My debian-based is booting so slow after I installed MySQL and imported some databases on it. Looking for some statement, I found this one during boot:
mysql> show full processlist;
+----+------------------+-----------+------+---------+------+----------------+----------------------------------------------------------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------------------+-----------+------+---------+------+----------------+----------------------------------------------------------------------+
| 9 | debian-sys-maint | localhost | NULL | Query | 12 | Opening tables | select count(*) into #discard from `information_schema`.`PARTITIONS` |
| 10 | root | localhost | NULL | Query | 0 | NULL | show full processlist |
+----+------------------+-----------+------+---------+------+----------------+----------------------------------------------------------------------+
2 rows in set (0.00 sec)
Here the statement that causing trouble:
select count(*) into #discard from `information_schema`.`PARTITIONS`
I have +-10 databases totaling over 8gb of data.
Is there any configuration to disable this query on system booting ? If yes, why run it during boot ?
Information
I have a standard MySQL installation without custom configs.
Best regards.
It seems Debian, whose Linux Mint is based upon, have scripts that get executed when the mysql server is started or restarted, to check for corrupted tables and make an alert for that.
In my Debian server, the culprit seems to be /etc/mysql/debian-start bash script, which in turn calls /usr/share/mysql/debian-start.inc.sh , so check both scripts and comment out the function that is iterating all your tables, from a quick look it seems the following:
check_for_crashed_tables;
which is called from the debian-start script I mentioned above.
Related
I'm using Ubuntu 16.04.3 and mysql Ver 14.14 Distrib 5.7.22.
When I try to alter my db table column with the following command the database appears to freeze;
mysql> alter table records modify column name varchar(150);
Table size is 2.8MiB (6,000 records).
I'm simply trying to change the varchar(150) part.
I have tried to do the same thing in GUI programs such as HeidiSQL and Workbench, same result - program crashes and I have to restart the session.
I am logged into the db and server as root. I checked the /var/log/mysql/error.log but it only displays failed login attempts, nothing relevant to this error.
Any ideas what's going on or how I can troubleshoot this?
Do you have any apps running long-running transactions against this table? If there are any transactions holding a metadata lock, it won't be able to start the ALTER TABLE.
If you can run SHOW PROCESSLIST in another window while the ALTER TABLE appears to hang, it might show "waiting for metadata lock".
+----+------+-----------+------+---------+------+---------------------------------+------------------------+-----------+---------------+
| Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined |
+----+------+-----------+------+---------+------+---------------------------------+------------------------+-----------+---------------+
| 4 | root | localhost | test | Query | 0 | init | show processlist | 0 | 0 |
| 5 | root | localhost | test | Query | 15 | Waiting for table metadata lock | alter table foo... | 0 | 0 |
+----+------+-----------+------+---------+------+---------------------------------+------------------------+-----------+---------------+
Then you need to figure out which app has an open transaction that is blocking the ALTER TABLE, and get that app to finish its transaction, or else kill the transaction.
We have problem to run php script via crontab. There are around 70 lines that run scripts installed in different virtual servers. When few lines are executed everything is working but when we have more some of them are not executed.
First we thought that this is crontab issue, but then we figure out that we are getting error from the script 'Error msg: Unable to connect to the database'. Just to let you now this script allow applications, that we have installed on our VPS to execut of the system's scheduled sending script (so you we can schedule our emails to be sent at a later date) on our server.
By getting this error we know that problem exist in the mysql engine. We are not mysql experts so maybe someone knows what to do with this. Here are few outputs from our mysql.
Uptime: 80832 Threads: 60 Questions: 4116373
Slow queries: 2067 Opens: 69721 Flush tables: 2
Open tables: 400 Queries per second avg: 50.925
and
+--------------------------+--------+
| Variable_name | Value |
+--------------------------+--------+
| Aborted_connects | 64 |
| Connections | 671995 |
| Max_used_connections | 215 |
| Ssl_client_connects | 0 |
| Ssl_connect_renegotiates | 0 |
| Ssl_finished_connects | 0 |
| Threads_connected | 60 |
+--------------------------+--------+
Do you see something suspicious here? Connections are opened only on localhost. In /etc/my.cnf there is a setup
bind-address = 127.0.0.1
I am writing a small web app in Go, which uses mysql to store data.
I got intermittent mysql error if the web sever didn't get any request after some amount of time(> 8 hours):
[mysql] 2017/02/08 16:31:56 packets.go:33: unexpected EOF
[mysql] 2017/02/08 16:31:56 packets.go:130: write tcp 127.0.0.1:49188->127.0.0.1:3306: write: broken pipe
I found some related discussion on github(issue 529, issue 257 and issue 446). From what I understand, mysql db would close the connection if timeout is reached.
I tried to set SetMaxOpenConns to 9 and SetMaxIdleConns to 0 as some people recommended. However, this threw exception immediately. (But if I set SetMaxIdleConns larger than 0, there was no immediate exception thrown)
I also tried to set SetConnMaxLifetime to 5 mins. This threw exception too after 5 mins.
Now I am trying the code below:
db.SetConnMaxLifetime(0)
db.SetMaxOpenConns(10)
db.SetMaxIdleConns(5)
It has been running for 20 mins. It's still too early to tell.
(UPDATE: this doesn't work either)
Here is configuration:
driver: go-sql-driver V1.3.
go version: go1.7.1 darwin/amd64
mysql: latest from docker hub
rkt version: 1.18
CoreOS: 1284.0.0
Perhaps you can start a heartbeat Goroutine to avoid timeout.
you can check your mysql time_wait variable:
mysql> show global variables like 'wait_timeout':
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wait_timeout | 300 |
+---------------+-------+
1 row in set (0.00 sec)
then use db.SetConnMaxLifetime(120*time.Second), which mean when db connection is idle over than 120s, sql.db will reopen or get a new connection from db pool by db.Open. If you not set connection max life time, you maybe use a closed connection and got the error.
watching the mysql process list，mysql> show processlist;，if connection sleep over than 300s，it's recycled by mysql:
mysql> show processlist;
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
| 4 | event_scheduler | localhost | NULL | Daemon | 1363480 | Waiting on empty queue | NULL |
| 26539 | root | 172.17.0.1:48732 | NULL | Query | 0 | starting | show processlist |
| 26575 | auditcenter | 172.17.0.1:51714 | obs_gb_test | Sleep | 51 | | NULL |
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
3 rows in set (0.00 sec)
SetMaxOpenConns and SetMaxIdleConns is used for setting connection resource, see enter link description here
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
I have a thread showing in PHPmyadmin under processes. However, when I click kill, I get the error:
phpMyAdmin was unable to kill thread 148. It probably has already been closed.
Why does this thread still then show as active? How can I remove it entirely?
Open mysql client and type
mysql> show processlist;
+-----+------+-----------+------+---------+------+-------+------------------+-----------+---------------+-----------+
| Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined | Rows_read |
+-----+------+-----------+------+---------+------+-------+------------------+-----------+---------------+-----------+
| 106 | root | localhost | NULL | Query | 0 | NULL | show processlist | 0 | 0 | 0 |
+-----+------+-----------+------+---------+------+-------+------------------+-----------+---------------+-----------+
1 row in set (0.00 sec)
you'll see processes with ID, than you can do this:
mysql> kill 106;
and your process (id = 106) will be killed.
Between the time that phpMyAdmin received the list of processes and the time you clicked to kill one of them, this process had finished by itself.
See also https://sourceforge.net/p/phpmyadmin/feature-requests/1490/.
This phenomenon is caused by the connection used to access PHPmyadmin itself, hence it doesn't show on the direct MySQLQuery. It can't be killed, as it would close the PHPmyadmin connection.