Backport of:

----------------------------------------------------------
revno: 2617.69.24
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 19:22:05 +0400
message:
  A pre-requisite for a fix for Bug#42546 "Backup: RESTORE fails, thinking it
  finds an existing table"
  Back-port from WL 148 "Foreign keys" feature tree a patch
  that introduced Prelocking_strategy class -- a way to parameterize
  open_tables() behaviour, implemented by Dmitry Lenev.

(Part of WL#4284).

sql/sql_base.cc:
  Implement different prelocking strategies. Use an instance of
  prelocking_strategy in open_tables().
sql/sql_class.h:
  Add declarations for class Prelocking_strategy.
sql/sql_lex.h:
  Add a helper method to access last table of the global table list
  (lex->query_tables).
sql/sql_parse.cc:
  Use a special prelocking strategy when locking tables for LOCK TABLES.
sql/sql_table.cc:
  Use normal open_and_lock_tables_derived() in ALTER TABLE.
sql/sql_yacc.yy:
  Modify the grammar to not pollute the global table list with tables
  that should not be opened.

1 files changed, 50 insertions, 16 deletions

diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 24800f805d0..577c60b4c10 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -1766,6 +1766,7 @@ create:
             lex->create_info.default_table_charset= NULL;
             lex->name.str= 0;
             lex->name.length= 0;
+            lex->create_last_non_select_table= lex->last_table();
           }
           create2
           {
@@ -1788,7 +1789,8 @@ create:
             lex->sql_command= SQLCOM_CREATE_INDEX;
             if (!lex->current_select->add_table_to_list(lex->thd, $7,
                                                         NULL,
-                                                        TL_OPTION_UPDATING))
+                                                        TL_OPTION_UPDATING,
+                                                        TL_WRITE_ALLOW_READ))
               MYSQL_YYABORT;
             lex->alter_info.reset();
             lex->alter_info.flags= ALTER_ADD_INDEX;
@@ -3952,7 +3954,7 @@ create2:
         ;
 
 create2a:
-          field_list ')' opt_create_table_options
+          create_field_list ')' opt_create_table_options
           opt_partitioning
           create3 {}
         |  opt_partitioning
@@ -4802,19 +4804,30 @@ create_table_option:
             Lex->create_info.row_type= $3;
             Lex->create_info.used_fields|= HA_CREATE_USED_ROW_FORMAT;
           }
-        | UNION_SYM opt_equal '(' opt_table_list ')'
+        | UNION_SYM opt_equal
+          {
+            Lex->select_lex.table_list.save_and_clear(&Lex->save_list);
+          }
+          '(' opt_table_list ')'
           {
-            /* Move the union list to the merge_list */
+            /*
+              Move the union list to the merge_list and exclude its tables
+              from the global list.
+            */
             LEX *lex=Lex;
-            TABLE_LIST *table_list= lex->select_lex.get_table_list();
             lex->create_info.merge_list= lex->select_lex.table_list;
-            lex->create_info.merge_list.elements--;
-            lex->create_info.merge_list.first=
-              (uchar*) (table_list->next_local);
-            lex->select_lex.table_list.elements=1;
-            lex->select_lex.table_list.next=
-              (uchar**) &(table_list->next_local);
-            table_list->next_local= 0;
+            lex->select_lex.table_list= lex->save_list;
+            /*
+              When excluding union list from the global list we assume that
+              elements of the former immediately follow elements which represent
+              table being created/altered and parent tables.
+            */
+            TABLE_LIST *last_non_sel_table= lex->create_last_non_select_table;
+            DBUG_ASSERT(last_non_sel_table->next_global ==
+                        (TABLE_LIST *)lex->create_info.merge_list.first);
+            last_non_sel_table->next_global= 0;
+            Lex->query_tables_last= &last_non_sel_table->next_global;
+
             lex->create_info.used_fields|= HA_CREATE_USED_UNION;
           }
         | default_charset
@@ -4952,6 +4965,14 @@ udf_type:
         | INT_SYM {$$ = (int) INT_RESULT; }
         ;
 
+
+create_field_list:
+        field_list
+        {
+          Lex->create_last_non_select_table= Lex->last_table();
+        }
+        ;
+
 field_list:
           field_list_item
         | field_list ',' field_list_item
@@ -5743,7 +5764,8 @@ alter:
             lex->sql_command= SQLCOM_ALTER_TABLE;
             lex->duplicates= DUP_ERROR; 
             if (!lex->select_lex.add_table_to_list(thd, $4, NULL,
-                                                   TL_OPTION_UPDATING))
+                                                   TL_OPTION_UPDATING,
+                                                   TL_WRITE_ALLOW_READ))
               MYSQL_YYABORT;
             lex->col_list.empty();
             lex->select_lex.init_order();
@@ -5756,6 +5778,7 @@ alter:
             lex->alter_info.reset();
             lex->no_write_to_binlog= 0;
             lex->create_info.storage_media= HA_SM_DEFAULT;
+            lex->create_last_non_select_table= lex->last_table();
           }
           alter_commands
           {}
@@ -6139,12 +6162,16 @@ add_column:
         ;
 
 alter_list_item:
-          add_column column_def opt_place { }
+          add_column column_def opt_place
+          {
+            Lex->create_last_non_select_table= Lex->last_table();
+          }
         | ADD key_def
           {
+            Lex->create_last_non_select_table= Lex->last_table();
             Lex->alter_info.flags|= ALTER_ADD_INDEX;
           }
-        | add_column '(' field_list ')'
+        | add_column '(' create_field_list ')'
           {
             Lex->alter_info.flags|= ALTER_ADD_COLUMN | ALTER_ADD_INDEX;
           }
@@ -6155,6 +6182,9 @@ alter_list_item:
             lex->alter_info.flags|= ALTER_CHANGE_COLUMN;
           }
           field_spec opt_place
+          {
+            Lex->create_last_non_select_table= Lex->last_table();
+          }
         | MODIFY_SYM opt_column field_ident
           {
             LEX *lex=Lex;
@@ -6177,6 +6207,9 @@ alter_list_item:
               MYSQL_YYABORT;
           }
           opt_place
+          {
+            Lex->create_last_non_select_table= Lex->last_table();
+          }
         | DROP opt_column field_ident opt_restrict
           {
             LEX *lex=Lex;
@@ -9607,7 +9640,8 @@ drop:
             lex->alter_info.flags= ALTER_DROP_INDEX;
             lex->alter_info.drop_list.push_back(ad);
             if (!lex->current_select->add_table_to_list(lex->thd, $5, NULL,
-                                                        TL_OPTION_UPDATING))
+                                                        TL_OPTION_UPDATING,
+                                                        TL_WRITE_ALLOW_READ))
               MYSQL_YYABORT;
           }
         | DROP DATABASE if_exists ident