MDEV-11297: Add support for LIMIT clause in GROUP_CONCAT()

mysql-test/r/func_gconcat.result

@@ -1254,3 +1254,129 @@ DROP TABLE t1;
 #
 # End of 10.2 tests
 #
+#
+# Start of 10.3 tests
+#
+drop table if exists t1, t2;
+create table t1 (grp int, a bigint unsigned, c char(10) , d char(10) not null);
+insert into t1 values (1,1,NULL,"a");
+insert into t1 values (1,10,"b","a");
+insert into t1 values (1,11,"c","a");
+insert into t1 values (2,2,"c","a");
+insert into t1 values (2,3,"b","b");
+insert into t1 values (3,4,"E","a");
+insert into t1 values (3,5,"C","b");
+insert into t1 values (3,6,"D","c");
+insert into t1 values (3,7,"E","c");
+select grp,group_concat(c) from t1 group by grp;
+grp	group_concat(c)
+1	b,c
+2	c,b
+3	E,C,D,E
+select grp,group_concat(c limit 1  ) from t1 group by grp;
+grp	group_concat(c limit 1  )
+1	b
+2	c
+3	E
+select grp,group_concat(c limit 1,1 ) from t1 group by grp;
+grp	group_concat(c limit 1,1 )
+1	c
+2	b
+3	C
+select grp,group_concat(c limit 1,10 ) from t1 group by grp;
+grp	group_concat(c limit 1,10 )
+1	c
+2	b
+3	C,D,E
+select grp,group_concat(c limit 1000) from t1 group by grp;
+grp	group_concat(c limit 1000)
+1	b,c
+2	c,b
+3	E,C,D,E
+select group_concat(grp limit 0) from t1;
+group_concat(grp limit 0)
+
+select group_concat(grp limit "sdjadjs") from t1
+--error ER_PARSE_ERROR
+select grp,group_concat(c limit 5.5) from t1 group by grp ;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '"sdjadjs") from t1
+--error ER_PARSE_ERROR
+select grp,group_concat(c limit 5.5) f' at line 1
+select grp,group_concat(distinct c limit 1,10 ) from t1 group by grp;
+grp	group_concat(distinct c limit 1,10 )
+1	c
+2	b
+3	C,D
+select grp,group_concat(c order by a) from t1 group by grp;
+grp	group_concat(c order by a)
+1	b,c
+2	c,b
+3	E,C,D,E
+select grp,group_concat(c order by a limit 2 ) from t1 group by grp;
+grp	group_concat(c order by a limit 2 )
+1	b,c
+2	c,b
+3	E,C
+select grp,group_concat(c order by a limit 1,1 ) from t1 group by grp;
+grp	group_concat(c order by a limit 1,1 )
+1	c
+2	b
+3	C
+select grp,group_concat(c order by c) from t1 group by grp;
+grp	group_concat(c order by c)
+1	b,c
+2	b,c
+3	C,D,E,E
+select grp,group_concat(c order by c limit 2) from t1 group by grp;
+grp	group_concat(c order by c limit 2)
+1	b,c
+2	b,c
+3	C,D
+select grp,group_concat(c order by c desc) from t1 group by grp;
+grp	group_concat(c order by c desc)
+1	c,b
+2	c,b
+3	E,E,D,C
+select grp,group_concat(c order by c desc limit 2) from t1 group by grp;
+grp	group_concat(c order by c desc limit 2)
+1	c,b
+2	c,b
+3	E,E
+drop table t1;
+create table t2 (a int, b varchar(10));
+insert into t2 values(1,'a'),(1,'b'),(NULL,'c'),(2,'x'),(2,'y');
+select group_concat(a,b limit 2) from t2;
+group_concat(a,b limit 2)
+1a,1b
+set @x=4;
+prepare STMT from 'select group_concat(b limit ?) from t2';
+execute STMT using @x;
+group_concat(b limit ?)
+a,b,c,x
+set @x=2;
+execute STMT using @x;
+group_concat(b limit ?)
+a,b
+set @x=1000;
+execute STMT using @x;
+group_concat(b limit ?)
+a,b,c,x,y
+set @x=0;
+execute STMT using @x;
+group_concat(b limit ?)
+
+set @x="adasfa";
+execute STMT using @x;
+ERROR HY000: Limit only accepts integer values
+set @x=-1;
+execute STMT using @x;
+ERROR HY000: Incorrect arguments to EXECUTE
+set @x=4;
+prepare STMT from 'select group_concat(a,b limit ?) from t2';
+execute STMT using @x;
+group_concat(a,b limit ?)
+1a,1b,2x,2y
+drop table t2;
+#
+# End of 10.3 tests
+#

mysql-test/t/func_gconcat.test

@@ -915,3 +915,76 @@ DROP TABLE t1;
 --echo #
 --echo # End of 10.2 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.3 tests
+--echo #
+
+#
+# MDEV-11297: Add support for LIMIT clause in GROUP_CONCAT()
+#
+--disable_warnings
+drop table if exists t1, t2;
+--enable_warnings
+
+create table t1 (grp int, a bigint unsigned, c char(10) , d char(10) not null);
+insert into t1 values (1,1,NULL,"a");
+insert into t1 values (1,10,"b","a");
+insert into t1 values (1,11,"c","a");
+insert into t1 values (2,2,"c","a");
+insert into t1 values (2,3,"b","b");
+insert into t1 values (3,4,"E","a");
+insert into t1 values (3,5,"C","b");
+insert into t1 values (3,6,"D","c");
+insert into t1 values (3,7,"E","c");
+
+
+select grp,group_concat(c) from t1 group by grp;
+select grp,group_concat(c limit 1  ) from t1 group by grp;
+select grp,group_concat(c limit 1,1 ) from t1 group by grp;
+select grp,group_concat(c limit 1,10 ) from t1 group by grp;
+select grp,group_concat(c limit 1000) from t1 group by grp;
+select group_concat(grp limit 0) from t1;
+--error ER_PARSE_ERROR
+select group_concat(grp limit "sdjadjs") from t1
+--error ER_PARSE_ERROR
+select grp,group_concat(c limit 5.5) from t1 group by grp ;
+select grp,group_concat(distinct c limit 1,10 ) from t1 group by grp;
+select grp,group_concat(c order by a) from t1 group by grp;
+select grp,group_concat(c order by a limit 2 ) from t1 group by grp;
+select grp,group_concat(c order by a limit 1,1 ) from t1 group by grp;
+select grp,group_concat(c order by c) from t1 group by grp;
+select grp,group_concat(c order by c limit 2) from t1 group by grp;
+select grp,group_concat(c order by c desc) from t1 group by grp;
+select grp,group_concat(c order by c desc limit 2) from t1 group by grp;
+
+drop table t1;
+
+create table t2 (a int, b varchar(10));
+insert into t2 values(1,'a'),(1,'b'),(NULL,'c'),(2,'x'),(2,'y');
+select group_concat(a,b limit 2) from t2;
+
+set @x=4;
+prepare STMT from 'select group_concat(b limit ?) from t2';
+execute STMT using @x;
+set @x=2;
+execute STMT using @x;
+set @x=1000;
+execute STMT using @x;
+set @x=0;
+execute STMT using @x;
+set @x="adasfa";
+--error ER_INVALID_VALUE_TO_LIMIT
+execute STMT using @x;
+set @x=-1;
+--error ER_WRONG_ARGUMENTS
+execute STMT using @x;
+set @x=4;
+prepare STMT from 'select group_concat(a,b limit ?) from t2';
+execute STMT using @x;
+drop table t2;
+
+--echo #
+--echo # End of 10.3 tests
+--echo #

sql/item_sum.cc

@@ -3533,13 +3533,26 @@ int dump_leaf_key(void* key_arg, element_count count __attribute__((unused)),
   Item **arg= item->args, **arg_end= item->args + item->arg_count_field;
   uint old_length= result->length();
 
+  ulonglong *offset_limit= &item->copy_offset_limit;
+  ulonglong *row_limit = &item->copy_row_limit;
+  if (item->limit_clause && !(*row_limit))
+    return 1;
+
   if (item->no_appended)
     item->no_appended= FALSE;
   else
     result->append(*item->separator);
 
   tmp.length(0);
 
+  if (item->limit_clause && (*offset_limit))
+  {
+    item->row_count++;
+    item->no_appended= TRUE;
+    (*offset_limit)--;
+    return 0;
+  }
+
   for (; arg < arg_end; arg++)
   {
     String *res;
@@ -3569,6 +3582,8 @@ int dump_leaf_key(void* key_arg, element_count count __attribute__((unused)),
       result->append(*res);
   }
 
+  if (item->limit_clause)
+    (*row_limit)--;
   item->row_count++;
 
   /* stop if length of result more than max_length */
@@ -3617,7 +3632,8 @@ Item_func_group_concat::
 Item_func_group_concat(THD *thd, Name_resolution_context *context_arg,
                        bool distinct_arg, List<Item> *select_list,
                        const SQL_I_List<ORDER> &order_list,
-                       String *separator_arg)
+                       String *separator_arg, bool limit_clause,
+                       Item *row_limit_arg, Item *offset_limit_arg)
   :Item_sum(thd), tmp_table_param(0), separator(separator_arg), tree(0),
    unique_filter(NULL), table(0),
    order(0), context(context_arg),
@@ -3626,7 +3642,9 @@ Item_func_group_concat(THD *thd, Name_resolution_context *context_arg,
    row_count(0),
    distinct(distinct_arg),
    warning_for_row(FALSE),
-   force_copy_fields(0), original(0)
+   force_copy_fields(0), row_limit(NULL),
+   offset_limit(NULL), limit_clause(limit_clause),
+   copy_offset_limit(0), copy_row_limit(0), original(0)
 {
   Item *item_select;
   Item **arg_ptr;
@@ -3668,6 +3686,11 @@ Item_func_group_concat(THD *thd, Name_resolution_context *context_arg,
   /* orig_args is only used for print() */
   orig_args= (Item**) (order + arg_count_order);
   memcpy(orig_args, args, sizeof(Item*) * arg_count);
+  if (limit_clause)
+  {
+    row_limit= row_limit_arg;
+    offset_limit= offset_limit_arg;
+  }
 }
 
 
@@ -3687,7 +3710,9 @@ Item_func_group_concat::Item_func_group_concat(THD *thd,
   warning_for_row(item->warning_for_row),
   always_null(item->always_null),
   force_copy_fields(item->force_copy_fields),
-  original(item)
+  row_limit(item->row_limit), offset_limit(item->offset_limit),
+  limit_clause(item->limit_clause),copy_offset_limit(item->copy_offset_limit),
+  copy_row_limit(item->copy_row_limit), original(item)
 {
   quick_group= item->quick_group;
   result.set_charset(collation.collation);
@@ -3782,6 +3807,10 @@ void Item_func_group_concat::clear()
   null_value= TRUE;
   warning_for_row= FALSE;
   no_appended= TRUE;
+  if (offset_limit)
+    copy_offset_limit= offset_limit->val_int();
+  if (row_limit)
+    copy_row_limit= row_limit->val_int();
   if (tree)
     reset_tree(tree);
   if (unique_filter)
@@ -4036,6 +4065,12 @@ bool Item_func_group_concat::setup(THD *thd)
                               (void*)this,
                               tree_key_length,
                               ram_limitation(thd));
+  if ((row_limit && row_limit->cmp_type() != INT_RESULT) ||
+      (offset_limit && offset_limit->cmp_type() != INT_RESULT))
+  {
+    my_error(ER_INVALID_VALUE_TO_LIMIT, MYF(0));
+    DBUG_RETURN(TRUE);
+  }
 
   DBUG_RETURN(FALSE);
 }