I was working with netbean's database explorer (services tab) and accidentally deleted one of the databases.
I was trying to connect to a database and there were 2 options in the context menu for connecting.
1)Connect
2)Delete
I accidentally hit delete. It did not even ask me for confirmation. Is there anyway to recover the database?
I don't have access to mysql server. I can just connect to the database using mysql workbench.
Thanks a ton!
If you have the binary logging enabled, then you might have a chance to use it to restore your database.
Else use an older backup and restore it !
To find binary logs status :
mysql> show variables like '%bin%';
+---------------------------------+----------------------+
| Variable_name | Value |
+---------------------------------+----------------------+
| binlog_cache_size | 32768 |
| innodb_locks_unsafe_for_binlog | OFF |
| log_bin | OFF |
| log_bin_trust_function_creators | OFF |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| sync_binlog | 0 |
+---------------------------------+----------------------+
7 rows in set (0.00 sec)
Related
I need to download locally (macOS BigSur) a large dataset (millions of rows) from an AWS RDS database (MySQL 5.7).
Thanks to this great post I am able to connect and download on my machine some data into a csv file:
mysql --host=$HOST --user $USER --password=$PASSWORD --database=$DATABASE --port=$PORT --batch \
--quick -e "$QUERY" \
| sed $'s/\\t/","/g;s/^/"/;s/$/"/;s/\\n//g' > $FILE_PATH
However, if I extend my query to thousands of records, after few seconds the process stops and the csv ends up truncated (literally the last written row is truncated half way), so I assume there is some kind of stream or timeout or buffer issue.
mysql> SHOW VARIABLES LIKE '%timeout';
+-----------------------------+----------+
| Variable_name | Value |
+-----------------------------+----------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| have_statement_timeout | YES |
| innodb_flush_log_at_timeout | 1 |
| innodb_lock_wait_timeout | 50 |
| innodb_rollback_on_timeout | OFF |
| interactive_timeout | 28800 |
| lock_wait_timeout | 31536000 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| rpl_stop_slave_timeout | 31536000 |
| slave_net_timeout | 60 |
| wait_timeout | 28800 |
+-----------------------------+----------+
Since the command does stops after ~10sec I assume it depends on the connect_timeout value. However I tried setting it with SET ##GLOBAL.connect_timeout=7200 but I get a permission error. I tried adding the --connect-timeout=7200 parameter on the command, but it does not work (which strikes me the most).
Running the query (limited to ~250k rows) on my client (SequelAce) it runs fine, so I can exclude issues with the data or the the SQL script itself.
Any ideas or suggestions?
Are there better tools for the job maybe?
I have various Google Cloud functions which are writing and reading to a Cloud SQL database (MySQL). The processes work however when the functions happen to run at the same time I am getting a Broken pipe error. I am using SQLAlchemy with Python, MySQL and the processes are cloud functions and the db is a google cloud database.I have seen suggested solutions that involve setting timeout values to longer. I was wondering if this would be a good approach or if there is a better approach? Thanks for your help in advance.
Heres the SQL broken pipe error:
(pymysql.err.OperationalError) (2006, "MySQL server has gone away (BrokenPipeError(32, 'Broken pipe'))")
(Background on this error at: http://sqlalche.me/e/13/e3q8)
Here are the MySQL timeout values:
show variables like '%timeout%';
+-------------------------------------------+----------+
| Variable_name | Value |
+-------------------------------------------+----------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| have_statement_timeout | YES |
| innodb_flush_log_at_timeout | 1 |
| innodb_lock_wait_timeout | 50 |
| innodb_rollback_on_timeout | OFF |
| interactive_timeout | 28800 |
| lock_wait_timeout | 31536000 |
| net_read_timeout | 30 |
| net_write_timeout | 60 |
| rpl_semi_sync_master_async_notify_timeout | 5000000 |
| rpl_semi_sync_master_timeout | 3000 |
| rpl_stop_slave_timeout | 31536000 |
| slave_net_timeout | 30 |
| wait_timeout | 28800 |
+-------------------------------------------+----------+
15 rows in set (0.01 sec)
If you cache your connection, for performance, it's normal to lost the connection after a while. To prevent this, you have to deal with disconnection.
In addition, because you are working with Cloud Functions, only one request can be handle in the same time on one instance (if you have 2 concurrent requests, you will have 2 instances). Thus, set your pool size to 1 to save resource on your database side (in case of huge parallelization)
Following documentation on how to set up a MariaDB Galera cluster, I simply created the proper config files and started my primary db server with the galera_new_cluster command (I'm running RHEL7). According to the documentation, at that point you should be able to run:
SHOW STATUS LIKE 'wsrep_cluster_size';
And see
+--------------------+-------+
| Variable_name | Value |
+--------------------+-------+
| wsrep_cluster_size | 1 |
+--------------------+-------+
However, I see wsrep_cluster_size of zero with these other relevant values:
MariaDB [(none)]> show global status like 'wsrep%';
+--------------------------+----------------------+
| Variable_name | Value |
+--------------------------+----------------------+
| wsrep_cluster_conf_id | 18446744073709551615 |
| wsrep_cluster_size | 0 |
| wsrep_cluster_state_uuid | |
| wsrep_cluster_status | Disconnected |
| wsrep_connected | OFF |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_index | 18446744073709551615 |
| wsrep_provider_name | |
| wsrep_provider_vendor | |
| wsrep_provider_version | |
| wsrep_ready | OFF |
| wsrep_thread_count | 0 |
+--------------------------+----------------------+
My settings in /etc/my.cnf.d/server.cnf are:
bind_address=172.28.7.15
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_name="galera_cluster"
wsrep_cluster_address="gcomm://172.28.7.15,172.28.7.18,172.28.7.19"
wsrep_node_address=172.28.7.15
wsrep_node_name='node01'
wsrep_slave_threads=1
wsrep_certify_nonPK=1
wsrep_max_ws_rows=131072
wsrep_max_ws_size=1073741824
wsrep_debug=1
wsrep_convert_LOCK_to_trx=0
wsrep_retry_autocommit=1
wsrep_auto_increment_control=1
wsrep_drupal_282555_workaround=0
wsrep_causal_reads=0
wsrep_notify_cmd=
wsrep_sst_method=rsync
And I've confirmed that the variables are loaded using SHOW VARIABLES.
I feel like I'm following the documentation exactly and it's just not showing what I expect. The only warnings in logs are warnings about SSL not being set up - is that required?
You mentioned you didn't see any WSREP logs in /var/log/mariadb/mariadb.log. Perhaps wsrep_on option is set to OFF. Try setting it to ON.
Lots of documentation assumes MariaDB Galera 10.0. But in 10.1 and higher, wsrep_on defaults to OFF.
Default Value: OFF (>= MariaDB 10.1), ON (<= MariaDB Galera Cluster 10.0)
https://mariadb.com/kb/en/mariadb/galera-cluster-system-variables/#wsrep_on
For Centos 7, edit your /etc/my.cnf file and
setenforce 0
write it on your all nodes.
Then start your cluster and connect nodes.
I searched a lot on the internet but not found any brief explanation on mysql timeouts with examples. I want to know the meaning of mysql diffenernt timeouts as listed below and also want to know why and when we use them.
+----------------------------+----------+
| Variable_name | Value |
+----------------------------+----------+
| connect_timeout | 10 |
| delayed_insert_timeout | 300 |
| innodb_lock_wait_timeout | 50 |
| interactive_timeout | 28800 |
| net_read_timeout | 3 |
| net_write_timeout | 60 |
| slave_net_timeout | 3600 |
| wait_timeout | 28800 |
+----------------------------+----------+
Also in ruby on rails application i can set read_timeout in my database.yml file. if query is not able to read the data within specified read_timeout value mysql will close the connection. so i also want to know what is the differentce between net_read_timeout and read_timeout
Thanks,
From The Ultimate Guide to Ruby Timeouts
connect (or open) - time to open the connection
read (or receive) - time to receive data after connected
write (or send) - time to send data after connected
checkout - time to checkout a connection from the pool
statement - time to execute a database statement
With administrative permissions im mysql, how can I see all the open connections to a specific db in my server?
The command is
SHOW PROCESSLIST
Unfortunately, it has no narrowing parameters. If you need them you can do it from the command line:
mysqladmin processlist | grep database-name
As well you can use:
mysql> show status like '%onn%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| Aborted_connects | 0 |
| Connections | 303 |
| Max_used_connections | 127 |
| Ssl_client_connects | 0 |
| Ssl_connect_renegotiates | 0 |
| Ssl_finished_connects | 0 |
| Threads_connected | 127 |
+--------------------------+-------+
7 rows in set (0.01 sec)
Feel free to use
Mysql-server-status-variables or Too-many-connections-problem
That should do the trick for the newest MySQL versions:
SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST WHERE DB like "%DBName%";
You can invoke MySQL show status command
show status like 'Conn%';
For more info read Show open database connections
SQL:
show full processlist;
This is what the MySQL Workbench does.
In MySql,the following query shall show the total number of open connections:
show status like 'Threads_connected';
If you're running a *nix system, also consider mytop.
To limit the results to one database, press "d" when it's running then type in the database name.
From the monitoring context here is how you can easily view the connections to all databases sorted by database. With that data easily monitor.
SELECT DB,USER,HOST,STATE FROM INFORMATION_SCHEMA.PROCESSLIST ORDER BY DB DESC;
+------+-------+---------------------+-----------+
| DB | USER | HOST | STATE |
+------+-------+---------------------+-----------+
| web | tommy | 201.29.120.10:41146 | executing |
+------+-------+---------------------+-----------+
If we encounter any hosts hots max connections and then not able to connect, then we can reset host tables by flushing it and is as follows:
FLUSH HOSTS;
In query browser right click on database and select processlist