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c8fc3db1b0
CAN LEAD TO MISSING TABLES Overview -------- If the FOREIGN_KEY_CHECKS system variable is set to 0, it is possible to break a foreign key constraint by changing the type or character set of the foreign key column, or by dropping the foreign key index (without carrying out corresponding changes on another table in the relationship). If we subsequently set FOREIGN_KEY_CHECKS to 1 and execute ALTER TABLE involving the COPY algorithm on such a table, the following happens: 1) If ALTER TABLE does not contain a RENAME clause, the attempt to install the new version of the table instead of the old one will fail due to the fact that the inconsistency will be detected. An attempt to revert the partially executed alter table operation by restoring the old table definition will fail as well due to FOREIGN_KEY_CHECKS == 1. As a result, the table being altered will be lost. 2) If ALTER TABLE contains the RENAME clause, the inconsistency will not be detected (most probably due to other bugs). But if an attempt to install the new version of the table fails (for example, due to a failure when updating triggers associated with the table), reverting the partially executed alter table by restoring the old table definition will fail too. So the table being altered might be lost as well. Suggested fix ------------- The suggested fix is to temporarily unset the option bit representing FOREIGN_KEY_CHECKS when the old table definition is restored while reverting the partially executed operation.
365 lines
11 KiB
C++
365 lines
11 KiB
C++
/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/*
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Atomic rename of table; RENAME TABLE t1 to t2, tmp to t1 [,...]
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*/
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#include "sql_priv.h"
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#include "unireg.h"
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#include "sql_rename.h"
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#include "sql_cache.h" // query_cache_*
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#include "sql_table.h" // build_table_filename
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#include "sql_view.h" // mysql_frm_type, mysql_rename_view
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#include "sql_trigger.h"
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#include "lock.h" // MYSQL_OPEN_SKIP_TEMPORARY
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#include "sql_base.h" // tdc_remove_table, lock_table_names,
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#include "sql_handler.h" // mysql_ha_rm_tables
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#include "datadict.h"
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static TABLE_LIST *rename_tables(THD *thd, TABLE_LIST *table_list,
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bool skip_error);
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static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list);
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/*
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Every second entry in the table_list is the original name and every
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second entry is the new name.
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*/
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bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)
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{
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bool error= 1;
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bool binlog_error= 0;
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TABLE_LIST *ren_table= 0;
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int to_table;
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char *rename_log_table[2]= {NULL, NULL};
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DBUG_ENTER("mysql_rename_tables");
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/*
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Avoid problems with a rename on a table that we have locked or
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if the user is trying to to do this in a transcation context
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*/
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if (thd->locked_tables_mode || thd->in_active_multi_stmt_transaction())
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{
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my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
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ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
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DBUG_RETURN(1);
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}
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mysql_ha_rm_tables(thd, table_list);
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if (logger.is_log_table_enabled(QUERY_LOG_GENERAL) ||
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logger.is_log_table_enabled(QUERY_LOG_SLOW))
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{
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/*
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Rules for rename of a log table:
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IF 1. Log tables are enabled
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AND 2. Rename operates on the log table and nothing is being
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renamed to the log table.
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DO 3. Throw an error message.
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ELSE 4. Perform rename.
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*/
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for (to_table= 0, ren_table= table_list; ren_table;
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to_table= 1 - to_table, ren_table= ren_table->next_local)
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{
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int log_table_rename= 0;
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if ((log_table_rename=
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check_if_log_table(ren_table->db_length, ren_table->db,
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ren_table->table_name_length,
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ren_table->table_name, 1)))
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{
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/*
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as we use log_table_rename as an array index, we need it to start
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with 0, while QUERY_LOG_SLOW == 1 and QUERY_LOG_GENERAL == 2.
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So, we shift the value to start with 0;
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*/
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log_table_rename--;
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if (rename_log_table[log_table_rename])
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{
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if (to_table)
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rename_log_table[log_table_rename]= NULL;
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else
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{
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/*
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Two renames of "log_table TO" w/o rename "TO log_table" in
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between.
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*/
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my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
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ren_table->table_name);
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goto err;
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}
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}
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else
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{
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if (to_table)
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{
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/*
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Attempt to rename a table TO log_table w/o renaming
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log_table TO some table.
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*/
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my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), ren_table->table_name,
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ren_table->table_name);
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goto err;
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}
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else
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{
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/* save the name of the log table to report an error */
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rename_log_table[log_table_rename]= ren_table->table_name;
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}
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}
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}
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}
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if (rename_log_table[0] || rename_log_table[1])
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{
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if (rename_log_table[0])
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my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[0],
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rename_log_table[0]);
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else
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my_error(ER_CANT_RENAME_LOG_TABLE, MYF(0), rename_log_table[1],
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rename_log_table[1]);
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goto err;
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}
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}
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if (lock_table_names(thd, table_list, 0, thd->variables.lock_wait_timeout,
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MYSQL_OPEN_SKIP_TEMPORARY))
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goto err;
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for (ren_table= table_list; ren_table; ren_table= ren_table->next_local)
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tdc_remove_table(thd, TDC_RT_REMOVE_ALL, ren_table->db,
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ren_table->table_name, FALSE);
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error=0;
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/*
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An exclusive lock on table names is satisfactory to ensure
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no other thread accesses this table.
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*/
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if ((ren_table=rename_tables(thd,table_list,0)))
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{
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/* Rename didn't succeed; rename back the tables in reverse order */
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TABLE_LIST *table;
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/* Reverse the table list */
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table_list= reverse_table_list(table_list);
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/* Find the last renamed table */
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for (table= table_list;
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table->next_local != ren_table ;
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table= table->next_local->next_local) ;
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table= table->next_local->next_local; // Skip error table
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/* Revert to old names */
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rename_tables(thd, table, 1);
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/* Revert the table list (for prepared statements) */
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table_list= reverse_table_list(table_list);
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error= 1;
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}
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if (!silent && !error)
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{
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binlog_error= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
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if (!binlog_error)
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my_ok(thd);
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}
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if (!error)
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query_cache_invalidate3(thd, table_list, 0);
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err:
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DBUG_RETURN(error || binlog_error);
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}
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/*
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reverse table list
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SYNOPSIS
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reverse_table_list()
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table_list pointer to table _list
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RETURN
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pointer to new (reversed) list
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*/
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static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list)
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{
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TABLE_LIST *prev= 0;
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while (table_list)
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{
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TABLE_LIST *next= table_list->next_local;
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table_list->next_local= prev;
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prev= table_list;
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table_list= next;
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}
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return (prev);
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}
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/*
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Rename a single table or a view
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SYNPOSIS
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do_rename()
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thd Thread handle
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ren_table A table/view to be renamed
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new_db The database to which the table to be moved to
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new_table_name The new table/view name
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new_table_alias The new table/view alias
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skip_error Whether to skip error
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DESCRIPTION
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Rename a single table or a view.
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RETURN
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false Ok
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true rename failed
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*/
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bool
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do_rename(THD *thd, TABLE_LIST *ren_table, char *new_db, char *new_table_name,
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char *new_table_alias, bool skip_error)
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{
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int rc= 1;
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char name[FN_REFLEN + 1];
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const char *new_alias, *old_alias;
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frm_type_enum frm_type;
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enum legacy_db_type table_type;
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DBUG_ENTER("do_rename");
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if (lower_case_table_names == 2)
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{
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old_alias= ren_table->alias;
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new_alias= new_table_alias;
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}
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else
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{
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old_alias= ren_table->table_name;
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new_alias= new_table_name;
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}
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DBUG_ASSERT(new_alias);
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build_table_filename(name, sizeof(name) - 1,
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new_db, new_alias, reg_ext, 0);
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if (!access(name,F_OK))
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{
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my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_alias);
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DBUG_RETURN(1); // This can't be skipped
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}
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build_table_filename(name, sizeof(name) - 1,
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ren_table->db, old_alias, reg_ext, 0);
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frm_type= dd_frm_type(thd, name, &table_type);
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switch (frm_type)
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{
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case FRMTYPE_TABLE:
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{
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if (!(rc= mysql_rename_table(ha_resolve_by_legacy_type(thd,
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table_type),
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ren_table->db, old_alias,
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new_db, new_alias, 0)))
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{
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if ((rc= Table_triggers_list::change_table_name(thd, ren_table->db,
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old_alias,
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ren_table->table_name,
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new_db,
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new_alias)))
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{
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/*
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We've succeeded in renaming table's .frm and in updating
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corresponding handler data, but have failed to update table's
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triggers appropriately. So let us revert operations on .frm
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and handler's data and report about failure to rename table.
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*/
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(void) mysql_rename_table(ha_resolve_by_legacy_type(thd,
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table_type),
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new_db, new_alias,
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ren_table->db, old_alias, NO_FK_CHECKS);
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}
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}
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}
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break;
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case FRMTYPE_VIEW:
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/*
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change of schema is not allowed
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except of ALTER ...UPGRADE DATA DIRECTORY NAME command
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because a view has valid internal db&table names in this case.
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*/
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if (thd->lex->sql_command != SQLCOM_ALTER_DB_UPGRADE &&
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strcmp(ren_table->db, new_db))
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my_error(ER_FORBID_SCHEMA_CHANGE, MYF(0), ren_table->db,
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new_db);
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else
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rc= mysql_rename_view(thd, new_db, new_alias, ren_table);
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break;
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default:
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DBUG_ASSERT(0); // should never happen
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case FRMTYPE_ERROR:
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my_error(ER_FILE_NOT_FOUND, MYF(0), name, my_errno);
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break;
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}
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if (rc && !skip_error)
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DBUG_RETURN(1);
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DBUG_RETURN(0);
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}
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/*
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Rename all tables in list; Return pointer to wrong entry if something goes
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wrong. Note that the table_list may be empty!
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*/
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/*
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Rename tables/views in the list
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SYNPOSIS
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rename_tables()
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thd Thread handle
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table_list List of tables to rename
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skip_error Whether to skip errors
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DESCRIPTION
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Take a table/view name from and odd list element and rename it to a
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the name taken from list element+1. Note that the table_list may be
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empty.
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RETURN
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false Ok
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true rename failed
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*/
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static TABLE_LIST *
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rename_tables(THD *thd, TABLE_LIST *table_list, bool skip_error)
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{
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TABLE_LIST *ren_table, *new_table;
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DBUG_ENTER("rename_tables");
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for (ren_table= table_list; ren_table; ren_table= new_table->next_local)
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{
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new_table= ren_table->next_local;
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if (do_rename(thd, ren_table, new_table->db, new_table->table_name,
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new_table->alias, skip_error))
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DBUG_RETURN(ren_table);
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}
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DBUG_RETURN(0);
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}
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