A fix and a test case for Bug#6513 "Test Suite: Values inserted by using

cursor is interpreted latin1 character and Bug#9819 "Cursors: Mysql Server
Crash while fetching from table with 5 million records."
A fix for a possible memory leak when fetching into an SP cursor
in a long loop.
The patch uses a common implementation of cursors in the binary protocol and 
in stored procedures and implements materialized cursors.
For implementation details, see comments in sql_cursor.cc

include/my_sys.h

@@ -775,6 +775,7 @@ extern void my_free_lock(byte *ptr,myf flags);
 extern void init_alloc_root(MEM_ROOT *mem_root, uint block_size,
 			    uint pre_alloc_size);
 extern gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size);
+extern gptr multi_alloc_root(MEM_ROOT *mem_root, ...);
 extern void free_root(MEM_ROOT *root, myf MyFLAGS);
 extern void set_prealloc_root(MEM_ROOT *root, char *ptr);
 extern void reset_root_defaults(MEM_ROOT *mem_root, uint block_size,

libmysqld/Makefile.am

@@ -60,7 +60,7 @@ sqlsources = derror.cc field.cc field_conv.cc strfunc.cc filesort.cc \
 	sql_string.cc sql_table.cc sql_test.cc sql_udf.cc \
 	sql_update.cc sql_yacc.cc table.cc thr_malloc.cc time.cc \
 	unireg.cc uniques.cc stacktrace.c sql_union.cc hash_filo.cc \
-	spatial.cc gstream.cc sql_help.cc tztime.cc protocol_cursor.cc \
+	spatial.cc gstream.cc sql_help.cc tztime.cc sql_cursor.cc \
 	sp_head.cc sp_pcontext.cc sp.cc sp_cache.cc sp_rcontext.cc \
 	parse_file.cc sql_view.cc sql_trigger.cc my_decimal.cc \
 	ha_blackhole.cc

mysql-test/r/ctype_ujis.result

@@ -2271,3 +2271,33 @@ select c1 from t1 where c1 like 'abcde111%' order by c1;
 c1
 abcde111
 drop table t1;
+DROP TABLE IF EXISTS t1, t2;
+DROP PROCEDURE IF EXISTS sp1;
+set names ujis;
+set character_set_database = ujis;
+set character_set_server = ujis;
+CREATE TABLE t1(c1 char(2)) default charset = ujis;
+CREATE TABLE t2(c2 char(2)) default charset = ujis;
+INSERT INTO t1 VALUES(_ujis 0xA4A2);
+CREATE PROCEDURE sp1()
+BEGIN
+DECLARE a CHAR(1);
+DECLARE cur1 CURSOR FOR SELECT c1 FROM t1;
+OPEN cur1;
+FETCH cur1 INTO a;
+INSERT INTO t2 VALUES (a);
+CLOSE cur1;
+END|
+CALL sp1();
+SELECT c1,c2 FROM t1,t2;
+c1	c2
+あ	あ
+SELECT hex(convert(_latin1 0xA4A2 using ujis)),hex(c2) FROM t1,t2;
+hex(convert(_latin1 0xA4A2 using ujis))	hex(c2)
+8FA2F0A1F1	A4A2
+DROP PROCEDURE sp1;
+DROP TABLE t1;
+DROP TABLE t2;
+set names default;
+set character_set_database=default;
+set character_set_server=default;

mysql-test/r/sp-big.result

@@ -13,3 +13,49 @@ select @value;
 3
 drop procedure test.longprocedure;
 drop table t1;
+create table t1 (f1 char(100) , f2 mediumint , f3 int , f4 real, f5 numeric);
+insert into t1 (f1, f2, f3, f4, f5) values
+("This is a test case for for Bug#9819", 1, 2, 3.0, 4.598);
+Warnings:
+Note	1265	Data truncated for column 'f5' at row 1
+create table t2 like t1;
+select count(*) from t1;
+count(*)
+256
+select count(*) from t2;
+count(*)
+0
+create procedure p1()
+begin
+declare done integer default 0;
+declare vf1 char(100) ;
+declare vf2 mediumint;
+declare vf3 int ;
+declare vf4 real ;
+declare vf5 numeric ;
+declare cur1 cursor for select f1,f2,f3,f4,f5 from t1;  
+declare continue handler for sqlstate '02000' set done = 1; 
+open cur1;
+while done <> 1 do
+fetch cur1 into vf1, vf2, vf3, vf4, vf5;
+if not done then
+insert into t2 values (vf1, vf2, vf3, vf4, vf5);
+end if;
+end while;
+close cur1;
+end|
+call p1();
+select count(*) from t1;
+count(*)
+256
+select count(*) from t2;
+count(*)
+256
+select f1 from t1 limit 1;
+f1
+This is a test case for for Bug#9819
+select f1 from t2 limit 1;
+f1
+This is a test case for for Bug#9819
+drop procedure p1;
+drop table t1, t2;

mysql-test/t/ctype_ujis.test

@@ -1151,3 +1151,45 @@ SET collation_connection='ujis_bin';
 -- source include/ctype_innodb_like.inc
 
 # End of 4.1 tests
+--disable_warnings
+DROP TABLE IF EXISTS t1, t2;
+DROP PROCEDURE IF EXISTS sp1;
+--enable_warnings
+
+set names ujis;
+set character_set_database = ujis;
+set character_set_server = ujis;
+
+CREATE TABLE t1(c1 char(2)) default charset = ujis;
+CREATE TABLE t2(c2 char(2)) default charset = ujis;
+
+INSERT INTO t1 VALUES(_ujis 0xA4A2);
+
+DELIMITER |;
+CREATE PROCEDURE sp1()
+BEGIN
+  DECLARE a CHAR(1);
+  DECLARE cur1 CURSOR FOR SELECT c1 FROM t1;
+  OPEN cur1;
+  FETCH cur1 INTO a;
+  INSERT INTO t2 VALUES (a);
+  CLOSE cur1;
+END|
+DELIMITER ;|
+CALL sp1();
+
+#The data in t1 and t2 should be the same but different
+SELECT c1,c2 FROM t1,t2;
+
+#Since the result of hex(convert(_latin1 0xA4A2 using ujis))
+#equals to hex(c2), it seems that the value which was inserted 
+#by using cursor is interpreted as latin1 character set
+SELECT hex(convert(_latin1 0xA4A2 using ujis)),hex(c2) FROM t1,t2;
+
+DROP PROCEDURE sp1;
+DROP TABLE t1;
+DROP TABLE t2;
+
+set names default;
+set character_set_database=default;
+set character_set_server=default;

mysql-test/t/sp-big.test

@@ -31,3 +31,52 @@ call test.longprocedure(@value); select @value;
 
 drop procedure test.longprocedure;
 drop table t1;
+#
+# Bug #9819 "Cursors: Mysql Server Crash while fetching from table with 5
+# million records.": 
+# To really test the bug, increase the number of loop iterations ($1).
+# For 4 millions set $1 to 22.
+create table t1 (f1 char(100) , f2 mediumint , f3 int , f4 real, f5 numeric);
+insert into t1 (f1, f2, f3, f4, f5) values
+("This is a test case for for Bug#9819", 1, 2, 3.0, 4.598);
+create table t2 like t1;
+let $1=8;
+--disable_query_log
+--disable_result_log
+while ($1)
+{
+  eval insert into t1 select * from t1;
+  dec $1;
+}
+--enable_result_log
+--enable_query_log
+select count(*) from t1;
+select count(*) from t2;
+delimiter |;
+create procedure p1()
+begin
+  declare done integer default 0;
+  declare vf1 char(100) ;
+  declare vf2 mediumint;
+  declare vf3 int ;
+  declare vf4 real ;
+  declare vf5 numeric ;
+  declare cur1 cursor for select f1,f2,f3,f4,f5 from t1;  
+  declare continue handler for sqlstate '02000' set done = 1; 
+  open cur1;
+  while done <> 1 do
+    fetch cur1 into vf1, vf2, vf3, vf4, vf5;
+    if not done then
+      insert into t2 values (vf1, vf2, vf3, vf4, vf5);
+    end if;
+  end while;
+  close cur1;
+end|
+delimiter ;|
+call p1();
+select count(*) from t1;
+select count(*) from t2;
+select f1 from t1 limit 1;
+select f1 from t2 limit 1;
+drop procedure p1;
+drop table t1, t2;

mysys/my_alloc.c

@@ -221,6 +221,57 @@ gptr alloc_root(MEM_ROOT *mem_root,unsigned int Size)
 #endif
 }
 
+
+/*
+  Allocate many pointers at the same time.
+
+  DESCRIPTION
+    ptr1, ptr2, etc all point into big allocated memory area.
+
+  SYNOPSIS
+    multi_alloc_root()
+      root               Memory root
+      ptr1, length1      Multiple arguments terminated by a NULL pointer
+      ptr2, length2      ...
+      ...
+      NULL
+
+  RETURN VALUE
+    A pointer to the beginning of the allocated memory block
+    in case of success or NULL if out of memory.
+*/
+
+gptr multi_alloc_root(MEM_ROOT *root, ...)
+{
+  va_list args;
+  char **ptr, *start, *res;
+  uint tot_length, length;
+  DBUG_ENTER("multi_alloc_root");
+
+  va_start(args, root);
+  tot_length= 0;
+  while ((ptr= va_arg(args, char **)))
+  {
+    length= va_arg(args, uint);
+    tot_length+= ALIGN_SIZE(length);
+  }
+  va_end(args);
+
+  if (!(start= (char*) alloc_root(root, tot_length)))
+    DBUG_RETURN(0);                            /* purecov: inspected */
+
+  va_start(args, root);
+  res= start;
+  while ((ptr= va_arg(args, char **)))
+  {
+    *ptr= res;
+    length= va_arg(args, uint);
+    res+= ALIGN_SIZE(length);
+  }
+  va_end(args);
+  DBUG_RETURN((gptr) start);
+}
+
 #define TRASH_MEM(X) TRASH(((char*)(X) + ((X)->size-(X)->left)), (X)->left)
 
 /* Mark all data in blocks free for reusage */

sql/Makefile.am

@@ -61,7 +61,7 @@ noinst_HEADERS =	item.h item_func.h item_sum.h item_cmpfunc.h \
                         tztime.h my_decimal.h\
 			sp_head.h sp_pcontext.h sp_rcontext.h sp.h sp_cache.h \
 			parse_file.h sql_view.h	sql_trigger.h \
-			sql_array.h \
+			sql_array.h sql_cursor.h \
 			examples/ha_example.h examples/ha_archive.h \
 			examples/ha_tina.h ha_blackhole.h  \
 			ha_federated.h
@@ -94,7 +94,7 @@ mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			client.c sql_client.cc mini_client_errors.c pack.c\
 			stacktrace.c repl_failsafe.h repl_failsafe.cc \
 			sql_olap.cc sql_view.cc \
-			gstream.cc spatial.cc sql_help.cc protocol_cursor.cc \
+			gstream.cc spatial.cc sql_help.cc sql_cursor.cc \
                         tztime.cc my_time.c my_decimal.cc\
 			sp_head.cc sp_pcontext.cc  sp_rcontext.cc sp.cc \
 			sp_cache.cc parse_file.cc sql_trigger.cc \

sql/handler.cc

@@ -1339,11 +1339,9 @@ int handler::ha_open(const char *name, int mode, int test_if_locked)
       table->db_stat|=HA_READ_ONLY;
     (void) extra(HA_EXTRA_NO_READCHECK);	// Not needed in SQL
 
-    if (!alloc_root_inited(&table->mem_root))	// If temporary table
-      ref=(byte*) sql_alloc(ALIGN_SIZE(ref_length)*2);
-    else
-      ref=(byte*) alloc_root(&table->mem_root, ALIGN_SIZE(ref_length)*2);
-    if (!ref)
+    DBUG_ASSERT(alloc_root_inited(&table->mem_root));
+
+    if (!(ref= (byte*) alloc_root(&table->mem_root, ALIGN_SIZE(ref_length)*2)))
     {
       close();
       error=HA_ERR_OUT_OF_MEM;

sql/item_subselect.cc

@@ -1468,7 +1468,7 @@ int subselect_single_select_engine::prepare()
 
 int subselect_union_engine::prepare()
 {
-  return unit->prepare(thd, result, SELECT_NO_UNLOCK, "");
+  return unit->prepare(thd, result, SELECT_NO_UNLOCK);
 }
 
 int subselect_uniquesubquery_engine::prepare()

sql/protocol.h

@@ -150,30 +150,6 @@ class Protocol_prep :public Protocol
   virtual bool store(Field *field);
 };
 
-class Protocol_cursor :public Protocol_simple
-{
-public:
-  MEM_ROOT *alloc;
-  MYSQL_FIELD *fields;
-  MYSQL_ROWS *data;
-  MYSQL_ROWS **prev_record;
-  ulong row_count;
-
-  Protocol_cursor() :data(NULL) {}
-  Protocol_cursor(THD *thd_arg, MEM_ROOT *ini_alloc) :Protocol_simple(thd_arg), alloc(ini_alloc), data(NULL) {}
-  bool prepare_for_send(List<Item> *item_list) 
-  {
-    row_count= 0;
-    fields= NULL;
-    data= NULL;
-    prev_record= &data;
-    return Protocol_simple::prepare_for_send(item_list);
-  }
-  bool send_fields(List<Item> *list, uint flags);
-  bool write();
-  uint get_field_count() { return field_count; }
-};
-
 void send_warning(THD *thd, uint sql_errno, const char *err=0);
 void net_printf_error(THD *thd, uint sql_errno, ...);
 void net_send_error(THD *thd, uint sql_errno=0, const char *err=0);

sql/sp_head.cc

@@ -199,11 +199,18 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
   Item *it= sp_prepare_func_item(thd, it_addr);
   uint rsize;
   Query_arena backup_arena;
+  Item *old_item_next, *old_free_list, **p_free_list;
   DBUG_PRINT("info", ("type: %d", type));
 
   if (!it)
-  {
     DBUG_RETURN(NULL);
+
+  if (reuse)
+  {
+    old_item_next= reuse->next;
+    p_free_list= use_callers_arena ? &thd->spcont->callers_arena->free_list :
+                                     &thd->free_list;
+    old_free_list= *p_free_list;
   }
 
   switch (sp_map_result_type(type)) {
@@ -312,15 +319,23 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
   default:
     DBUG_ASSERT(0);
   }
-  it->rsize= rsize;
-
-  DBUG_RETURN(it);
+  goto end;
 
 return_null_item:
   CREATE_ON_CALLERS_ARENA(it= new(reuse, &rsize) Item_null(),
                     use_callers_arena, &backup_arena);
+end:
   it->rsize= rsize;
 
+  if (reuse && it == reuse)
+  {
+    /*
+      The Item constructor registered itself in the arena free list,
+      while the item slot is reused, so we have to restore the list.
+    */
+    it->next= old_item_next;
+    *p_free_list= old_free_list;
+  }
   DBUG_RETURN(it);
 }
 
@@ -1358,14 +1373,6 @@ int sp_head::execute_procedure(THD *thd, List<Item> *args)
 	  uint offset= static_cast<Item_splocal *>(it)->get_offset();
 	  Item *val= nctx->get_item(i);
 	  Item *orig= octx->get_item(offset);
-	  Item *o_item_next;
-          /* we'll use callers_arena in sp_eval_func_item */
-	  Item *o_free_list= thd->spcont->callers_arena->free_list;
-
-	  LINT_INIT(o_item_next);
-
-	  if (orig)
-	    o_item_next= orig->next;
 
           /*
             We might need to allocate new item if we weren't able to
@@ -1380,15 +1387,6 @@ int sp_head::execute_procedure(THD *thd, List<Item> *args)
 	  }
 	  if (copy != orig)
 	    octx->set_item(offset, copy);
-	  if (orig && copy == orig)
-	  {
-	    /*
-              A reused item slot, where the constructor put it in the
-              free_list, so we have to restore the list.
-            */
-	    thd->spcont->callers_arena->free_list= o_free_list;
-	    copy->next= o_item_next;
-	  }
 	}
 	else
 	{
@@ -2476,6 +2474,10 @@ sp_instr_cpop::backpatch(uint dest, sp_pcontext *dst_ctx)
 int
 sp_instr_copen::execute(THD *thd, uint *nextp)
 {
+  /*
+    We don't store a pointer to the cursor in the instruction to be
+    able to reuse the same instruction among different threads in future.
+  */
   sp_cursor *c= thd->spcont->get_cursor(m_cursor);
   int res;
   DBUG_ENTER("sp_instr_copen::execute");
@@ -2484,41 +2486,33 @@ sp_instr_copen::execute(THD *thd, uint *nextp)
     res= -1;
   else
   {
-    sp_lex_keeper *lex_keeper= c->pre_open(thd);
-    if (!lex_keeper)                            // cursor already open or OOM
-    {
-      res= -1;
-      *nextp= m_ip+1;
-    }
-    else
-    {
-      Query_arena *old_arena= thd->stmt_arena;
+    sp_lex_keeper *lex_keeper= c->get_lex_keeper();
+    Query_arena *old_arena= thd->stmt_arena;
 
-      /*
-        Get the Query_arena from the cpush instruction, which contains
-        the free_list of the query, so new items (if any) are stored in
-        the right free_list, and we can cleanup after each open.
-      */
-      thd->stmt_arena= c->get_instr();
-      res= lex_keeper->reset_lex_and_exec_core(thd, nextp, FALSE, this);
-      /* Cleanup the query's items */
-      if (thd->stmt_arena->free_list)
-        cleanup_items(thd->stmt_arena->free_list);
-      thd->stmt_arena= old_arena;
-      /*
-        Work around the fact that errors in selects are not returned properly
-        (but instead converted into a warning), so if a condition handler
-        caught, we have lost the result code.
-      */
-      if (!res)
-      {
-        uint dummy1, dummy2;
+    /*
+      Get the Query_arena from the cpush instruction, which contains
+      the free_list of the query, so new items (if any) are stored in
+      the right free_list, and we can cleanup after each open.
+    */
+    thd->stmt_arena= c->get_instr();
+    res= lex_keeper->reset_lex_and_exec_core(thd, nextp, FALSE, this);
+    /* Cleanup the query's items */
+    if (thd->stmt_arena->free_list)
+      cleanup_items(thd->stmt_arena->free_list);
+    thd->stmt_arena= old_arena;
+    /*
+      Work around the fact that errors in selects are not returned properly
+      (but instead converted into a warning), so if a condition handler
+      caught, we have lost the result code.
+    */
+    if (!res)
+    {
+      uint dummy1, dummy2;
 
-        if (thd->spcont->found_handler(&dummy1, &dummy2))
-  	  res= -1;
-      }
-      c->post_open(thd, res ? FALSE : TRUE);
+      if (thd->spcont->found_handler(&dummy1, &dummy2))
+        res= -1;
     }
+    /* TODO: Assert here that we either have an error or a cursor */
   }
   DBUG_RETURN(res);
 }
@@ -2527,7 +2521,8 @@ sp_instr_copen::execute(THD *thd, uint *nextp)
 int
 sp_instr_copen::exec_core(THD *thd, uint *nextp)
 {
-  int res= mysql_execute_command(thd);
+  sp_cursor *c= thd->spcont->get_cursor(m_cursor);
+  int res= c->open(thd);
   *nextp= m_ip+1;
   return res;
 }
@@ -2582,14 +2577,7 @@ sp_instr_cfetch::execute(THD *thd, uint *nextp)
   Query_arena backup_arena;
   DBUG_ENTER("sp_instr_cfetch::execute");
 
-  if (! c)
-    res= -1;
-  else
-  {
-    thd->set_n_backup_active_arena(thd->spcont->callers_arena, &backup_arena);
-    res= c->fetch(thd, &m_varlist);
-    thd->restore_active_arena(thd->spcont->callers_arena, &backup_arena);
-  }
+  res= c ? c->fetch(thd, &m_varlist) : -1;
 
   *nextp= m_ip+1;
   DBUG_RETURN(res);

sql/sp_head.h

@@ -860,6 +860,12 @@ class sp_instr_cpush : public sp_instr
 
   virtual void print(String *str);
 
+  /*
+    This call is used to cleanup the instruction when a sensitive
+    cursor is closed. For now stored procedures always use materialized
+    cursors and the call is not used.
+  */
+  virtual void cleanup_stmt() { /* no op */ }
 private:
 
   sp_lex_keeper m_lex_keeper;
@@ -1041,4 +1047,7 @@ sp_add_to_query_tables(THD *thd, LEX *lex,
 		       const char *db, const char *name,
 		       thr_lock_type locktype);
 
+Item *sp_eval_func_item(THD *thd, Item **it, enum_field_types type,
+                        Item *reuse, bool use_callers_arena);
+
 #endif /* _SP_HEAD_H_ */

sql/sp_rcontext.cc

@@ -25,6 +25,7 @@
 
 #include "mysql.h"
 #include "sp_head.h"
+#include "sql_cursor.h"
 #include "sp_rcontext.h"
 #include "sp_pcontext.h"
 
@@ -45,31 +46,18 @@ int
 sp_rcontext::set_item_eval(THD *thd, uint idx, Item **item_addr,
 			   enum_field_types type)
 {
-  extern Item *sp_eval_func_item(THD *thd, Item **it, enum_field_types type,
-				 Item *reuse, bool use_callers_arena);
   Item *it;
   Item *reuse_it;
-  Item *old_item_next;
   /* sp_eval_func_item will use callers_arena */
-  Item *old_free_list= thd->spcont->callers_arena->free_list;
   int res;
-  LINT_INIT(old_item_next);
 
-  if ((reuse_it= get_item(idx)))
-    old_item_next= reuse_it->next;
+  reuse_it= get_item(idx);
   it= sp_eval_func_item(thd, item_addr, type, reuse_it, TRUE);
   if (! it)
     res= -1;
   else
   {
     res= 0;
-    if (reuse_it && it == reuse_it)
-    {
-      // A reused item slot, where the constructor put it in the free_list,
-      // so we have to restore the list.
-      thd->spcont->callers_arena->free_list= old_free_list;
-      it->next= old_item_next;
-    }
     set_item(idx, it);
   }
 
@@ -170,7 +158,8 @@ sp_rcontext::pop_cursors(uint count)
  */
 
 sp_cursor::sp_cursor(sp_lex_keeper *lex_keeper, sp_instr_cpush *i)
-  :m_lex_keeper(lex_keeper), m_prot(NULL), m_isopen(0), m_current_row(NULL),
+  :m_lex_keeper(lex_keeper),
+   server_side_cursor(NULL),
    m_i(i)
 {
   /*
@@ -182,59 +171,37 @@ sp_cursor::sp_cursor(sp_lex_keeper *lex_keeper, sp_instr_cpush *i)
 
 
 /*
-  pre_open cursor
+  Open an SP cursor
 
   SYNOPSIS
-    pre_open()
-    THD		Thread handler
+    open()
+    THD		         Thread handler
 
-  NOTES
-    We have to open cursor in two steps to make it easy for sp_instr_copen
-    to reuse the sp_instr::exec_stmt() code.
-    If this function returns 0, post_open should not be called
 
   RETURN
-   0  ERROR
+   0 in case of success, -1 otherwise
 */
 
-sp_lex_keeper*
-sp_cursor::pre_open(THD *thd)
+int
+sp_cursor::open(THD *thd)
 {
-  if (m_isopen)
+  if (server_side_cursor)
   {
     my_message(ER_SP_CURSOR_ALREADY_OPEN, ER(ER_SP_CURSOR_ALREADY_OPEN),
                MYF(0));
-    return NULL;
+    return -1;
   }
-  init_alloc_root(&m_mem_root, MEM_ROOT_BLOCK_SIZE, MEM_ROOT_PREALLOC);
-  if ((m_prot= new Protocol_cursor(thd, &m_mem_root)) == NULL)
-    return NULL;
-
-  /* Save for execution. Will be restored in post_open */
-  m_oprot= thd->protocol;
-  m_nseof= thd->net.no_send_eof;
-
-  /* Change protocol for execution */
-  thd->protocol= m_prot;
-  thd->net.no_send_eof= TRUE;
-  return m_lex_keeper;
-}
-
-
-void
-sp_cursor::post_open(THD *thd, my_bool was_opened)
-{
-  thd->net.no_send_eof= m_nseof; // Restore the originals
-  thd->protocol= m_oprot;
-  if ((m_isopen= was_opened))
-    m_current_row= m_prot->data;
+  if (mysql_open_cursor(thd, (uint) ALWAYS_MATERIALIZED_CURSOR, &result,
+                        &server_side_cursor))
+    return -1;
+  return 0;
 }
 
 
 int
 sp_cursor::close(THD *thd)
 {
-  if (! m_isopen)
+  if (! server_side_cursor)
   {
     my_message(ER_SP_CURSOR_NOT_OPEN, ER(ER_SP_CURSOR_NOT_OPEN), MYF(0));
     return -1;
@@ -247,106 +214,82 @@ sp_cursor::close(THD *thd)
 void
 sp_cursor::destroy()
 {
-  if (m_prot)
-  {
-    delete m_prot;
-    m_prot= NULL;
-    free_root(&m_mem_root, MYF(0));
-  }
-  m_isopen= FALSE;
+  delete server_side_cursor;
+  server_side_cursor= 0;
 }
 
+
 int
 sp_cursor::fetch(THD *thd, List<struct sp_pvar> *vars)
 {
-  List_iterator_fast<struct sp_pvar> li(*vars);
-  sp_pvar_t *pv;
-  MYSQL_ROW row;
-  uint fldcount;
-
-  if (! m_isopen)
+  if (! server_side_cursor)
   {
     my_message(ER_SP_CURSOR_NOT_OPEN, ER(ER_SP_CURSOR_NOT_OPEN), MYF(0));
     return -1;
   }
-  if (m_current_row == NULL)
+  if (vars->elements != result.get_field_count())
   {
-    my_message(ER_SP_FETCH_NO_DATA, ER(ER_SP_FETCH_NO_DATA), MYF(0));
+    my_message(ER_SP_WRONG_NO_OF_FETCH_ARGS,
+               ER(ER_SP_WRONG_NO_OF_FETCH_ARGS), MYF(0));
     return -1;
   }
 
-  row= m_current_row->data;
-  for (fldcount= 0 ; (pv= li++) ; fldcount++)
-  {
-    Item *it;
-    Item *reuse;
-    uint rsize;
-    Item *old_item_next;
-    Item *old_free_list= thd->free_list;
-    const char *s;
-    LINT_INIT(old_item_next);
-
-    if (fldcount >= m_prot->get_field_count())
-    {
-      my_message(ER_SP_WRONG_NO_OF_FETCH_ARGS,
-                 ER(ER_SP_WRONG_NO_OF_FETCH_ARGS), MYF(0));
-      return -1;
-    }
+  result.set_spvar_list(vars);
 
-    if ((reuse= thd->spcont->get_item(pv->offset)))
-      old_item_next= reuse->next;
+  /* Attempt to fetch one row */
+  if (server_side_cursor->is_open())
+    server_side_cursor->fetch(1);
 
-    s= row[fldcount];
-    if (!s)
-      it= new(reuse, &rsize) Item_null();
-    else
-    {
-      /*
-        Length of data can be calculated as:
-        pointer_to_next_not_null_object - s -1
-        where the last -1 is to remove the end \0
-      */
-      uint len;
-      MYSQL_ROW next= row+fldcount+1;
-      while (!*next)                             // Skip nulls
-        next++;
-      len= (*next -s)-1;
-      switch (sp_map_result_type(pv->type)) {
-      case INT_RESULT:
-	it= new(reuse, &rsize) Item_int(s);
-	break;
-      case REAL_RESULT:
-        it= new(reuse, &rsize) Item_float(s, len);
-	break;
-      case DECIMAL_RESULT:
-        it= new(reuse, &rsize) Item_decimal(s, len, thd->db_charset);
-        break;
-      case STRING_RESULT:
-        /* TODO: Document why we do an extra copy of the string 's' here */
-        it= new(reuse, &rsize) Item_string(thd->strmake(s, len), len,
-					   thd->db_charset);
-        break;
-      case ROW_RESULT:
-      default:
-        DBUG_ASSERT(0);
-      }
-    }
-    it->rsize= rsize;
-    if (reuse && it == reuse)
-    {
-      // A reused item slot, where the constructor put it in the free_list,
-      // so we have to restore the list.
-      thd->free_list= old_free_list;
-      it->next= old_item_next;
-    }
-    thd->spcont->set_item(pv->offset, it);
-  }
-  if (fldcount < m_prot->get_field_count())
+  /*
+    If the cursor was pointing after the last row, the fetch will
+    close it instead of sending any rows.
+  */
+  if (! server_side_cursor->is_open())
   {
-    my_message(ER_SP_WRONG_NO_OF_FETCH_ARGS,
-               ER(ER_SP_WRONG_NO_OF_FETCH_ARGS), MYF(0));
+    my_message(ER_SP_FETCH_NO_DATA, ER(ER_SP_FETCH_NO_DATA), MYF(0));
     return -1;
   }
-  m_current_row= m_current_row->next;
+
   return 0;
 }
+
+
+/***************************************************************************
+ Select_fetch_into_spvars
+****************************************************************************/
+
+int Select_fetch_into_spvars::prepare(List<Item> &fields, SELECT_LEX_UNIT *u)
+{
+  /*
+    Cache the number of columns in the result set in order to easily
+    return an error if column count does not match value count.
+  */
+  field_count= fields.elements;
+  return select_result_interceptor::prepare(fields, u);
+}
+
+
+bool Select_fetch_into_spvars::send_data(List<Item> &items)
+{
+  List_iterator_fast<struct sp_pvar> pv_iter(*spvar_list);
+  List_iterator_fast<Item> item_iter(items);
+  sp_pvar_t *pv;
+  Item *item;
+
+  /* Must be ensured by the caller */
+  DBUG_ASSERT(spvar_list->elements == items.elements);
+
+  /*
+    Assign the row fetched from a server side cursor to stored
+    procedure variables.
+  */
+  for (; pv= pv_iter++, item= item_iter++; )
+  {
+    Item *reuse= thd->spcont->get_item(pv->offset);
+    /* Evaluate a new item on the arena of the calling instruction */
+    Item *it= sp_eval_func_item(thd, &item, pv->type, reuse, TRUE);
+
+    thd->spcont->set_item(pv->offset, it);
+  }
+  return FALSE;
+}

sql/sp_rcontext.h

@@ -216,6 +216,27 @@ class sp_rcontext : public Sql_alloc
 }; // class sp_rcontext : public Sql_alloc
 
 
+/*
+  An interceptor of cursor result set used to implement
+  FETCH <cname> INTO <varlist>.
+*/
+
+class Select_fetch_into_spvars: public select_result_interceptor
+{
+  List<struct sp_pvar> *spvar_list;
+  uint field_count;
+public:
+  uint get_field_count() { return field_count; }
+  void set_spvar_list(List<struct sp_pvar> *vars) { spvar_list= vars; }
+
+  virtual bool send_eof() { return FALSE; }
+  virtual bool send_data(List<Item> &items);
+  virtual int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
+};
+
+
+/* A mediator between stored procedures and server side cursors */
+
 class sp_cursor : public Sql_alloc
 {
 public:
@@ -227,12 +248,11 @@ class sp_cursor : public Sql_alloc
     destroy();
   }
 
-  // We have split this in two to make it easy for sp_instr_copen
-  // to reuse the sp_instr::exec_stmt() code.
   sp_lex_keeper *
-  pre_open(THD *thd);
-  void
-  post_open(THD *thd, my_bool was_opened);
+  get_lex_keeper() { return m_lex_keeper; }
+
+  int
+  open(THD *thd);
 
   int
   close(THD *thd);
@@ -240,7 +260,7 @@ class sp_cursor : public Sql_alloc
   inline my_bool
   is_open()
   {
-    return m_isopen;
+    return test(server_side_cursor);
   }
 
   int
@@ -251,18 +271,13 @@ class sp_cursor : public Sql_alloc
   {
     return m_i;
   }
-  
+
 private:
 
-  MEM_ROOT m_mem_root;		// My own mem_root
+  Select_fetch_into_spvars result;
   sp_lex_keeper *m_lex_keeper;
-  Protocol_cursor *m_prot;
-  my_bool m_isopen;
-  my_bool m_nseof;		// Original no_send_eof
-  Protocol *m_oprot;		// Original protcol
-  MYSQL_ROWS *m_current_row;
+  Server_side_cursor *server_side_cursor;
   sp_instr_cpush *m_i;		// My push instruction
-  
   void
   destroy();
 

sql/sql_class.cc

@@ -1544,6 +1544,19 @@ void Query_arena::free_items()
 }
 
 
+void Query_arena::set_query_arena(Query_arena *set)
+{
+  mem_root=  set->mem_root;
+  free_list= set->free_list;
+  state= set->state;
+}
+
+
+void Query_arena::cleanup_stmt()
+{
+  DBUG_ASSERT("Query_arena::cleanup_stmt()" == "not implemented");
+}
+
 /*
   Statement functions 
 */
@@ -1601,12 +1614,6 @@ void Statement::restore_backup_statement(Statement *stmt, Statement *backup)
 }
 
 
-void Statement::close_cursor()
-{
-  DBUG_ASSERT("Statement::close_cursor()" == "not implemented");
-}
-
-
 void THD::end_statement()
 {
   /* Cleanup SQL processing state to resuse this statement in next query. */
@@ -1648,13 +1655,6 @@ void THD::restore_active_arena(Query_arena *set, Query_arena *backup)
   DBUG_VOID_RETURN;
 }
 
-void Query_arena::set_query_arena(Query_arena *set)
-{
-  mem_root=  set->mem_root;
-  free_list= set->free_list;
-  state= set->state;
-}
-
 Statement::~Statement()
 {
   /*
@@ -1723,9 +1723,11 @@ int Statement_map::insert(Statement *statement)
 
 void Statement_map::close_transient_cursors()
 {
+#ifdef TO_BE_IMPLEMENTED
   Statement *stmt;
   while ((stmt= transient_cursor_list.head()))
     stmt->close_cursor();                 /* deletes itself from the list */
+#endif
 }
 
 

sql/sql_class.h

@@ -737,10 +737,12 @@ class Query_arena
   void set_query_arena(Query_arena *set);
 
   void free_items();
+  /* Close the active state associated with execution of this statement */
+  virtual void cleanup_stmt();
 };
 
 
-class Cursor;
+class Server_side_cursor;
 
 /*
   State of a single command executed against this connection.
@@ -816,7 +818,7 @@ class Statement: public ilink, public Query_arena
   */
   char *query;
   uint32 query_length;                          // current query length
-  Cursor *cursor;
+  Server_side_cursor *cursor;
 
 public:
 
@@ -833,8 +835,6 @@ class Statement: public ilink, public Query_arena
   void restore_backup_statement(Statement *stmt, Statement *backup);
   /* return class type */
   virtual Type type() const;
-  /* Close the cursor open for this statement, if there is one */
-  virtual void close_cursor();
 };
 
 
@@ -886,9 +886,6 @@ class Statement_map
     }
     hash_delete(&st_hash, (byte *) statement);
   }
-  void add_transient_cursor(Statement *stmt)
-  { transient_cursor_list.append(stmt); }
-  void erase_transient_cursor(Statement *stmt) { stmt->unlink(); }
   /*
     Close all cursors of this connection that use tables of a storage
     engine that has transaction-specific state and therefore can not
@@ -1812,18 +1809,21 @@ class TMP_TABLE_PARAM :public Sql_alloc
   }
 };
 
-class select_union :public select_result_interceptor {
- public:
-  TABLE *table;
+class select_union :public select_result_interceptor
+{
   TMP_TABLE_PARAM tmp_table_param;
+public:
+  TABLE *table;
 
-  select_union(TABLE *table_par);
-  ~select_union();
+  select_union() :table(0) {}
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &items);
   bool send_eof();
   bool flush();
-  void set_table(TABLE *tbl) { table= tbl; }
+
+  bool create_result_table(THD *thd, List<Item> *column_types,
+                           bool is_distinct, ulonglong options,
+                           const char *alias);
 };
 
 /* Base subselect interface class */

sql/sql_cursor.h

+#ifndef _sql_cursor_h_
+#define _sql_cursor_h_
+/* Copyright (C) 2005 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+#ifdef USE_PRAGMA_INTERFACE
+#pragma interface                              /* gcc class interface */
+#endif
+
+/*
+  Declarations for implementation of server side cursors. Only
+  read-only non-scrollable cursors are currently implemented.
+*/
+
+/*
+  Server_side_cursor -- an interface for materialized and
+  sensitive (non-materialized) implementation of cursors. All
+  cursors are self-contained (created in their own memory root).
+  For that reason they must be deleted only using a pointer to
+  Server_side_cursor, not to its base class.
+*/
+
+class Server_side_cursor: protected Query_arena, public Sql_alloc
+{
+protected:
+  /* Row destination used for fetch */
+  select_result *result;
+public:
+  Server_side_cursor(MEM_ROOT *mem_root_arg, select_result *result_arg)
+    :Query_arena(mem_root_arg, INITIALIZED), result(result_arg)
+  {}
+
+  virtual bool is_open() const= 0;
+
+  virtual int open(JOIN *top_level_join)= 0;
+  virtual void fetch(ulong num_rows)= 0;
+  virtual void close()= 0;
+  virtual ~Server_side_cursor();
+
+  static void operator delete(void *ptr, size_t size);
+};
+
+
+int mysql_open_cursor(THD *thd, uint flags,
+                      select_result *result,
+                      Server_side_cursor **res);
+
+/* Possible values for flags */
+
+enum { ANY_CURSOR= 1, ALWAYS_MATERIALIZED_CURSOR= 2 };
+
+#endif /* _sql_cusor_h_ */

sql/sql_derived.cc

@@ -27,7 +27,7 @@
 
 
 /*
-  call given derived table processor (preparing or filling tables)
+  Call given derived table processor (preparing or filling tables)
 
   SYNOPSIS
     mysql_handle_derived()
@@ -36,7 +36,6 @@
 
   RETURN
     0	ok
-    -1	Error
     1	Error and error message given
 */
 
@@ -97,14 +96,14 @@ mysql_handle_derived(LEX *lex, int (*processor)(THD*, LEX*, TABLE_LIST*))
 
   RETURN
     0	ok
-    1	Error
-    -1	Error and error message given
-  */
+    1	Error and an error message was given
+*/
 
 int mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
 {
   SELECT_LEX_UNIT *unit= orig_table_list->derived;
   int res= 0;
+  ulonglong create_options;
   DBUG_ENTER("mysql_derived_prepare");
   if (unit)
   {
@@ -118,21 +117,18 @@ int mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
     for (SELECT_LEX *sl= first_select; sl; sl= sl->next_select())
       sl->context.outer_context= 0;
 
-    if (!(derived_result= new select_union(0)))
+    if (!(derived_result= new select_union))
       DBUG_RETURN(1); // out of memory
 
     // st_select_lex_unit::prepare correctly work for single select
-    if ((res= unit->prepare(thd, derived_result, 0, orig_table_list->alias)))
+    if ((res= unit->prepare(thd, derived_result, 0)))
       goto exit;
 
-    if (check_duplicate_names(unit->types, 0))
-    {
-      res= -1;
+    if ((res= check_duplicate_names(unit->types, 0)))
       goto exit;
-    }
 
-    derived_result->tmp_table_param.init();
-    derived_result->tmp_table_param.field_count= unit->types.elements;
+    create_options= (first_select->options | thd->options |
+                     TMP_TABLE_ALL_COLUMNS);
     /*
       Temp table is created so that it hounours if UNION without ALL is to be 
       processed
@@ -143,18 +139,12 @@ int mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
       !unit->union_distinct->next_select() (i.e. it is union and last distinct
       SELECT is last SELECT of UNION).
     */
-    if (!(table= create_tmp_table(thd, &derived_result->tmp_table_param,
-				  unit->types, (ORDER*) 0,
-				  FALSE, 1,
-				  (first_select->options | thd->options |
-				   TMP_TABLE_ALL_COLUMNS),
-				  HA_POS_ERROR,
-				  orig_table_list->alias)))
-    {
-      res= -1;
+    if ((res= derived_result->create_result_table(thd, &unit->types, FALSE,
+                                                 create_options,
+                                                 orig_table_list->alias)))
       goto exit;
-    }
-    derived_result->set_table(table);
+
+    table= derived_result->table;
 
 exit:
     /* Hide "Unknown column" or "Unknown function" error */
@@ -231,9 +221,8 @@ int mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
 
   RETURN
     0	ok
-    1	Error
-    -1	Error and error message given
-  */
+    1   Error and an error message was given
+*/
 
 int mysql_derived_filling(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
 {

sql/sql_lex.h

@@ -432,10 +432,6 @@ class st_select_lex_unit: public st_select_lex_node {
   {
     return my_reinterpret_cast(st_select_lex*)(slave);
   }
-  st_select_lex* first_select_in_union() 
-  { 
-    return my_reinterpret_cast(st_select_lex*)(slave);
-  }
   st_select_lex_unit* next_unit()
   {
     return my_reinterpret_cast(st_select_lex_unit*)(next);
@@ -445,8 +441,7 @@ class st_select_lex_unit: public st_select_lex_node {
   void exclude_tree();
 
   /* UNION methods */
-  bool prepare(THD *thd, select_result *result, ulong additional_options,
-               const char *tmp_table_alias);
+  bool prepare(THD *thd, select_result *result, ulong additional_options);
   bool exec();
   bool cleanup();
   inline void unclean() { cleaned= 0; }
@@ -462,7 +457,10 @@ class st_select_lex_unit: public st_select_lex_node {
 
   friend void lex_start(THD *thd, uchar *buf, uint length);
   friend int subselect_union_engine::exec();
+
+  List<Item> *get_unit_column_types();
 };
+
 typedef class st_select_lex_unit SELECT_LEX_UNIT;
 
 /*

sql/sql_list.h

@@ -32,6 +32,8 @@ class Sql_alloc
   {
     return (void*) sql_alloc((uint) size);
   }
+  static void *operator new[](size_t size, MEM_ROOT *mem_root)
+  { return (void*) alloc_root(mem_root, (uint) size); }
   static void *operator new(size_t size, MEM_ROOT *mem_root)
   { return (void*) alloc_root(mem_root, (uint) size); }
   static void operator delete(void *ptr, size_t size) { TRASH(ptr, size); }

sql/sql_select.h

@@ -101,7 +101,7 @@ enum enum_nested_loop_state
 typedef enum_nested_loop_state
 (*Next_select_func)(JOIN *, struct st_join_table *, bool);
 typedef int (*Read_record_func)(struct st_join_table *tab);
-
+Next_select_func setup_end_select_func(JOIN *join);
 
 typedef struct st_join_table {
   TABLE		*table;
@@ -140,6 +140,11 @@ typedef struct st_join_table {
   void cleanup();
 } JOIN_TAB;
 
+enum_nested_loop_state sub_select_cache(JOIN *join, JOIN_TAB *join_tab, bool
+                                        end_of_records);
+enum_nested_loop_state sub_select(JOIN *join,JOIN_TAB *join_tab, bool
+                                  end_of_records);
+
 
 typedef struct st_position			/* Used in find_best */
 {
@@ -372,58 +377,6 @@ class JOIN :public Sql_alloc
 };
 
 
-/*
-  Server-side cursor (now stands only for basic read-only cursor)
-  See class implementation in sql_select.cc
-  A cursor has its own runtime state - list of used items and memory root of
-  used memory - which is different from Prepared statement runtime: it must
-  be different at least for the purpose of reusing the same prepared
-  statement for many cursors.
-*/
-
-class Cursor: public Sql_alloc, public Query_arena
-{
-  MEM_ROOT main_mem_root;
-  JOIN *join;
-  SELECT_LEX_UNIT *unit;
-
-  TABLE *open_tables;
-  MYSQL_LOCK *lock;
-  TABLE *derived_tables;
-  /* List of items created during execution */
-  query_id_t query_id;
-  struct Engine_info
-  {
-    const handlerton *ht;
-    void *read_view;
-  };
-  Engine_info ht_info[MAX_HA];
-public:
-  Protocol_prep protocol;
-  Item_change_list change_list;
-  select_send result;
-  THR_LOCK_OWNER lock_id;
-  my_bool close_at_commit;
-
-  /* Temporary implementation as now we replace THD state by value */
-  /* Save THD state into cursor */
-  void init_from_thd(THD *thd);
-  /* bzero cursor state in THD */
-  void reset_thd(THD *thd);
-
-  int open(JOIN *join);
-  void fetch(ulong num_rows);
-  void reset() { join= 0; }
-  bool is_open() const { return join != 0; }
-
-  void close(bool is_active);
-
-  void set_unit(SELECT_LEX_UNIT *unit_arg) { unit= unit_arg; }
-  Cursor(THD *thd);
-  ~Cursor() {}
-};
-
-
 typedef struct st_select_check {
   uint const_ref,reg_ref;
 } SELECT_CHECK;

sql/sql_view.cc

@@ -378,7 +378,7 @@ bool mysql_create_view(THD *thd,
 
   /* prepare select to resolve all fields */
   lex->view_prepare_mode= 1;
-  if (unit->prepare(thd, 0, 0, view->view_name.str))
+  if (unit->prepare(thd, 0, 0))
   {
     /*
       some errors from prepare are reported to user, if is not then

sql/table.cc

@@ -1687,6 +1687,63 @@ db_type get_table_type(THD *thd, const char *name)
   DBUG_RETURN(ha_checktype(thd,(enum db_type) (uint) *(head+3),0,0));
 }
 
+/*
+  Create Item_field for each column in the table.
+
+  SYNPOSIS
+    st_table::fill_item_list()
+      item_list          a pointer to an empty list used to store items
+
+  DESCRIPTION
+    Create Item_field object for each column in the table and
+    initialize it with the corresponding Field. New items are
+    created in the current THD memory root.
+
+  RETURN VALUE
+    0                    success
+    1                    out of memory
+*/
+
+bool st_table::fill_item_list(List<Item> *item_list) const
+{
+  /*
+    All Item_field's created using a direct pointer to a field
+    are fixed in Item_field constructor.
+  */
+  for (Field **ptr= field; *ptr; ptr++)
+  {
+    Item_field *item= new Item_field(*ptr);
+    if (!item || item_list->push_back(item))
+      return TRUE;
+  }
+  return FALSE;
+}
+
+/*
+  Reset an existing list of Item_field items to point to the
+  Fields of this table.
+
+  SYNPOSIS
+    st_table::fill_item_list()
+      item_list          a non-empty list with Item_fields
+
+  DESCRIPTION
+    This is a counterpart of fill_item_list used to redirect
+    Item_fields to the fields of a newly created table.
+    The caller must ensure that number of items in the item_list
+    is the same as the number of columns in the table.
+*/
+
+void st_table::reset_item_list(List<Item> *item_list) const
+{
+  List_iterator_fast<Item> it(*item_list);
+  for (Field **ptr= field; *ptr; ptr++)
+  {
+    Item_field *item_field= (Item_field*) it++;
+    DBUG_ASSERT(item_field != 0);
+    item_field->reset_field(*ptr);
+  }
+}
 
 /*
   calculate md5 of query

sql/table.h

@@ -267,6 +267,9 @@ struct st_table {
   GRANT_INFO grant;
   FILESORT_INFO sort;
   TABLE_SHARE share_not_to_be_used;     /* To be deleted when true shares */
+
+  bool fill_item_list(List<Item> *item_list) const;
+  void reset_item_list(List<Item> *item_list) const;
 };
 
 

tests/mysql_client_test.c

@@ -13828,8 +13828,11 @@ static void test_bug10760()
   rc= mysql_stmt_execute(stmt);
   check_execute(stmt, rc);
   rc= mysql_query(mysql, "update t1 set id=id+100");
-  DIE_UNLESS(rc);
-  if (!opt_silent)
+  /*
+    If cursors are not materialized, the update will return an error;
+    we mainly test that it won't deadlock.
+  */
+  if (rc && !opt_silent)
     printf("Got error (as expected): %s\n", mysql_error(mysql));
   /*
     2: check that MyISAM tables used in cursors survive