Backport of revid 2617.69.21, 2617.69.22, 2617.29.23:

----------------------------------------------------------
revno: 2617.69.21
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-4284-1-assert
timestamp: Thu 2009-08-13 20:13:55 +0400
message:
  A fix and a test case for Bug#46610 "MySQL 5.4.4: MyISAM MRG engine crash
  on auto-repair of child".
  Also fixes Bug#42862 "Crash on failed attempt to open a children of a
  merge table".

  MERGE engine needs to extend the global table list
  with TABLE_LIST elements for child tables,
  so that they are opened and locked.
  Previously these table list elements were allocated
  in memory of ha_myisammrg object (MERGE engine handler).
  That would lead to access to freed memory in
  recover_from_failed_open_table_attempt(), which would
  try to recover a MERGE table child (MyISAM table)
  and use for that TABLE_LIST of that child.
  But by the time recover_from_failed_open_table_attempt()
  is invoked, ha_myisammrg object that owns this
  TABLE_LIST may be destroyed, and thus TABLE_LIST
  memory freed.

  The fix is to ensure that TABLE_LIST elements
  that are added to the global table list (lex->query_tables)
  are always allocated in thd->mem_root, which is not
  destroyed until end of execution.

  If previously TABLE_LIST elements were allocated
  at ha_myisammrg::open() (i.e. when the TABLE
  object was created and added to the table cache),
  now they are allocated in ha_myisammrg::add_chidlren_list()
  (i.e. right after "open" of the merge parent in
  open_tables()).
  We still create a list of children names
  at ha_myisammrg::open() to use as a basis
  for creation of TABLE_LISTs, that allows
  to avoid reading the merge handler data
  file on every execution.


mysql-test/r/merge_recover.result:
  Test results for Bug#46610.
mysql-test/t/merge_recover-master.opt:
  Option file for Bug#46610 test (need a new test because
  of that option, which is not tested anywhere else).
mysql-test/t/merge_recover.test:
  Add a test case for Bug#46610.
sql/table.h:
  MERGE child child_def_version is now moved from TABLE_LIST
  to MERGE engine specific data structure.
storage/myisammrg/ha_myisammrg.cc:
  Introduce an auxiliary structure to keep MERGE child name
  and definition version. A list of Mrg_child_def is created
  in ha_myisammrg::open() and reused in ha_myisammrg::add_children_list().

1 files changed, 47 insertions, 3 deletions

diff --git a/storage/myisammrg/ha_myisammrg.h b/storage/myisammrg/ha_myisammrg.h
index c3803eb584b..4ff24c69071 100644
--- a/storage/myisammrg/ha_myisammrg.h
+++ b/storage/myisammrg/ha_myisammrg.h
@@ -22,18 +22,62 @@
 
 #include <myisammrg.h>
 
+/** 
+  Represents one name of a MERGE child.
+
+  @todo: Add MYRG_SHARE and store chlidren names in the
+  share.
+*/
+
+class Mrg_child_def: public Sql_alloc
+{
+  /* Remembered MERGE child def version.  See top comment in ha_myisammrg.cc */
+  enum_table_ref_type m_child_table_ref_type;
+  ulong m_child_def_version;
+public:
+  LEX_STRING db;
+  LEX_STRING name;
+
+  /* Access MERGE child def version.  See top comment in ha_myisammrg.cc */
+  inline enum_table_ref_type get_child_table_ref_type()
+  {
+    return m_child_table_ref_type;
+  }
+  inline ulong get_child_def_version()
+  {
+    return m_child_def_version;
+  }
+  inline void set_child_def_version(enum_table_ref_type child_table_ref_type,
+                                    ulong version)
+  {
+    m_child_table_ref_type= child_table_ref_type;
+    m_child_def_version= version;
+  }
+
+  Mrg_child_def(char *db_arg, size_t db_len_arg,
+                char *table_name_arg, size_t table_name_len_arg)
+  {
+    db.str= db_arg;
+    db.length= db_len_arg;
+    name.str= table_name_arg;
+    name.length= table_name_len_arg;
+    m_child_def_version= ~0UL;
+    m_child_table_ref_type= TABLE_REF_NULL;
+  }
+};
+
+
 class ha_myisammrg: public handler
 {
   MYRG_INFO *file;
   my_bool is_cloned;                    /* This instance has been cloned */
 
- public:
+public:
   MEM_ROOT      children_mem_root;      /* mem root for children list */
+  List<Mrg_child_def> child_def_list;
   TABLE_LIST    *children_l;            /* children list */
   TABLE_LIST    **children_last_l;      /* children list end */
-  TABLE_LIST    *next_child_attach;     /* next child to attach */
   uint          test_if_locked;         /* flags from ::open() */
-  bool          need_compat_check;      /* if need compatibility check */
 
   ha_myisammrg(handlerton *hton, TABLE_SHARE *table_arg);
   ~ha_myisammrg();