MDEV-34278: Implements DISTINCT for ST_Collect

Implements the DISTINCT modifier for ST_Collect

Author: StefanoPetrilli <stefanop_1999@hotmail.it>

mysql-test/main/spatial_utility_function_collect.result

@@ -18,6 +18,13 @@ ST_EQUALS( (SELECT ST_COLLECT( location ) AS t FROM
 table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,0 0,1 0,2
 0,3 0) ',4326))
 1
+SELECT ST_EQUALS( (SELECT ST_COLLECT( DISTINCT location ) AS t FROM
+table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,1 0,2 0,3
+0) ',4326));
+ST_EQUALS( (SELECT ST_COLLECT( DISTINCT location ) AS t FROM
+table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,1 0,2 0,3
+0) ',4326))
+1
 INSERT INTO table_simple_aggregation (location) VALUES
 ( ST_GEOMFROMTEXT('POINT(0 -0)'         ,4326)),
 ( NULL);

mysql-test/main/spatial_utility_function_collect.test

@@ -35,9 +35,9 @@ table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,0 0,1 0,2
 0,3 0) ',4326));
 # --echo # Functional requirement F-8 Shall support DISTINCT in aggregates
 # --echo # result shall be 1
-# SELECT ST_EQUALS( (SELECT ST_COLLECT( DISTINCT location ) AS t FROM
-# table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,1 0,2 0,3
-# 0) ',4326));
+SELECT ST_EQUALS( (SELECT ST_COLLECT( DISTINCT location ) AS t FROM
+table_simple_aggregation) , ST_GEOMFROMTEXT('MULTIPOINT(0 0,1 0,2 0,3
+0) ',4326));
 # --echo # Functional requirement F-5: ST_COLLECT shall support group by, which
 # --echo # is given by aggregation machinery
 # --echo # result shall be

sql/item_sum.cc

@@ -4649,6 +4649,9 @@ bool Item_func_collect::add() {
   if (tmp_arg[0]->null_value)
     return 0;
 
+  if(is_distinct && list_contains_element(wkb))
+    return 0;
+
   current_geometry_srid= uint4korr(wkb->ptr());
   if (geometries.is_empty())
     srid= current_geometry_srid;
@@ -4664,7 +4667,6 @@ bool Item_func_collect::add() {
 
 
 void Item_func_collect::remove() {
-  String value;
   String *wkb= args[0]->val_str(&value);
   has_cached_result= false;
 
@@ -4689,17 +4691,34 @@ void Item_func_collect::remove() {
 }
 
 
-Item_func_collect::Item_func_collect(THD *thd, Item *item_par) :
+bool Item_func_collect::list_contains_element(String *wkb) {
+  List_iterator<String> geometries_iterator(geometries);
+  String* temp_geometry;
+  while ((temp_geometry= geometries_iterator++))
+  {
+    String temp(temp_geometry->ptr(), temp_geometry->length(), &my_charset_bin);
+
+    if (wkb->eq(&temp, &my_charset_bin))
+      return true;
+  }
+
+  return false;
+}
+
+
+Item_func_collect::Item_func_collect(THD *thd, bool is_distinct, Item *item_par) :
   Item_sum_int(thd, item_par),
   mem_root(thd->mem_root),
+  is_distinct(is_distinct),
   group_collect_max_len(thd->variables.group_concat_max_len)
 {
 }
 
 
-Item_func_collect::Item_func_collect(THD *thd, Item_func_collect *item) :
+Item_func_collect::Item_func_collect(THD *thd, bool is_distinct, Item_func_collect *item) :
   Item_sum_int(thd, item),
   mem_root(thd->mem_root),
+  is_distinct(is_distinct),
   group_collect_max_len(thd->variables.group_concat_max_len)
 {
 }
@@ -4776,5 +4795,5 @@ String *Item_func_collect::val_str(String *str)
 
 
 Item *Item_func_collect::copy_or_same(THD *thd) {
-  return new (thd->mem_root) Item_func_collect(thd, this);
+  return new (thd->mem_root) Item_func_collect(thd, is_distinct, this);
 }

sql/item_sum.h

@@ -2129,6 +2129,7 @@ class Item_func_collect :public Item_sum_int
   bool has_cached_result;
   String cached_result;
   MEM_ROOT *mem_root;
+  bool is_distinct;
   List<String> geometries;
   String value;
   const uint group_collect_max_len;
@@ -2137,10 +2138,11 @@ class Item_func_collect :public Item_sum_int
   bool add() override;
   void cleanup() override;
   void remove() override;
+  bool list_contains_element(String* wkb);
 
 public:
-  Item_func_collect(THD *thd, Item *item_par);
-  Item_func_collect(THD *thd, Item_func_collect *item);
+  Item_func_collect(THD *thd, bool is_distinct, Item *item_par);
+  Item_func_collect(THD *thd, bool is_distinct, Item_func_collect *item);
 
   enum Sumfunctype sum_func () const override
   {

sql/sql_yacc.yy

@@ -11033,9 +11033,9 @@ sum_expr:
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | ST_COLLECT_SYM '(' in_sum_expr ')'
+        | ST_COLLECT_SYM '(' opt_distinct in_sum_expr ')'
           {
-            $$= new (thd->mem_root) Item_func_collect(thd, $3);
+            $$= new (thd->mem_root) Item_func_collect(thd, $3, $4);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }