutator(node, aqumv_adjust_sub_matched_expr_mutator, context);
 }