Questions tagged [mysql]

All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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2
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1answer
140 views

mysql 5.5 strange bug

I am trying to create a database in MySQL Server 5.5. The database is created, I know this as when I do SHOW DATABASES; It shows me my database in the list of all databases from the commandline. ...
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3answers
848 views

Replication or Sharding for a huge table?

I have a table that I'm pretty sure in the very near future (within a year) will reach 14 million rows, and I'm trying to scale out my web app before hitting any bottleneck. I'm in dilemma whether I ...
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6answers
52k views

Can't connect to MySQL database over SSH with Workbench

I'm trying to connect to my database via SSH tunneling from one of our web app servers with MySQL Workbench. Here's the basic config; note that I changed some values in the screenshot for security ...
2
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2answers
1k views

mySQL 5.1 changed innodb_log_file_size getting error on restart

In order to optimise my MySQL 5.1 (running on Window 2008 WebServer). I changed a few InnoDB options in my.ini namely the innodb_buffer_pool_size and innodb_log_file_size. But now when I am trying to ...
2
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2answers
1k views

MyISAM table keeps crashing. What are my options?

My MYSQL table is very large (250GB, around 200M rows). Recently I've been putting it through a lot -- parallel processes that do a large number of reads. It has started locking and crashing with ...
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4answers
4k views

Optimize Query with Derived Table

I have the following query select ps.id, ps.title , IFNULL(s.likes,0) as num_likes , IFNULL(s.comments,0) as num_comments , IFNULL(s.ratings,0) as num_ratings , IFNULL(s.views,0) as num_views , ...
2
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2answers
1k views

InnoDB not enabled

I have a mysql database that when I run SHOW ENGINES; innodb does not show up as an engine. This seems strange as I have an identical server setup where innodb is enabled and in use. I have checked ...
1
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1answer
1k views

Good strategy to replicate MySQL data

I'm working on MySQL database, well i have a master instance and slaves, and i need to add a new slave to Master. I adopt a simple strategy to do so: Stop slave, import data to new slave, and finally ...
5
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3answers
2k views

How to resolve the master server shut down/unavailability in mysql with master - slave replication

Let us suppose that we have a master/slave setup and the application is running fine for the time being. All of a sudden the master server suddenly shuts down due to some problem. Now how can I ...
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1answer
3k views

Changing MASTER_CONNECT_RETRY - Anything pit falls to keep in mind?

We run your basic Master + Multi-slave mysql replication setup. We would like to lower the MASTER_CONNECT_RETRY parameter on each of our slaves. Is there anything beyond re-executing CHANGE MASTER ...
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2answers
4k views

How can I optimize performance on a MySQL ndbcluster?

So, this is what I have: A simple table classes__to_students: |class |student| --------------- Math Alice Math Bob Math Peter Math Anne Music Bob Music Chis Music ...
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1answer
7k views

Copy blob from one row to another

I have a corrupt blob in a row. I'd like to replace that with another blob from the same table. How can I do that with sql statements only? (No file system access if at all possible.)
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3answers
27k views

mysql auto adjusting max connections values

I have set max connections to around 2000 in my.cnf file. max_connections=2048 I have upgraded to 5.5.20 and now I see the following line in the error log. 120201 19:40:24 [Warning] Changed limits: ...
3
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1answer
3k views

can mysql cli exit with error if no records returned?

I would like to execute a sql command in bash, and do something based on whether or not there was a result. e.g. $ LOOKUP=123; mysql -e \ 'SELECT id FROM table WHERE id='$LOOKUP dbname \ &...
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4answers
3k views

how to set default charset while create new field

Is there any command in mysql that makes the following: if I create a new field and I set the type to TEXT than it automatically knows that by this I mean not latin1_swedish_ci but utf8_hungarian_ci ...
2
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1answer
922 views

MySQL wont start after modifying /etc/my.cnf

I have Linux Red Hat 5, with Zend Server and MySQL Server installed. I am trying to change the default MySQL port to 512. However, after making this change, MySQL will no longer startup. I get the ...
3
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1answer
2k views

mysql: find column data size on disk

I have fairly large MyISAM table with longtext field in it Table size is somewhat 16GB. I need to know if clearing this column in old records helps to keep table small I can retrieve table wise ...
14
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6answers
13k views

Splitting Tables in MySQL. Good practice?

I have started working on an existing project and the previous developer had split up a table into 10 separate tables with identical schemas but different data. The tables look like this: [...
4
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2answers
3k views

pt-table-checksum with slaves using non-standard ports

Trying to run pt-table-checksum to detect slave drift in MySQL replication. My slaves are not using the standard TCP listening port however, and so when I run the tool I get an error: Cannot connect ...
1
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3answers
713 views

Is any tool for taking MySQL Dump Automatically with a particular time? [closed]

I am using VS2010 and MySQL for my project. My client wantw to take mysqldump every day like a daily backup. I want to give my client a tool for taking mysqldumps on a particular time schedule. Do ...
2
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2answers
13k views

Time to import an sql dump

I'm currently uploading one of Wikipedia's dump files. It has 1GB compressed and ~7GB uncompressed. It has been importing it for 6 hours already. The size of the imported table in MySQL is at the ...
5
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1answer
1k views

Quick MySQL Backup (1 file per table)

I asked a relevant question few months back and got answer with wide variety of options for backup. But this time I have different scenario and I have got a database with 7 tables and 1 of them has ...
4
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2answers
4k views

How to keep one query from slowing down entire database?

Using MySQL 5.0.x, we have a process to generate benchmarks for our business that consolidates a bunch of data, then pull out data based on certain criteria. This process used to take 18 hours, it's ...
7
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3answers
7k views

How much memory will a MEMORY table take up?

Let's say I have a MyISAM table with a data length of 4.8GB and an index length of 6.2GB. So, a total data size of eleven gig. How much memory would this require, were I to convert it to a MEMORY ...
4
votes
1answer
5k views

Not enough space for MySQL optimize; do new rows overwrite existing data?

My MyISAM table consumed most of my disk space. I deleted a significant portion of the table, but the optimize command (to clean out the deleted data) does not have sufficient space. Is there any ...
1
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1answer
404 views

mysql event running at wrong time

I created an event to run every 24 hours and be run at 14h. Its selects some data from tabels and writes it as to a file (csv format) The query and writing to file goes ok. The event is triggered. ...
4
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1answer
2k views

mysql change schema on the fly

Recently I faced the problem that my Db became very huge and I cannot allow to myself downtime every time when I want to change the schema. This caused me to start looking for solution that do schema ...
11
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2answers
13k views

move data folder and drive mysql centos

i need to move the data to a different folder and drive on my cent os db server. i added new hard drive (since we ran low on space), i have a 1tb of hard drive and i have a new 2tb i want to put the ...
1
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1answer
972 views

MySQL Cluster: cannot start the management node

When I try to start the management node of MySQL Cluster on Windows platform, I get the following error: Could neither create or open key 'SYSTEM\CurrentControlSet\Services\EventLog\Application\...
1
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1answer
998 views

I am getting an error while trying to download binary for mysql 5.5.11

I am trying to upgrade MySQL 5.1 to 5.5.11 on Ubuntu 10.10. Everytime I try the wget command I get this error: wget http://dev.mysql.com/get/Downloads/MySQL-5.5/mysql-5.5.11-linux2.6-i686.tar.gz/from/...
5
votes
4answers
14k views

Is MySql locking table during backup and how to avoid?

I have a scheduled backup that runs daily in MySQL and I have noticed that during the backup a lot of queries that query a frequently used table seem to take forever to complete. This causes the ...
2
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1answer
3k views

importing myisam 5.0 database into a 5.5 innodb server

I have MySQL 5.0 and 5.5 servers (but not a 5.1 server). The 5.0 server is myisam only, the 5.5 default is innodb. I need to move a database from the 5.0 server to the 5.5 server. The database is ...
7
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2answers
38k views

MySQL - CSV UPDATE (not INSERT) into existing table?

I have a table with the following columns: id | name | city The table has 1000 entries in it. I have a CSV file with a limited number of lines like this: id,city 34,Denver 45,Kansas City 145,New ...
3
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1answer
5k views

I have lots of free memory. How do I use it to increase performance?

I am running Litespeed (with suExec, PHP SAPI), MySQL, DirectAdmin, named on a VPS with a 16-core Xeon CPU and 2GB RAM. Currently, only 300 MB out of 2048 are used. It might sound a stupid, but how ...
5
votes
1answer
951 views

Mysql crashed once with an “Assertion failure” this morning, how worried should I be? best way to diagnose this?

So for the first time our production system produced the below assertion failure. The system came up without issues after mysqld automatically restarted itself and rolled back some transactions.. ...
1
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1answer
4k views

updating mysql primary keys

I need to be able to swap values that are used in a primary key. Meaning, in one update statement, I need to change id 1 to id 2, and id 2 to id 1. In other relational databases, (Sql Server and ...
3
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2answers
3k views

MySQL Replication via DNS Failure

I'm having some trouble using replication when the machines are configured to use host names instead of IP addresses. The "skip-name-resolve" is OFF. If I use IP addresses, everything is fine. Using ...
49
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5answers
73k views

Why is DROP DATABASE taking so long? (MySQL)

New CentOS installation. I was running an import of a large DB (2GB sql file) and had a problem. The SSH client seemed to lose the connection and the import seemed to freeze. I used another window to ...
3
votes
1answer
507 views

How can I find the user who performed a database transaction?

I am using MySQL database. Suppose a database "X". It is used by multiple users. I want to find those users who performed any transaction of data into this database. Is it possible? Can I find it ...
2
votes
1answer
781 views

“SQL_NO_CACHE” for innodb buffer pool

I'm guessing the answer is no, but I was wondering if there was anyway to tell innodb to not store fetched pages in the buffer pool? The reason for looking at doing this is check summing tables. I'd ...
2
votes
1answer
172 views

MySQL optimization question — how to speed up a simple query

I have a very simple database, one table with five columns (one INTEGER key, two VARCHAR, a DATE, and a DOUBLE). The table contains 909,000 records. A simple query like SELECT t.price FROM commoddb....
5
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1answer
9k views

Mysql fulltext search my.cnf optimization

I have open a question on https://serverfault.com/questions/353888/mysql-full-text-search-cause-high-usage-cpu Some user recommended asking here. We built a news site. Every day we will input tens of ...
3
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2answers
777 views

MySql - find redundant indexes

is there a tool that spots redundant indexes in MySql? e.g. if I have the following indexes: index1(col1) index2(col1,col2) then index1 should be flagged as redundant. any ideas?
3
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1answer
1k views

MySQL text field without quote

I've just run into something strange. The base_id is a varchar(255). When I do a SELECT without quote, it scans the whole table: mysql> EXPLAIN SELECT sid FROM rf_fo.scald_atoms WHERE base_id = ...
4
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2answers
1k views

Less RAM than Index_length MyISAM

I'm working on a database to store "time series" data (the value of X was Y at this time). The rows themselves are very small and static in size, with the primary key consisting of two smallint ...
2
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1answer
1k views

MySQL Tuner OPTIMIZE and Defragmentation

I have just started using mysqltuner to help keep my mysql server fast and healthy. However, I am having a little trouble optimizing my tables. When I execute mysqltuner, it all works fine and returns ...
2
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3answers
148 views

MySQL operations on grouped fields

I have one table t1 like this a|b|c -|-|- 1|1|2 1|1|3 1|1|6 1|2|3 1|2|4 1|2|7 1|3|5 2|3|2 I would like a query where the results would be similar to running multiple selects like this: (SELECT * ...
3
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1answer
1k views

mysqladmin debug writes out Current locks but PROCESSLIST and INNODB STATUS don't show any

I'm using the 1.1.8 mysql-cacti-templates to gather metrics on MySQL 5.0.77 (CentOS 5.7). Both the InnoDB Current Lock Waits and InnoDB Lock Structures graphs are charting with Cur[rent] values but ...
8
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1answer
4k views

Substantial difference between database size under MySQL and actual size on disk

When I check the size of my databases under MySQL I get this: MariaDB [(none)]> SELECT table_schema "Data Base Name", sum( data_length + index_length ) / 1024 / 1024 "Data Base Size in MB", sum(...
2
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1answer
4k views

mysql error log issue

I have mysql server running successfully. The error log location is as.. mysql> show variables like '%log_erro%'; +---------------+------------------------+ | Variable_name | Value ...

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