Merge 10.2 into 10.3

9 files changed, 292 insertions, 307 deletions

diff --git a/sql/item_xmlfunc.cc b/sql/item_xmlfunc.cc
index 6017a0fa8af..c413969e3df 100644
--- a/sql/item_xmlfunc.cc
+++ b/sql/item_xmlfunc.cc
@@ -815,7 +815,6 @@ String *Item_nodeset_func_attributebyname::val_nodeset(String *nodeset)
 String *Item_nodeset_func_predicate::val_nodeset(String *str)
 {
   Item_nodeset_func *nodeset_func= (Item_nodeset_func*) args[0];
-  Item_func *comp_func= (Item_func*)args[1];
   uint pos= 0, size;
   prepare(str);
   size= (uint)(fltend - fltbeg);
@@ -825,7 +824,7 @@ String *Item_nodeset_func_predicate::val_nodeset(String *str)
     ((XPathFilter*)(&nodeset_func->context_cache))->append_element(flt->num,
                                                                    flt->pos,
                                                                    size);
-    if (comp_func->val_int())
+    if (args[1]->val_int())
       ((XPathFilter*)str)->append_element(flt->num, pos++);
   }
   return str;
diff --git a/sql/set_var.cc b/sql/set_var.cc
index 3711ec64aeb..eb2b9234db3 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -973,8 +973,17 @@ int set_var_default_role::check(THD *thd)
 {
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
   real_user= get_current_user(thd, user);
-  int status= acl_check_set_default_role(thd, real_user->host.str, real_user->user.str);
-  return status;
+  real_role= role.str;
+  if (role.str == current_role.str)
+  {
+    if (!thd->security_ctx->priv_role[0])
+      real_role= "NONE";
+    else
+      real_role= thd->security_ctx->priv_role;
+  }
+
+  return acl_check_set_default_role(thd, real_user->host.str,
+                                    real_user->user.str, real_role);
 #else
   return 0;
 #endif
@@ -985,7 +994,8 @@ int set_var_default_role::update(THD *thd)
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
   Reprepare_observer *save_reprepare_observer= thd->m_reprepare_observer;
   thd->m_reprepare_observer= 0;
-  int res= acl_set_default_role(thd, real_user->host.str, real_user->user.str, role.str);
+  int res= acl_set_default_role(thd, real_user->host.str, real_user->user.str,
+                                real_role);
   thd->m_reprepare_observer= save_reprepare_observer;
   return res;
 #else
diff --git a/sql/set_var.h b/sql/set_var.h
index 7530d3eaff5..12e025e4696 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -1,7 +1,7 @@
 #ifndef SET_VAR_INCLUDED
 #define SET_VAR_INCLUDED
 /* Copyright (c) 2002, 2013, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2014, SkySQL Ab.
+   Copyright (c) 2009, 2020, MariaDB
 
    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
@@ -352,6 +352,7 @@ class set_var_default_role: public set_var_base
 {
   LEX_USER *user, *real_user;
   LEX_CSTRING role;
+  const char *real_role;
 public:
   set_var_default_role(LEX_USER *user_arg, LEX_CSTRING role_arg) :
     user(user_arg), role(role_arg) {}
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index e29fd0345da..58711d0a9d0 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2018, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2018, MariaDB
+   Copyright (c) 2009, 2020, MariaDB
 
    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
@@ -84,7 +84,6 @@ LEX_CSTRING current_user= { STRING_WITH_LEN("*current_user") };
 LEX_CSTRING current_role= { STRING_WITH_LEN("*current_role") };
 LEX_CSTRING current_user_and_current_role= { STRING_WITH_LEN("*current_user_and_current_role") };
 
-
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
 static plugin_ref old_password_plugin;
 #endif
@@ -2520,8 +2519,43 @@ bool acl_getroot(Security_context *sctx, const char *user, const char *host,
   DBUG_RETURN(res);
 }
 
-static int check_user_can_set_role(const char *user, const char *host,
-                      const char *ip, const char *rolename, ulonglong *access)
+static int check_role_is_granted_callback(ACL_USER_BASE *grantee, void *data)
+{
+  LEX_CSTRING *rolename= static_cast<LEX_CSTRING *>(data);
+  if (rolename->length == grantee->user.length &&
+      !strcmp(rolename->str, grantee->user.str))
+    return -1; // End search, we've found our role.
+
+  /* Keep looking, we haven't found our role yet. */
+  return 0;
+}
+
+/*
+  unlike find_user_exact and find_user_wild,
+  this function finds anonymous users too, it's when a
+  user is not empty, but priv_user (acl_user->user) is empty.
+*/
+static ACL_USER *find_user_or_anon(const char *host, const char *user, const char *ip)
+{
+  ACL_USER *result= NULL;
+  mysql_mutex_assert_owner(&acl_cache->lock);
+  for (uint i=0; i < acl_users.elements; i++)
+  {
+    ACL_USER *acl_user_tmp= dynamic_element(&acl_users, i, ACL_USER*);
+    if ((!acl_user_tmp->user.str ||
+         !strcmp(user, acl_user_tmp->user.str)) &&
+         compare_hostname(&acl_user_tmp->host, host, ip))
+    {
+      result= acl_user_tmp;
+      break;
+    }
+  }
+  return result;
+}
+
+static int check_user_can_set_role(THD *thd, const char *user, const char *host,
+                                   const char *ip, const char *rolename,
+                                   ulonglong *access)
 {
   ACL_ROLE *role;
   ACL_USER_BASE *acl_user_base;
@@ -2538,10 +2572,7 @@ static int check_user_can_set_role(const char *user, const char *host,
     /* get the current user */
     acl_user= find_user_wild(host, user, ip);
     if (acl_user == NULL)
-    {
-      my_error(ER_INVALID_CURRENT_USER, MYF(0));
-      result= -1;
-    }
+      result= ER_INVALID_CURRENT_USER;
     else if (access)
       *access= acl_user->access;
 
@@ -2551,9 +2582,9 @@ static int check_user_can_set_role(const char *user, const char *host,
   role= find_acl_role(rolename);
 
   /* According to SQL standard, the same error message must be presented */
-  if (role == NULL) {
-    my_error(ER_INVALID_ROLE, MYF(0), rolename);
-    result= -1;
+  if (role == NULL)
+  {
+    result= ER_INVALID_ROLE;
     goto end;
   }
 
@@ -2574,7 +2605,6 @@ static int check_user_can_set_role(const char *user, const char *host,
   /* According to SQL standard, the same error message must be presented */
   if (!is_granted)
   {
-    my_error(ER_INVALID_ROLE, MYF(0), rolename);
     result= 1;
     goto end;
   }
@@ -2583,17 +2613,66 @@ static int check_user_can_set_role(const char *user, const char *host,
   {
     *access = acl_user->access | role->access;
   }
+
 end:
   mysql_mutex_unlock(&acl_cache->lock);
-  return result;
 
+  /* We present different error messages depending if the user has sufficient
+     privileges to know if the INVALID_ROLE exists. */
+  switch (result)
+  {
+    case ER_INVALID_CURRENT_USER:
+      my_error(ER_INVALID_CURRENT_USER, MYF(0), rolename);
+      break;
+    case ER_INVALID_ROLE:
+      /* Role doesn't exist at all */
+      my_error(ER_INVALID_ROLE, MYF(0), rolename);
+      break;
+    case 1:
+      StringBuffer<1024> c_usr;
+      LEX_CSTRING role_lex;
+      /* First, check if current user can see mysql database. */
+      bool read_access= !check_access(thd, SELECT_ACL, "mysql", NULL, NULL, 1, 1);
+
+      role_lex.str= rolename;
+      role_lex.length= strlen(rolename);
+      mysql_mutex_lock(&acl_cache->lock);
+      ACL_USER *cur_user= find_user_or_anon(thd->security_ctx->priv_host,
+                                            thd->security_ctx->priv_user,
+                                            thd->security_ctx->ip);
+
+      /* If the current user does not have select priv to mysql database,
+         see if the current user can discover the role if it was granted to him.
+      */
+      if (cur_user && (read_access ||
+                       traverse_role_graph_down(cur_user, &role_lex,
+                                                check_role_is_granted_callback,
+                                                NULL) == -1))
+      {
+        /* Role is not granted but current user can see the role */
+        c_usr.append(user, strlen(user));
+        c_usr.append('@');
+        c_usr.append(host, strlen(host));
+        my_printf_error(ER_INVALID_ROLE, "User %`s has not been granted role %`s",
+                        MYF(0), c_usr.c_ptr(), rolename);
+      }
+      else
+      {
+        /* Role is not granted and current user cannot see the role */
+        my_error(ER_INVALID_ROLE, MYF(0), rolename);
+      }
+      mysql_mutex_unlock(&acl_cache->lock);
+      break;
+  }
+
+  return result;
 }
 
+
 int acl_check_setrole(THD *thd, const char *rolename, ulonglong *access)
 {
-    /* Yes! priv_user@host. Don't ask why - that's what check_access() does. */
-  return check_user_can_set_role(thd->security_ctx->priv_user,
-        thd->security_ctx->host, thd->security_ctx->ip, rolename, access);
+  return check_user_can_set_role(thd, thd->security_ctx->priv_user,
+           thd->security_ctx->host, thd->security_ctx->ip, rolename, access);
 }
 
 
@@ -3374,9 +3453,12 @@ WSREP_ERROR_LABEL:
   DBUG_RETURN(result);
 }
 
-int acl_check_set_default_role(THD *thd, const char *host, const char *user)
+int acl_check_set_default_role(THD *thd, const char *host, const char *user,
+                               const char *role)
 {
-  return check_alter_user(thd, host, user);
+  DBUG_ENTER("acl_check_set_default_role");
+  DBUG_RETURN(check_alter_user(thd, host, user) ||
+              check_user_can_set_role(thd, user, host, NULL, role, NULL));
 }
 
 int acl_set_default_role(THD *thd, const char *host, const char *user,
@@ -3397,16 +3479,6 @@ int acl_set_default_role(THD *thd, const char *host, const char *user,
   DBUG_PRINT("enter",("host: '%s'  user: '%s'  rolename: '%s'",
                       safe_str(user), safe_str(host), safe_str(rolename)));
 
-  if (rolename == current_role.str) {
-    if (!thd->security_ctx->priv_role[0])
-      rolename= "NONE";
-    else
-      rolename= thd->security_ctx->priv_role;
-  }
-
-  if (check_user_can_set_role(user, host, host, rolename, NULL))
-    DBUG_RETURN(result);
-
   if (!strcasecmp(rolename, "NONE"))
     clear_role= TRUE;
 
@@ -3571,31 +3643,6 @@ bool is_acl_user(const char *host, const char *user)
   return res;
 }
 
-
-/*
-  unlike find_user_exact and find_user_wild,
-  this function finds anonymous users too, it's when a
-  user is not empty, but priv_user (acl_user->user) is empty.
-*/
-static ACL_USER *find_user_or_anon(const char *host, const char *user, const char *ip)
-{
-  ACL_USER *result= NULL;
-  mysql_mutex_assert_owner(&acl_cache->lock);
-  for (uint i=0; i < acl_users.elements; i++)
-  {
-    ACL_USER *acl_user_tmp= dynamic_element(&acl_users, i, ACL_USER*);
-    if ((!acl_user_tmp->user.str ||
-         !strcmp(user, acl_user_tmp->user.str)) &&
-         compare_hostname(&acl_user_tmp->host, host, ip))
-    {
-      result= acl_user_tmp;
-      break;
-    }
-  }
-  return result;
-}
-
-
 /*
   Find first entry that matches the specified user@host pair
 */
@@ -3900,7 +3947,7 @@ static bool test_if_create_new_users(THD *thd)
     if (!(db_access & INSERT_ACL))
     {
       if (check_grant(thd, INSERT_ACL, &tl, FALSE, UINT_MAX, TRUE))
-	create_new_users=0;
+        create_new_users=0;
     }
   }
   return create_new_users;
@@ -9225,17 +9272,6 @@ void get_mqh(const char *user, const char *host, USER_CONN *uc)
   mysql_mutex_unlock(&acl_cache->lock);
 }
 
-static int check_role_is_granted_callback(ACL_USER_BASE *grantee, void *data)
-{
-  LEX_CSTRING *rolename= static_cast<LEX_CSTRING *>(data);
-  if (rolename->length == grantee->user.length &&
-      !strcmp(rolename->str, grantee->user.str))
-    return -1; // End search, we've found our role.
-
-  /* Keep looking, we haven't found our role yet. */
-  return 0;
-}
-
 /*
   Modify a privilege table.
 
@@ -11125,7 +11161,7 @@ acl_check_proxy_grant_access(THD *thd, const char *host, const char *user,
     Security context in THD contains two pairs of (user,host):
     1. (user,host) pair referring to inbound connection.
     2. (priv_user,priv_host) pair obtained from mysql.user table after doing
-        authnetication of incoming connection.
+        authentication of incoming connection.
     Privileges should be checked wrt (priv_user, priv_host) tuple, because
     (user,host) pair obtained from inbound connection may have different
     values than what is actually stored in mysql.user table and while granting
@@ -11544,7 +11580,7 @@ int fill_schema_user_privileges(THD *thd, TABLE_LIST *tables, COND *cond)
       ulong j,test_access= want_access & ~GRANT_ACL;
       for (priv_id=0, j = SELECT_ACL;j <= GLOBAL_ACLS; priv_id++,j <<= 1)
       {
-	if (test_access & j)
+        if (test_access & j)
         {
           if (update_schema_privilege(thd, table, buff, 0, 0, 0, 0,
                                       command_array[priv_id],
diff --git a/sql/sql_acl.h b/sql/sql_acl.h
index 7989367ec44..dc8a085c96c 100644
--- a/sql/sql_acl.h
+++ b/sql/sql_acl.h
@@ -2,7 +2,7 @@
 #define SQL_ACL_INCLUDED
 
 /* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
-   Copyright (c) 2017, MariaDB Corporation.
+   Copyright (c) 2017, 2020, MariaDB Corporation.
 
    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
@@ -417,7 +417,8 @@ bool acl_check_proxy_grant_access (THD *thd, const char *host, const char *user,
                                    bool with_grant);
 int acl_setrole(THD *thd, const char *rolename, ulonglong access);
 int acl_check_setrole(THD *thd, const char *rolename, ulonglong *access);
-int acl_check_set_default_role(THD *thd, const char *host, const char *user);
+int acl_check_set_default_role(THD *thd, const char *host, const char *user,
+                               const char *role);
 int acl_set_default_role(THD *thd, const char *host, const char *user,
                          const char *rolename);
 
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index 83013b8b1e7..b65f460c896 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -1,5 +1,5 @@
 /* Copyright (C) 2009 MySQL AB
-   Copyright (c) 2019, MariaDB Corporation.
+   Copyright (c) 2019, 2020, MariaDB Corporation.
 
    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
@@ -2214,27 +2214,13 @@ static int alloc_statistics_for_table_share(THD* thd, TABLE_SHARE *table_share)
 
   DBUG_ENTER("alloc_statistics_for_table_share");
 
-  DEBUG_SYNC(thd, "statistics_mem_alloc_start1");
-  DEBUG_SYNC(thd, "statistics_mem_alloc_start2");
-
-  mysql_mutex_lock(&table_share->LOCK_share);
-
-  if (stats_cb->stats_can_be_read)
-  {
-    mysql_mutex_unlock(&table_share->LOCK_share);
-    DBUG_RETURN(0);
-  }
-
   Table_statistics *table_stats= stats_cb->table_stats;
   if (!table_stats)
   {
     table_stats=  (Table_statistics *) alloc_root(&stats_cb->mem_root,
                                                   sizeof(Table_statistics));
     if (!table_stats)
-    {
-      mysql_mutex_unlock(&table_share->LOCK_share);
       DBUG_RETURN(1);
-    }
     memset(table_stats, 0, sizeof(Table_statistics));
     stats_cb->table_stats= table_stats;
   }
@@ -2300,89 +2286,11 @@ static int alloc_statistics_for_table_share(THD* thd, TABLE_SHARE *table_share)
       }
     }   
   }
-
-  if (column_stats && index_stats && idx_avg_frequency)
-    stats_cb->stats_can_be_read= TRUE;
-
-  mysql_mutex_unlock(&table_share->LOCK_share);
-
-  DBUG_RETURN(0);
+  DBUG_RETURN(column_stats && index_stats && idx_avg_frequency ? 0 : 1);
 }
 
 
 /**
-  @brief 
-  Allocate memory for the histogram used by a table share
-
-  @param
-  thd         Thread handler
-  @param
-  table_share Table share for which the memory for histogram data is allocated
-  @param
-  is_safe     TRUE <-> at any time only one thread can perform the function
-
-  @note
-  The function allocates the memory for the histogram built for a table in the
-  table's share memory with the intention to read the data there from the
-  system persistent statistical table mysql.column_stats,
-  The memory is allocated in the table_share's mem_root.
-  If the parameter is_safe is TRUE then it is guaranteed that at any given time
-  only one thread is executed the code of the function.
-
-  @retval
-  0     If the memory for all statistical data has been successfully allocated  
-  @retval
-  1     Otherwise
-
-  @note
-  Currently the function always is called with the parameter is_safe set
-  to FALSE. 
-*/      
-
-static
-int alloc_histograms_for_table_share(THD* thd, TABLE_SHARE *table_share, 
-                                     bool is_safe)
-{
-  TABLE_STATISTICS_CB *stats_cb= &table_share->stats_cb;
-
-  DBUG_ENTER("alloc_histograms_for_table_share");
-
-  if (!is_safe)
-    mysql_mutex_lock(&table_share->LOCK_share);
-
-  if (stats_cb->histograms_can_be_read)
-  {
-    if (!is_safe)
-      mysql_mutex_unlock(&table_share->LOCK_share);
-    DBUG_RETURN(0);
-  }
-
-  Table_statistics *table_stats= stats_cb->table_stats;
-  ulong total_hist_size= table_stats->total_hist_size;
-
-  if (total_hist_size && !table_stats->histograms)
-  {
-    uchar *histograms= (uchar *) alloc_root(&stats_cb->mem_root,
-                                            total_hist_size);
-    if (!histograms)
-    {
-      if (!is_safe)
-        mysql_mutex_unlock(&table_share->LOCK_share);
-      DBUG_RETURN(1);
-    }
-    memset(histograms, 0, total_hist_size);
-    table_stats->histograms= histograms;
-    stats_cb->histograms_can_be_read= TRUE;
-  }
-
-  if (!is_safe)
-    mysql_mutex_unlock(&table_share->LOCK_share);
-
-  DBUG_RETURN(0);
-
-}
-
-/**
   @brief
   Initialize the aggregation fields to collect statistics on a column
 
@@ -2923,15 +2831,26 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
   Field **field_ptr;
   KEY *key_info, *key_info_end;
   TABLE_SHARE *table_share= table->s;
-  Table_statistics *read_stats= table_share->stats_cb.table_stats;
   enum_check_fields old_check_level= thd->count_cuted_fields;
 
   DBUG_ENTER("read_statistics_for_table");
+  DEBUG_SYNC(thd, "statistics_mem_alloc_start1");
+  DEBUG_SYNC(thd, "statistics_mem_alloc_start2");
+
+  if (!table_share->stats_cb.start_stats_load())
+    DBUG_RETURN(table_share->stats_cb.stats_are_ready() ? 0 : 1);
+
+  if (alloc_statistics_for_table_share(thd, table_share))
+  {
+    table_share->stats_cb.abort_stats_load();
+    DBUG_RETURN(1);
+  }
 
   /* Don't write warnings for internal field conversions */
   thd->count_cuted_fields= CHECK_FIELD_IGNORE;
 
   /* Read statistics from the statistical table table_stats */
+  Table_statistics *read_stats= table_share->stats_cb.table_stats;
   stat_table= stat_tables[TABLE_STAT].table;
   Table_stat table_stat(stat_table, table);
   table_stat.set_key_fields();
@@ -2948,7 +2867,7 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
     column_stat.get_stat_values();
     total_hist_size+= table_field->read_stats->histogram.get_size();
   }
-  read_stats->total_hist_size= total_hist_size;
+  table_share->stats_cb.total_hist_size= total_hist_size;
 
   /* Read statistics from the statistical table index_stats */
   stat_table= stat_tables[INDEX_STAT].table;
@@ -3010,9 +2929,8 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
     }
   }
 
-  table->stats_is_read= TRUE;
   thd->count_cuted_fields= old_check_level;
-
+  table_share->stats_cb.end_stats_load();
   DBUG_RETURN(0);
 }
 
@@ -3052,71 +2970,6 @@ void delete_stat_values_for_table_share(TABLE_SHARE *table_share)
 
 /**
   @brief
-  Check whether any statistics is to be read for tables from a table list
-
-  @param
-  thd         The thread handle
-  @param
-  tables      The tables list for whose tables the check is to be done
-
-  @details
-  The function checks whether for any of the tables opened and locked for
-  a statement statistics from statistical tables is needed to be read.
-
-  @retval
-  TRUE        statistics for any of the tables is needed to be read 
-  @retval
-  FALSE       Otherwise
-*/
-
-static
-bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
-{
-  if (!tables)
-    return FALSE;
-
-  /* 
-    Do not read statistics for any query that explicity involves
-    statistical tables, failure to to do so we may end up
-    in a deadlock.
-  */
-
-  for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
-  {
-    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
-    {
-      TABLE_SHARE *table_share= tl->table->s;
-      if (table_share && 
-          table_share->table_category != TABLE_CATEGORY_USER
-          && is_stat_table(&tl->db, &tl->alias))
-        return FALSE;
-    }
-  }
-
-  for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
-  {
-    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
-    {
-      TABLE_SHARE *table_share= tl->table->s;
-      if (table_share && 
-          table_share->stats_cb.stats_can_be_read &&
-          (!table_share->stats_cb.stats_is_read ||
-           (!table_share->stats_cb.histograms_are_read &&
-            thd->variables.optimizer_use_condition_selectivity > 3)))
-        return TRUE;
-      if (table_share->stats_cb.stats_is_read)
-        tl->table->stats_is_read= TRUE;
-      if (table_share->stats_cb.histograms_are_read)
-        tl->table->histograms_are_read= TRUE;
-    } 
-  }
-
-  return FALSE;
-}
-
-
-/**
-  @brief
   Read histogram for a table from the persistent statistical tables
 
   @param
@@ -3150,26 +3003,25 @@ bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
 static
 int read_histograms_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
 {
-  TABLE_SHARE *table_share= table->s;
-  
+  TABLE_STATISTICS_CB *stats_cb= &table->s->stats_cb;
   DBUG_ENTER("read_histograms_for_table");
 
-  if (!table_share->stats_cb.histograms_can_be_read)
+  if (stats_cb->start_histograms_load())
   {
-    (void) alloc_histograms_for_table_share(thd, table_share, FALSE);
-  }
-  if (table_share->stats_cb.histograms_can_be_read &&
-      !table_share->stats_cb.histograms_are_read)
-  {
-    Field **field_ptr;
-    uchar *histogram= table_share->stats_cb.table_stats->histograms;
-    TABLE *stat_table= stat_tables[COLUMN_STAT].table;
-    Column_stat column_stat(stat_table, table);
-    for (field_ptr= table_share->field; *field_ptr; field_ptr++)
+    uchar *histogram= (uchar *) alloc_root(&stats_cb->mem_root,
+                                           stats_cb->total_hist_size);
+    if (!histogram)
+    {
+      stats_cb->abort_histograms_load();
+      DBUG_RETURN(1);
+    }
+    memset(histogram, 0, stats_cb->total_hist_size);
+
+    Column_stat column_stat(stat_tables[COLUMN_STAT].table, table);
+    for (Field **field_ptr= table->s->field; *field_ptr; field_ptr++)
     {
       Field *table_field= *field_ptr;
-      uint hist_size= table_field->read_stats->histogram.get_size();
-      if (hist_size)
+      if (uint hist_size= table_field->read_stats->histogram.get_size())
       {
         column_stat.set_key_fields(table_field);
         table_field->read_stats->histogram.set_values(histogram);
@@ -3177,8 +3029,9 @@ int read_histograms_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
         histogram+= hist_size;
       }
     }
+    stats_cb->end_histograms_load();
   }
- 
+  table->histograms_are_read= true;
   DBUG_RETURN(0);
 }
 
@@ -3226,6 +3079,23 @@ int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables)
 }
 
 
+static void dump_stats_from_share_to_table(TABLE *table)
+{
+  TABLE_SHARE *table_share= table->s;
+  KEY *key_info= table_share->key_info;
+  KEY *key_info_end= key_info + table_share->keys;
+  KEY *table_key_info= table->key_info;
+  for ( ; key_info < key_info_end; key_info++, table_key_info++)
+    table_key_info->read_stats= key_info->read_stats;
+
+  Field **field_ptr= table_share->field;
+  Field **table_field_ptr= table->field;
+  for ( ; *field_ptr; field_ptr++, table_field_ptr++)
+    (*table_field_ptr)->read_stats= (*field_ptr)->read_stats;
+  table->stats_is_read= true;
+}
+
+
 int read_statistics_for_tables(THD *thd, TABLE_LIST *tables)
 {
   TABLE_LIST stat_tables[STATISTICS_TABLES];
@@ -3236,38 +3106,42 @@ int read_statistics_for_tables(THD *thd, TABLE_LIST *tables)
   if (thd->bootstrap || thd->variables.use_stat_tables == NEVER)
     DBUG_RETURN(0);
 
+  bool found_stat_table= false;
+  bool statistics_for_tables_is_needed= false;
+
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {
-    if (tl->table)
+    TABLE_SHARE *table_share;
+    if (!tl->is_view_or_derived() && tl->table && (table_share= tl->table->s) &&
+        table_share->tmp_table == NO_TMP_TABLE)
     {
-      TABLE_SHARE *table_share= tl->table->s;
-      if (table_share && table_share->table_category == TABLE_CATEGORY_USER &&
-          table_share->tmp_table == NO_TMP_TABLE)
+      if (table_share->table_category == TABLE_CATEGORY_USER)
       {
-        if (table_share->stats_cb.stats_can_be_read ||
-            !alloc_statistics_for_table_share(thd, table_share))
+        if (table_share->stats_cb.stats_are_ready())
         {
-          if (table_share->stats_cb.stats_can_be_read)
-          {
-            KEY *key_info= table_share->key_info;
-            KEY *key_info_end= key_info + table_share->keys;
-            KEY *table_key_info= tl->table->key_info;
-            for ( ; key_info < key_info_end; key_info++, table_key_info++)
-              table_key_info->read_stats= key_info->read_stats;
-            Field **field_ptr= table_share->field;
-            Field **table_field_ptr= tl->table->field;
-            for ( ; *field_ptr; field_ptr++, table_field_ptr++)
-              (*table_field_ptr)->read_stats= (*field_ptr)->read_stats;
-            tl->table->stats_is_read= table_share->stats_cb.stats_is_read;
-          }
+          if (!tl->table->stats_is_read)
+            dump_stats_from_share_to_table(tl->table);
+          tl->table->histograms_are_read=
+            table_share->stats_cb.histograms_are_ready();
+          if (table_share->stats_cb.histograms_are_ready() ||
+              thd->variables.optimizer_use_condition_selectivity <= 3)
+            continue;
         }
+        statistics_for_tables_is_needed= true;
       }
+      else if (is_stat_table(&tl->db, &tl->alias))
+        found_stat_table= true;
     }
   }
 
   DEBUG_SYNC(thd, "statistics_read_start");
 
-  if (!statistics_for_tables_is_needed(thd, tables))
+  /*
+    Do not read statistics for any query that explicity involves
+    statistical tables, failure to to do so we may end up
+    in a deadlock.
+  */
+  if (found_stat_table || !statistics_for_tables_is_needed)
     DBUG_RETURN(0);
 
   if (open_stat_tables(thd, stat_tables, &open_tables_backup, FALSE))
@@ -3275,32 +3149,22 @@ int read_statistics_for_tables(THD *thd, TABLE_LIST *tables)
 
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {
-    if (!tl->is_view_or_derived() && !is_temporary_table(tl) && tl->table)
-    { 
-      TABLE_SHARE *table_share= tl->table->s;
-      if (table_share && !(table_share->table_category == TABLE_CATEGORY_USER))
-        continue;
-
-      if (table_share && 
-          table_share->stats_cb.stats_can_be_read &&
-	  !table_share->stats_cb.stats_is_read)
+    TABLE_SHARE *table_share;
+    if (!tl->is_view_or_derived() && tl->table && (table_share= tl->table->s) &&
+        table_share->tmp_table == NO_TMP_TABLE &&
+        table_share->table_category == TABLE_CATEGORY_USER)
+    {
+      if (!tl->table->stats_is_read)
       {
-        (void) read_statistics_for_table(thd, tl->table, stat_tables);
-        table_share->stats_cb.stats_is_read= TRUE;
+        if (!read_statistics_for_table(thd, tl->table, stat_tables))
+          dump_stats_from_share_to_table(tl->table);
+        else
+          continue;
       }
-      if (table_share->stats_cb.stats_is_read)
-        tl->table->stats_is_read= TRUE;
-      if (thd->variables.optimizer_use_condition_selectivity > 3 && 
-          table_share && table_share->stats_cb.stats_can_be_read &&
-          !table_share->stats_cb.histograms_are_read)
-      {
+      if (thd->variables.optimizer_use_condition_selectivity > 3)
         (void) read_histograms_for_table(thd, tl->table, stat_tables);
-        table_share->stats_cb.histograms_are_read= TRUE;
-      }
-      if (table_share->stats_cb.histograms_are_read)
-        tl->table->histograms_are_read= TRUE;
     }
-  }  
+  }
 
   close_system_tables(thd, &open_tables_backup);
 
diff --git a/sql/sql_statistics.h b/sql/sql_statistics.h
index a69dd340dd7..c6b4fed30fa 100644
--- a/sql/sql_statistics.h
+++ b/sql/sql_statistics.h
@@ -268,7 +268,6 @@ public:
   Column_statistics *column_stats;  /* Array of statistical data for columns */
   Index_statistics *index_stats;    /* Array of statistical data for indexes */
   ulong *idx_avg_frequency;   /* Array of records per key for index prefixes */
-  ulong total_hist_size;            /* Total size of all histograms */
   uchar *histograms;                /* Sequence of histograms       */                    
 };
 
diff --git a/sql/table.cc b/sql/table.cc
index 7d09985094c..1877c3b7c76 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -443,10 +443,6 @@ void TABLE_SHARE::destroy()
   delete_stat_values_for_table_share(this);
   delete sequence;
   free_root(&stats_cb.mem_root, MYF(0));
-  stats_cb.stats_can_be_read= FALSE;
-  stats_cb.stats_is_read= FALSE;
-  stats_cb.histograms_can_be_read= FALSE;
-  stats_cb.histograms_are_read= FALSE;
 
   /* The mutexes are initialized only for shares that are part of the TDC */
   if (tmp_table == NO_TMP_TABLE)
diff --git a/sql/table.h b/sql/table.h
index 940f135bcf1..2bad6cbf32f 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -581,15 +581,94 @@ enum open_frm_error {
   from persistent statistical tables
 */
 
-struct TABLE_STATISTICS_CB
+class TABLE_STATISTICS_CB
 {
+  class Statistics_state
+  {
+    enum state_codes
+    {
+      EMPTY,   /** data is not loaded */
+      LOADING, /** data is being loaded in some connection */
+      READY    /** data is loaded and available for use */
+    };
+    int32 state;
+
+  public:
+    /** No state copy */
+    Statistics_state &operator=(const Statistics_state &) { return *this; }
+
+    /** Checks if data loading have been completed */
+    bool is_ready() const
+    {
+      return my_atomic_load32_explicit(const_cast<int32*>(&state),
+                                       MY_MEMORY_ORDER_ACQUIRE) == READY;
+    }
+
+    /**
+      Sets mutual exclusion for data loading
+
+      If stats are in LOADING state, waits until state change.
+
+      @return
+        @retval true atomic EMPTY -> LOADING transfer completed, ok to load
+        @retval false stats are in READY state, no need to load
+    */
+    bool start_load()
+    {
+      for (;;)
+      {
+        int32 expected= EMPTY;
+        if (my_atomic_cas32_weak_explicit(&state, &expected, LOADING,
+                                          MY_MEMORY_ORDER_RELAXED,
+                                          MY_MEMORY_ORDER_RELAXED))
+          return true;
+        if (expected == READY)
+          return false;
+        (void) LF_BACKOFF();
+      }
+    }
+
+    /** Marks data available for subsequent use */
+    void end_load()
+    {
+      DBUG_ASSERT(my_atomic_load32_explicit(&state, MY_MEMORY_ORDER_RELAXED) ==
+                  LOADING);
+      my_atomic_store32_explicit(&state, READY, MY_MEMORY_ORDER_RELEASE);
+    }
+
+    /** Restores empty state on error (e.g. OOM) */
+    void abort_load()
+    {
+      DBUG_ASSERT(my_atomic_load32_explicit(&state, MY_MEMORY_ORDER_RELAXED) ==
+                  LOADING);
+      my_atomic_store32_explicit(&state, EMPTY, MY_MEMORY_ORDER_RELAXED);
+    }
+  };
+
+  class Statistics_state stats_state;
+  class Statistics_state hist_state;
+
+public:
   MEM_ROOT  mem_root; /* MEM_ROOT to allocate statistical data for the table */
   Table_statistics *table_stats; /* Structure to access the statistical data */
-  bool stats_can_be_read;        /* Memory for statistical data is allocated */
-  bool stats_is_read;            /* Statistical data for table has been read
-                                    from statistical tables */
-  bool histograms_can_be_read;
-  bool histograms_are_read;   
+  ulong total_hist_size;         /* Total size of all histograms */
+
+  bool histograms_are_ready() const
+  {
+    return !total_hist_size || hist_state.is_ready();
+  }
+
+  bool start_histograms_load()
+  {
+    return total_hist_size && hist_state.start_load();
+  }
+
+  void end_histograms_load() { hist_state.end_load(); }
+  void abort_histograms_load() { hist_state.abort_load(); }
+  bool stats_are_ready() const { return stats_state.is_ready(); }
+  bool start_stats_load() { return stats_state.start_load(); }
+  void end_stats_load() { stats_state.end_load(); }
+  void abort_stats_load() { stats_state.abort_load(); }
 };
 
 /**