mirror of
https://github.com/MariaDB/server.git
synced 2025-01-17 20:42:30 +01:00
14aa2c020e
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. |
||
|---|---|---|
| .. | ||
| .cvsignore | ||
| client_priv.h | ||
| CMakeLists.txt | ||
| completion_hash.cc | ||
| completion_hash.h | ||
| echo.c | ||
| get_password.c | ||
| Makefile.am | ||
| my_readline.h | ||
| mysql.cc | ||
| mysql_upgrade.c | ||
| mysqladmin.cc | ||
| mysqlbinlog.cc | ||
| mysqlcheck.c | ||
| mysqldump.c | ||
| mysqlimport.c | ||
| mysqlshow.c | ||
| mysqlslap.c | ||
| mysqltest.cc | ||
| readline.cc | ||
| sql_string.cc | ||
| sql_string.h | ||