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Commit daafaa0f authored by Venkata Sidagam's avatar Venkata Sidagam
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Bug #11754178 45740: MYSQLDUMP DOESN'T DUMP GENERAL_LOG AND SLOW_QUERY 

                     CAUSES RESTORE PROBLEM
Problem Statement:
------------------
mysqldump is not having the dump stmts for general_log and slow_log
tables. That is because of the fix for Bug#26121. Hence, after 
dropping the mysql database, and applying the dump by enabling the 
logging, "'general_log' table not found" errors are logged into the 
server log file.

Analysis:
---------
As part of the fix for Bug#26121, we skipped the dumping of tables 
for general_log and slow_log, because the data dump of those tables 
are taking LOCKS, which is not allowed for log tables.

Fix:
----
We came up with an approach that instead of taking both meta data 
and data dump information for those tables, take only the meta data 
dump which doesn't need LOCKS.
As part of fixing the issue we came up with below algorithm.
Design before fix:
1) mysql database is having tables like db, event,... general_log,
   ... slow_log...
2) Skip general_log and slow_log while preparing the tables list
3) Take the TL_READ lock on tables which are present in the table 
   list and do 'show create table'.
4) Release the lock.

Design with the fix:
1) mysql database is having tables like db, event,... general_log,
   ... slow_log...
2) Skip general_log and slow_log while preparing the tables list
3) Explicitly call the 'show create table' for general_log and 
   slow_log
3) Take the TL_READ lock on tables which are present in the table 
   list and do 'show create table'.
4) Release the lock.

While taking the meta data dump for general_log and slow_log the 
"CREATE TABLE" is replaced with "CREATE TABLE IF NOT EXISTS". 
This is because we skipped "DROP TABLE" for those tables, 
"DROP TABLE" fails for these tables if logging is enabled. 
Customer is applying the dump by enabling logging so, if the dump 
has "DROP TABLE" it will fail. Hence, removed the "DROP TABLE" 
stmts for those tables.
  
After the fix we could observe "Table 'mysql.general_log' 
doesn't exist" errors initially that is because in the customer 
scenario they are dropping the mysql database by enabling the 
logging, Hence, those errors are expected. Once we apply the 
dump which is taken before the "drop database mysql", the errors 
will not be there.

client/mysqldump.c:
  In get_table_structure() added code to skip the DROP TABLE stmts for general_log
  and slow_log tables, because when logging is enabled those stmts will fail. And
  replaced CREATE TABLE with CREATE IF NOT EXISTS for those tables, just to make 
  sure CREATE stmt for those tables doesn't fail since we removed DROP stmts for
  those tables.
  In dump_all_tables_in_db() added code to call get_table_structure() for 
  general_log and slow_log tables.
mysql-test/r/mysqldump.result:
  Added a test as part of fix for Bug #11754178
mysql-test/t/mysqldump.test:
  Added a test as part of fix for Bug #11754178
parent fe3f7993
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Inline Side-by-side
Showing with 118 additions and 11 deletions
client/mysqldump.c
View file @ daafaa0f
......@@ -84,6 +84,15 @@
#define IGNORE_DATA 0x01 /* don't dump data for this table */
#define IGNORE_INSERT_DELAYED 0x02 /* table doesn't support INSERT DELAYED */
/* general_log or slow_log tables under mysql database */
static inline my_bool general_log_or_slow_log_tables(const char *db,
const char *table)
{
return (strcmp(db, "mysql") == 0) &&
((strcmp(table, "general_log") == 0) ||
(strcmp(table, "slow_log") == 0));
}
static void add_load_option(DYNAMIC_STRING *str, const char *option,
const char *option_value);
static ulong find_set(TYPELIB *lib, const char *x, uint length,
......@@ -2458,6 +2467,7 @@ static uint get_table_structure(char *table, char *db, char *table_type,
"TABLE_SCHEMA = '%s' AND TABLE_NAME = '%s'";
FILE *sql_file= md_result_file;
int len;
my_bool is_log_table;
MYSQL_RES *result;
MYSQL_ROW row;
DBUG_ENTER("get_table_structure");
......@@ -2542,9 +2552,12 @@ static uint get_table_structure(char *table, char *db, char *table_type,
/*
Even if the "table" is a view, we do a DROP TABLE here. The
view-specific code below fills in the DROP VIEW.
We will skip the DROP TABLE for general_log and slow_log, since
those stmts will fail, in case we apply dump by enabling logging.
*/
fprintf(sql_file, "DROP TABLE IF EXISTS %s;\n",
opt_quoted_table);
if (!general_log_or_slow_log_tables(db, table))
fprintf(sql_file, "DROP TABLE IF EXISTS %s;\n",
opt_quoted_table);
check_io(sql_file);
}
......@@ -2656,12 +2669,25 @@ static uint get_table_structure(char *table, char *db, char *table_type,
row= mysql_fetch_row(result);
fprintf(sql_file, (opt_compatible_mode & 3) ? "%s;\n" :
"/*!40101 SET @saved_cs_client = @@character_set_client */;\n"
"/*!40101 SET character_set_client = utf8 */;\n"
"%s;\n"
"/*!40101 SET character_set_client = @saved_cs_client */;\n",
row[1]);
is_log_table= general_log_or_slow_log_tables(db, table);
if (is_log_table)
row[1]+= 13; /* strlen("CREATE TABLE ")= 13 */
if (opt_compatible_mode & 3)
{
fprintf(sql_file,
is_log_table ? "CREATE TABLE IF NOT EXISTS %s;\n" : "%s;\n",
row[1]);
}
else
{
fprintf(sql_file,
"/*!40101 SET @saved_cs_client = @@character_set_client */;\n"
"/*!40101 SET character_set_client = utf8 */;\n"
"%s%s;\n"
"/*!40101 SET character_set_client = @saved_cs_client */;\n",
is_log_table ? "CREATE TABLE IF NOT EXISTS " : "",
row[1]);
}
check_io(sql_file);
mysql_free_result(result);
......@@ -4261,6 +4287,22 @@ static int dump_all_tables_in_db(char *database)
if (opt_xml)
print_xml_tag(md_result_file, "", "\n", "database", "name=", database, NullS);
if (strcmp(database, "mysql") == 0)
{
char table_type[NAME_LEN];
char ignore_flag;
uint num_fields;
num_fields= get_table_structure((char *) "general_log",
database, table_type, &ignore_flag);
if (num_fields == 0)
verbose_msg("-- Warning: get_table_structure() failed with some internal "
"error for 'general_log' table\n");
num_fields= get_table_structure((char *) "slow_log",
database, table_type, &ignore_flag);
if (num_fields == 0)
verbose_msg("-- Warning: get_table_structure() failed with some internal "
"error for 'slow_log' table\n");
}
if (lock_tables)
{
DYNAMIC_STRING query;
......
mysql-test/r/mysqldump.result
View file @ daafaa0f
......@@ -5067,5 +5067,47 @@ RETURN CONCAT(']]]]><![CDATA[>, ', s, '!')
DROP DATABASE BUG52792;
USE test;
#
# Bug#45740 MYSQLDUMP DOESN'T DUMP GENERAL_LOG AND SLOW_QUERY CAUSES RESTORE PROBLEM
#
SET @old_log_output_state= @@global.log_output;
SET @old_general_log_state= @@global.general_log;
SET @old_slow_query_log_state= @@global.slow_query_log;
call mtr.add_suppression("Failed to write to mysql.general_log");
SET @@global.log_output="TABLE";
SET @@global.general_log='ON';
SET @@global.slow_query_log='ON';
DROP DATABASE mysql;
Warnings:
Error 1146 Table 'mysql.proc' doesn't exist
Error 1146 Table 'mysql.event' doesn't exist
SHOW CREATE TABLE mysql.general_log;
Table Create Table
general_log CREATE TABLE `general_log` (
`event_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`user_host` mediumtext NOT NULL,
`thread_id` int(11) NOT NULL,
`server_id` int(10) unsigned NOT NULL,
`command_type` varchar(64) NOT NULL,
`argument` mediumtext NOT NULL
) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='General log'
SHOW CREATE TABLE mysql.slow_log;
Table Create Table
slow_log CREATE TABLE `slow_log` (
`start_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`user_host` mediumtext NOT NULL,
`query_time` time NOT NULL,
`lock_time` time NOT NULL,
`rows_sent` int(11) NOT NULL,
`rows_examined` int(11) NOT NULL,
`db` varchar(512) NOT NULL,
`last_insert_id` int(11) NOT NULL,
`insert_id` int(11) NOT NULL,
`server_id` int(10) unsigned NOT NULL,
`sql_text` mediumtext NOT NULL
) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='Slow log'
SET @@global.log_output= @old_log_output_state;
SET @@global.slow_query_log= @old_slow_query_log_state;
SET @@global.general_log= @old_general_log_state;
#
# End of 5.1 tests
#
mysql-test/t/mysqldump.test
View file @ daafaa0f
......@@ -2308,9 +2308,32 @@ DROP DATABASE BUG52792;
USE test;
# Wait till we reached the initial number of concurrent sessions
--source include/wait_until_count_sessions.inc
--echo #
--echo # End of 5.1 tests
--echo # Bug#45740 MYSQLDUMP DOESN'T DUMP GENERAL_LOG AND SLOW_QUERY CAUSES RESTORE PROBLEM
--echo #
SET @old_log_output_state= @@global.log_output;
SET @old_general_log_state= @@global.general_log;
SET @old_slow_query_log_state= @@global.slow_query_log;
# Wait till we reached the initial number of concurrent sessions
--source include/wait_until_count_sessions.inc
call mtr.add_suppression("Failed to write to mysql.general_log");
--exec $MYSQL_DUMP -uroot --all-databases > $MYSQLTEST_VARDIR/tmp/bug45740.sql
# Make log_output as table and enable general_log and slow_log
SET @@global.log_output="TABLE";
SET @@global.general_log='ON';
SET @@global.slow_query_log='ON';
DROP DATABASE mysql;
--exec $MYSQL < $MYSQLTEST_VARDIR/tmp/bug45740.sql
SHOW CREATE TABLE mysql.general_log;
SHOW CREATE TABLE mysql.slow_log;
--remove_file $MYSQLTEST_VARDIR/tmp/bug45740.sql
SET @@global.log_output= @old_log_output_state;
SET @@global.slow_query_log= @old_slow_query_log_state;
SET @@global.general_log= @old_general_log_state;
--echo #
--echo # End of 5.1 tests
--echo #
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