From 2c411a5dc3b7bb6a3b8c4c9017814c8fbadd8770 Mon Sep 17 00:00:00 2001
From: Varun Gupta <varunraiko1803@gmail.com>
Date: Tue, 27 Dec 2016 01:53:22 +0530
Subject: MDEV-11297 Add support for LIMIT clause in GROUP_CONCAT

Comments added, parser rules updated
---
 sql/item_sum.cc | 14 +++++--------
 sql/item_sum.h  |  4 ++++
 sql/sql_yacc.yy | 64 ++++++++-------------------------------------------------
 3 files changed, 17 insertions(+), 65 deletions(-)

diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index 6b3e5252b44..126ab9d84f6 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -3218,7 +3218,7 @@ 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, bool limit_clause,
-                       Item *rowLimit, Item *offsetLimit)
+                       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),
@@ -3227,8 +3227,8 @@ 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),row_limit(0),
-   offset_limit(0),limit_clause(limit_clause),
+   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;
@@ -3274,12 +3274,8 @@ Item_func_group_concat(THD *thd, Name_resolution_context *context_arg,
 
   if (limit_clause)
   {
-    if (!(row_limit=(Item*) thd->alloc(sizeof(Item))))
-      return;
-    row_limit= rowLimit;
-    if (!(offset_limit= (Item*)thd->alloc(sizeof(Item))))
-      return;
-    offset_limit= offsetLimit;
+    row_limit= row_limit_arg;
+    offset_limit= offset_limit_arg;
   }
 }
 
diff --git a/sql/item_sum.h b/sql/item_sum.h
index 49cb9ee72da..d7822a03719 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -1583,10 +1583,14 @@ class Item_func_group_concat : public Item_sum
   bool always_null;
   bool force_copy_fields;
   bool no_appended;
+  /** Limits the rows in the result */
   Item *row_limit;
+  /** Skips a particular number of rows in from the result*/
   Item *offset_limit;
   bool limit_clause;
+  /* copy of the offset limit */
   ulonglong copy_offset_limit;
+  /*copy of the row limit */
   ulonglong copy_row_limit;
 
   /*
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 445058dcc43..f4f64e57ff3 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -1844,7 +1844,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
         opt_escape
         sp_opt_default
         simple_ident_nospvar simple_ident_q
-        field_or_var limit_option glimit_option
+        field_or_var limit_option
         part_func_expr
         window_func_expr
         window_func
@@ -10708,25 +10708,28 @@ glimit_clause_init:
         ;
 
 glimit_clause:
-          glimit_clause_init glimit_options{}
+          glimit_clause_init glimit_options
+          {
+            Lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_LIMIT);
+          }
         ;
 
 glimit_options:
-          glimit_option
+          limit_option
           {
             SELECT_LEX *sel= Select;
             sel->select_limit= $1;
             sel->offset_limit= 0;
             sel->explicit_limit= 1;
           }
-        | glimit_option ',' glimit_option
+        | limit_option ',' limit_option
           {
             SELECT_LEX *sel= Select;
             sel->select_limit= $3;
             sel->offset_limit= $1;
             sel->explicit_limit= 1;
           }
-        | glimit_option OFFSET_SYM glimit_option
+        | limit_option OFFSET_SYM limit_option
           {
             SELECT_LEX *sel= Select;
             sel->select_limit= $1;
@@ -10735,57 +10738,6 @@ glimit_options:
           }
         ;
 
-glimit_option:
-        ident
-        {
-          Item_splocal *splocal;
-          LEX *lex= thd->lex;
-          Lex_input_stream *lip= & thd->m_parser_state->m_lip;
-          sp_variable *spv;
-          sp_pcontext *spc = lex->spcont;
-          if (spc && (spv = spc->find_variable($1, false)))
-          {
-            splocal= new (thd->mem_root)
-              Item_splocal(thd, $1, spv->offset, spv->sql_type(),
-                  lip->get_tok_start() - lex->sphead->m_tmp_query,
-                  lip->get_ptr() - lip->get_tok_start());
-            if (splocal == NULL)
-              MYSQL_YYABORT;
-#ifndef DBUG_OFF
-            splocal->m_sp= lex->sphead;
-#endif
-            lex->safe_to_cache_query=0;
-          }
-          else
-            my_yyabort_error((ER_SP_UNDECLARED_VAR, MYF(0), $1.str));
-          if (splocal->type() != Item::INT_ITEM)
-            my_yyabort_error((ER_WRONG_SPVAR_TYPE_IN_LIMIT, MYF(0)));
-          splocal->limit_clause_param= TRUE;
-          $$= splocal;
-        }
-        | param_marker
-        {
-          $1->limit_clause_param= TRUE;
-        }
-        | ULONGLONG_NUM
-          {
-            $$= new (thd->mem_root) Item_uint(thd, $1.str, $1.length);
-            if ($$ == NULL)
-              MYSQL_YYABORT;
-          }
-        | LONG_NUM
-          {
-            $$= new (thd->mem_root) Item_uint(thd, $1.str, $1.length);
-            if ($$ == NULL)
-              MYSQL_YYABORT;
-          }
-        | NUM
-          {
-            $$= new (thd->mem_root) Item_uint(thd, $1.str, $1.length);
-            if ($$ == NULL)
-              MYSQL_YYABORT;
-          }
-        ;
 
 in_sum_expr:
           opt_all
-- 
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