I'm trying to solve a performance issue I have on a Mysql database and to do that I'm using mysqltuner.
What I don't understand is why in phpmyadmin and mysqltuner I have several variable mentioned, whereas when I open the my.cnf file is almost empty. There is the maxconnections parameter only.
Where are stored the other variables ???
Other variables are defaults.
My.cnf only override defaults.
You can look for defaults here: https://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html
Most of what mysqltuner comes from
SHOW GLOBAL VARIABLES;
SHOW GLOBAL STATUS;
my.cnf is merely the overrides to the default static VARIABLES built into the server. STATUS are counters, etc that change over time.
Note the word GLOBAL. Those are the defaults for the corresponding SESSION values that belong to your connection. The VARIABLES you change in phpmyadmin, will not be permanent. You have to edit my.cnf and restart mysqld to get permanent changes.
Usually you cannot tune your way out of a performance problem. Once you have the main cache size set (which engine are you using? how much ram do you have?), not much other tuning is worth doing.
The main performance gains are from improving the queries and/or the schema, such as adding composite indexes. Let's see a slow query, and we can discuss this further.
MysqlTuner is reading variables and status at the runtime.
i need to update listen_addresses in postgres.conf file and want to avoid restart of postgres server process. I tried pg_ctl reload but its not working. Postgres documentation for this parameter says "This parameter can only be set at server start."
http://www.postgresql.org/docs/8.4/static/runtime-config-connection.html#GUC-LISTEN-ADDRESSES
It there any possible way to avoid the restart?
It there any possible way to avoid the restart?
No. That's why the documentation says it may only be set at restart.
If you can't afford the downtime for a simple database restart then you almost certainly need to have a connection pooling and failover system in place anyway. Start planning that so you can introduce it at the same time.
Also, 8.4 is old. If you're restarting a busy system anyway, consider planning an upgrade into the mix. Look at pg_upgrade.
I got the Error Code: 2013. Lost connection to MySQL server during query error when I tried to add an index to a table using MySQL Workbench.
I noticed also that it appears whenever I run long query.
Is there away to increase the timeout value?
New versions of MySQL WorkBench have an option to change specific timeouts.
For me it was under Edit → Preferences → SQL Editor → DBMS connection read time out (in seconds): 600
Changed the value to 6000.
Also unchecked limit rows as putting a limit in every time I want to search the whole data set gets tiresome.
If your query has blob data, this issue can be fixed by applying a my.ini change as proposed in this answer:
[mysqld]
max_allowed_packet=16M
By default, this will be 1M (the allowed maximum value is 1024M). If the supplied value is not a multiple of 1024K, it will automatically be rounded to the nearest multiple of 1024K.
While the referenced thread is about the MySQL error 2006, setting the max_allowed_packet from 1M to 16M did fix the 2013 error that showed up for me when running a long query.
For WAMP users: you'll find the flag in the [wampmysqld] section.
Start the DB server with the comandline option net_read_timeout / wait_timeout and a suitable value (in seconds) - for example: --net_read_timeout=100.
For reference see here and here.
SET ##local.net_read_timeout=360;
Warning: The following will not work when you are applying it in remote connection:
SET ##global.net_read_timeout=360;
Edit: 360 is the number of seconds
Add the following into /etc/mysql/cnf file:
innodb_buffer_pool_size = 64M
example:
key_buffer = 16M
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
innodb_buffer_pool_size = 64M
In my case, setting the connection timeout interval to 6000 or something higher didn't work.
I just did what the workbench says I can do.
The maximum amount of time the query can take to return data from the DBMS.Set 0 to skip the read timeout.
On Mac
Preferences -> SQL Editor -> Go to MySQL Session -> set connection read timeout interval to 0.
And it works 😄
There are three likely causes for this error message
Usually it indicates network connectivity trouble and you should check the condition of your network if this error occurs frequently
Sometimes the “during query” form happens when millions of rows are being sent as part of one or more queries.
More rarely, it can happen when the client is attempting the initial connection to the server
For more detail read >>
Cause 2 :
SET GLOBAL interactive_timeout=60;
from its default of 30 seconds to 60 seconds or longer
Cause 3 :
SET GLOBAL connect_timeout=60;
You should set the 'interactive_timeout' and 'wait_timeout' properties in the mysql config file to the values you need.
Just perform a MySQL upgrade that will re-build innoDB engine along with rebuilding of many tables required for proper functioning of MySQL such as performance_schema, information_schema, etc.
Issue the below command from your shell:
sudo mysql_upgrade -u root -p
If you experience this problem during the restore of a big dump-file and can rule out the problem that it has anything to do with network (e.g. execution on localhost) than my solution could be helpful.
My mysqldump held at least one INSERT that was too big for mysql to compute. You can view this variable by typing show variables like "net_buffer_length"; inside your mysql-cli.
You have three possibilities:
increase net_buffer_length inside mysql -> this would need a server restart
create dump with --skip-extended-insert, per insert one line is used -> although these dumps are much nicer to read this is not suitable for big dumps > 1GB because it tends to be very slow
create dump with extended inserts (which is the default) but limit the net-buffer_length e.g. with --net-buffer_length NR_OF_BYTES where NR_OF_BYTES is smaller than the server's net_buffer_length -> I think this is the best solution, although slower no server restart is needed.
I used following mysqldump command:
mysqldump --skip-comments --set-charset --default-character-set=utf8 --single-transaction --net-buffer_length 4096 DBX > dumpfile
On the basis of what I have understood this error was caused due to read timeout and max allowed packet default is 4M. if your query file more than 4Mb then you get an error. this worked for me
change the read timeout. For changing go to Workbench Edit → Preferences → SQL Editor
2. change the max_allowed_packet manually by editing the file my.ini. for editing go to "C:\ProgramData\MySQL\MySQL Server 8.0\my.ini". The folder ProgramData folder is hidden so if you did not see then select show hidden file in view settings. set the max_allowed_packet = 16M in my.ini file.
3. Restart MySQL. for restarting go to win+ R -> services.msc and restart MySQL.
I know its old but on mac
1. Control-click your connection and choose Connection Properties.
2. Under Advanced tab, set the Socket Timeout (sec) to a larger value.
Sometimes your SQL-Server gets into deadlocks, I've been in to this problem like 100 times. You can either restart your computer/laptop to restart server (easy way) OR you can go to task-manager>services>YOUR-SERVER-NAME(for me , it was MySQL785 something like this). And right-click > restart.
Try executing query again.
Try please to uncheck limit rows in in Edit → Preferences →SQL Queries
because You should set the 'interactive_timeout' and 'wait_timeout' properties in the mysql config file to the values you need.
Change "read time out" time in Edit->Preferences->SQL editor->MySQL session
I got the same issue when loading a .csv file.
Converted the file to .sql.
Using below command I manage to work around this issue.
mysql -u <user> -p -D <DB name> < file.sql
Hope this would help.
If all the other solutions here fail - check your syslog (/var/log/syslog or similar) to see if your server is running out of memory during the query.
Had this issue when innodb_buffer_pool_size was set too close to physical memory without a swapfile configured. MySQL recommends for a database specific server setting innodb_buffer_pool_size at a max of around 80% of physical memory, I had it set to around 90%, the kernel was killing the mysql process. Moved innodb_buffer_pool_size back down to around 80% and that fixed the issue.
Go to Workbench Edit → Preferences → SQL Editor → DBMS connections read time out : Up to 3000.
The error no longer occurred.
I faced this same issue. I believe it happens when you have foreign keys to larger tables (which takes time).
I tried to run the create table statement again without the foreign key declarations and found it worked.
Then after creating the table, I added the foreign key constrains using ALTER TABLE query.
Hope this will help someone.
This happened to me because my innodb_buffer_pool_size was set to be larger than the RAM size available on the server. Things were getting interrupted because of this and it issues this error. The fix is to update my.cnf with the correct setting for innodb_buffer_pool_size.
Go to:
Edit -> Preferences -> SQL Editor
In there you can see three fields in the "MySQL Session" group, where you can now set the new connection intervals (in seconds).
Turns out our firewall rule was blocking my connection to MYSQL. After the firewall policy is lifted to allow the connection i was able to import the schema successfully.
I had the same problem - but for me the solution was a DB user with too strict permissions.
I had to allow the Execute ability on the mysql table. After allowing that I had no dropping connections anymore
Check if the indexes are in place first.
SELECT *
FROM INFORMATION_SCHEMA.STATISTICS
WHERE TABLE_SCHEMA = '<schema>'
I ran into this while running a stored proc- which was creating lots of rows into a table in the database.
I could see the error come right after the time crossed the 30 sec boundary.
I tried all the suggestions in the other answers. I am sure some of it helped , however- what really made it work for me was switching to SequelPro from Workbench.
I am guessing it was some client side connection that I could not spot in Workbench.
Maybe this will help someone else as well ?
If you are using SQL Work Bench, you can try using Indexing, by adding an index to your tables, to add an index, click on the wrench(spanner) symbol on the table, it should open up the setup for the table, below, click on the index view, type an index name and set the type to index, In the index columns, select the primary column in your table.
Do the same step for other primary keys on other tables.
There seems to be an answer missing here for those using SSH to connect to their MySQL database. You need to check two places not 1 as suggested by other answers:
Workbench Edit → Preferences → SQL Editor → DBMS
Workbench Edit → Preferences → SSH → Timeouts
My default SSH Timeouts were set very low and causing some (but apparently not all) of my timeout issues. After, don't forget to restart MySQL Workbench!
Last, it may be worth contacting your DB Admin and asking them to increase wait_timeout & interactive_timeout properties in mysql itself via my.conf + mysql restart or doing a global set if restarting mysql is not an option.
Hope this helps!
Three things to be followed and make sure:
Whether multiple queries show lost connection?
how you use set query in MySQL?
how delete + update query simultaneously?
Answers:
Always try to remove definer as MySQL creates its own definer and if multiple tables involved for updation try to make a single query as sometimes multiple query shows lost connection
Always SET value at the top but after DELETE if its condition doesn't involve SET value.
Use DELETE FIRST THEN UPDATE IF BOTH OF THEM OPERATIONS ARE PERFORMED ON DIFFERENT TABLES
I had this error message due to a problem after of upgrade Mysql. The error appeared immediately after I tried to do any query
Check mysql error log files in path /var/log/mysql (linux)
In my case reassigning Mysql owner to the Mysql system folder worked for me
chown -R mysql:mysql /var/lib/mysql
Establish connection first
mysql --host=host.com --port=3306 -u username -p
then select your db use dbname
then source dumb source C:\dumpfile.sql.
After it's done \q
I need to set ft_min_word_len = 3.
I never restarted my mysql server on my production server. So I fear this moment :).
Are there any way to set ft_min_word_len = 3 without restarting mysql?
And if i must restart it, can you tell me the exact step I have to do?
I am on Devian GNU/Linux
MySQL: 5.0.32
(where I can find where is the mysql configuration file?)
Thanks a lot
No, I'm afraid you need to restart MySQL for it to accept the change. That said, there's nothing to be afraid of, as this won't affect any data. (If you're feeling paranoid, simply carry out the change/restart at an off-peak time, when site traffic is low.)
In terms of the configuration file, I think it lives in /etc/mysql/my.cnf on Debian. (If not, check /etc/my.cnf.)
To restart the service, simply issue a "/etc/init.d/mysql restart" command and all should be well.
This may be a dumb question, but is it possible to change the MySQL configuration options such as innodb_buffer_pool_size at runtime?
Or, equivalently, is there a way to reload MySQL without closing existing connections or refusing new connections (like you can do with Apache)?
Linux_32 (2.6.26) + MySQL 5.0.24a
According to this MySQL forum post, it is not possible to set innodb_buffer_pool_size at runtime.
So the question remains: is it possible to change the MySQL configuration and reload the daemon transparently to its users?
Yes, you can (depending on your server version).
The innodb_buffer_pool_size is a dynamic variable since 5.7.5 as this manual entry says.
Here is some further information about the server's behaviour when changing the size.