Add test for ordered projections

Author: knizhnik

expected/test.out

@@ -333,3 +333,68 @@ select count(*) from vit where i>='1 minute'::interval;
      2
 (1 row)
 
+create table stock(symbol char(5), day date, low real, high real, open real, close real);
+insert into stock values
+('AAA', '01-11-2018', 10.0, 11.0, 10.1, 10.8),
+('AAA', '02-11-2018', 11.0, 12.0, 11.2, 11.5),
+('AAA', '03-11-2018', 10.4, 10.6, 10.5, 10.4),
+('AAA', '04-11-2018', 11.1, 11.5, 11.2, 11.4),
+('AAA', '05-11-2018', 11.0, 11.3, 11.4, 11.1);
+select create_projection('vstock','stock',array['day','low','high','open','close'],array['symbol'],'day');
+ create_projection 
+-------------------
+ 
+(1 row)
+
+select vstock_refresh();
+ vstock_refresh 
+----------------
+              5
+(1 row)
+
+select avg((open+close)/2),max(high-low) from stock group by symbol;
+       avg       | max 
+-----------------+-----
+ 10.960000038147 |   1
+(1 row)
+
+set vops.auto_substitute_projections=on;
+explain (costs off) select avg((open+close)/2),max(high-low) from stock group by symbol;
+        QUERY PLAN        
+--------------------------
+ HashAggregate
+   Group Key: symbol
+   ->  Seq Scan on vstock
+(3 rows)
+
+select avg((open+close)/2),max(high-low) from stock group by symbol;
+       avg       | max 
+-----------------+-----
+ 10.960000038147 |   1
+(1 row)
+
+insert into stock values
+('AAA', '06-11-2018', 10.1, 10.8, 10.3, 10.2),
+('AAA', '07-11-2018', 11.1, 11.8, 10.2, 11.4),
+('AAA', '08-11-2018', 11.2, 11.6, 11.4, 11.3),
+('AAA', '09-11-2018', 10.6, 11.1, 11.3, 10.8),
+('AAA', '10-11-2018', 10.7, 11.3, 10.8, 11.1);
+select vstock_refresh();
+ vstock_refresh 
+----------------
+              5
+(1 row)
+
+select avg((open+close)/2),max(high-low) from stock group by symbol;
+       avg        | max 
+------------------+-----
+ 10.9200000762939 |   1
+(1 row)
+
+set vops.auto_substitute_projections=off;
+select avg((open+close)/2),max(high-low) from stock group by symbol;
+       avg        | max 
+------------------+-----
+ 10.9200000762939 |   1
+(1 row)
+

sql/test.sql

@@ -42,10 +42,10 @@ insert into stock values
 select create_projection('vstock','stock',array['day','low','high','open','close'],array['symbol'],'day');
 
 select vstock_refresh();
-select avg((open+close)/2),max(high-low) from stock group by day;
+select avg((open+close)/2),max(high-low) from stock group by symbol;
 set vops.auto_substitute_projections=on;
-explain (costs off) select avg((open+close)/2),max(high-low) from stock group by day;
-select avg((open+close)/2),max(high-low) from stock group by day;
+explain (costs off) select avg((open+close)/2),max(high-low) from stock group by symbol;
+select avg((open+close)/2),max(high-low) from stock group by symbol;
 
 insert into stock values
 ('AAA', '06-11-2018', 10.1, 10.8, 10.3, 10.2),
@@ -55,6 +55,6 @@ insert into stock values
 ('AAA', '10-11-2018', 10.7, 11.3, 10.8, 11.1);
 select vstock_refresh();
 
-select avg((open+close)/2),max(high-low) from stock group by day;
+select avg((open+close)/2),max(high-low) from stock group by symbol;
 set vops.auto_substitute_projections=off;
-select avg((open+close)/2),max(high-low) from stock group by day;
+select avg((open+close)/2),max(high-low) from stock group by symbol;

vops.c

@@ -3446,6 +3446,9 @@ vops_add_index_cond(Node* clause, List* conjuncts, char const* keyName)
 static Node*
 vops_add_literal_type_casts(Node* node, Const** consts)
 {
+	if (node == NULL)
+		return NULL;
+
 	if (IsA(node, BoolExpr))
 	{
 		ListCell* cell;
@@ -3679,9 +3682,11 @@ static void vops_explain_hook(Query *query,
 		list_length(query->rtable) == 1  && /* do not support substitution for joins because it is not clear how to handle case when only of of joined table is substituted with parition */
 		params == NULL)    /* do not support prepared statements yet */
 	{
-		char* select = pstrdup(queryString);
-		memset(select, ' ', 7);  /* clear "explain" prefix */
-		vops_substitute_tables_with_projections(select, query);
+		char* explain = pstrdup(queryString);
+		char* select = strstr(explain, "select");
+		size_t prefix = (select != NULL) ? (select - explain) : 7;
+		memset(explain, ' ', prefix);  /* clear "explain" prefix */
+		vops_substitute_tables_with_projections(explain, query);
 	}
 	(void)query_tree_mutator(query, vops_expression_tree_mutator, &ctx, QTW_DONT_COPY_QUERY);