MySQL : Open-Source, Relational Database Management System

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MySQL gives “Out of Memory” error when inserting a large file. From where is this filesize limitation arising?

I'm using a MySQL database to store files. The table I'm using is structured as follows: +--------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default ...
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1answer
1k views

Replicate MySQL 5.0 Master to 5.5 Slave?

We're planning out a series of server/software upgrades and were curious. We have a RHEL5 install running MySQL 5.0 that we'd like to replicate to a new (virtualized) server running CentOS 6 and ...
4
votes
1answer
7k views

What can cause TRUNCATE TABLE to take a really long time?

I'm running MySQL5.5 with Master/Slave replication (1 master, 2 slaves). I have a process that runs once a week and truncate a specific table. The table is not large and only has a few thousands ...
4
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2answers
424 views

Why is a secondary index chosen over a clustered index for SELECT COUNT(*) …?

In this query: select count(*) from largetable; a secondary index is chosen: mysql> explain select count(*) from largetable; ...
4
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1answer
2k views

Suddenly have to rebuild indexes to prevent site from going down

I have been having this problem for a while: http://stackoverflow.com/questions/7770695/mysql-query-slow-until-reindex-column It seems all is good and when I suddenly get a lot of writes to the table ...
4
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1answer
928 views

Determining max database and table size supported and present size

One of my MySQL databases has been running on a single PC from the last four years. Here is my setup: MySQL 5.5.14 Windows XP on NTFS partition All of my tables are using InnoDB engine Here are ...
4
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2answers
690 views

With MySQL Replication, what level of resilience is possible?

I've found lots of good material on setting up MySQL replication, but not much on what to do in the event of failures. Understanding the degree of resilience I can achieve is fundamental to designing ...
4
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1answer
844 views

How does max_allowed_packet affect the backup and restore of a database?

I have a database based on mysql 5.0.75-0Ubuntu10.2, running under Ubuntu 9.04. I have a table in that database with a medium blob column. I have been using automysqlbackup to do nightly backups/dumps ...
4
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3answers
554 views

Separate databases for front-end and back-end

The site I am working on has a lot of backend/cron activity, so there are between 5 and 15 queries being executed every second of the day. This can slow down page loads by a second or more. I was ...
3
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1answer
119 views

What if I want to keep using MyISAM

In my current use of MyISAM the databases are extremely small and kept for a few weeks after which time they are deleted and completely rebuilt with a clean slate. The script uses MYISAM tables and ...
3
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1answer
1k views

Binlog has bad magic number

I keep getting this error whenever I start MySQL. 121028 1:38:55 [Note] Plugin 'FEDERATED' is disabled. 121028 1:38:55 InnoDB: The InnoDB memory heap is disabled 121028 1:38:55 InnoDB: Mutexes and ...
3
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1answer
488 views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: ...
3
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1answer
360 views

Setting up MySQL circular replication in existing replication topology?

I have the following MySQL replication topology set up for fault tolerance/disaster recovery with master server A and slaves B and C: A replicates to B A replicates to C Both B and C are fully up ...
3
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2answers
3k views

Trying to understand SHOW SLAVE STATUS\G

I have slave setup and looks like it is running fine. Below is a snapshot of it. show slave STATUS\G; *************************** 1. row *************************** Slave_IO_State: ...
3
votes
2answers
499 views

Sorting the Table and getting the position

I am able to sort a table using the following code:SELECT * FROM Persons ORDER BY LastName But I wanted to get the ranking/position of a person using that order. For example when I sort Person table ...
3
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1answer
1k views

Does `Seconds_Behind_Master` show exact Slave Lag from Master?

Does Seconds_Behind_Master show the correct result? I have also Implemented the mk-heartbeat replication monitoring. It was showing the other result in comparison with Seconds_Behind_Master. Which ...
3
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1answer
1k views

Stuck outside MySQL! XAMPP - help please

I have been using xampp (on windows XP/XAMPP 1.7.4 /PHP 5.3.5) for quite a while now, and last morning I started to get some weird messages when I was developing my website, It happened yesterday and ...
2
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1answer
5k views

How can extract the table schema from just the .frm file?

I have extracted the data directory of mysql from a backup and need to get the schema from an old table, however it's a backup from a different machine. I have read a fair number of tutorials today ...
2
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1answer
760 views

MySQL upgrade 5.0.88 to latest

Very interesting and informative blog.. I have a question - i have a requirement of upgrading from 5.0.88 to latest version.. Why should i upgrade? if so, which version should i consider? What ...
2
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2answers
324 views

MySQL export user with semi-colon “;” on the end

I am trying to set up automatic export of user accounts from one server to import into another. I am running the following command; $ mysql -u root -p -B -s -e "show grants for 'myuser'@'localhost';" ...
2
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1answer
678 views

How does mysql deal with queries that touches myisam and innodb tables?

In our mysql database, we use both myisam and innodb tables, though there are more myisam tables. QUESTIONS If a query involves both myisam and innodb tables, will the query use table lock or row ...
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4answers
643 views

Backup and restore “mysql” database

I use the following command to backup some normal databases: mysqldump --host=host --user=user --password=passwd --result-file=result.sql -R --single-transaction database_name My question is : do I ...
2
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1answer
1k views

MySQL Slave Relay Logging but not logging Binary Log

I have a master slave setup both mysql 5.5, the setup is fine except that the slave won't Binary log to the standard mysql-binlog only to the relay logs. I fear this may be due to my lack of ...
2
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1answer
4k views

Mysql master-master replication auto flush old logs

I have mysql-5.1.41 master-master setup running on ubuntu machines and below is the configuration of a master: skip-host-cache skip-name-resolve event_scheduler = ON max_connections = 500 ...
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2answers
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Problem with InnoDB “per table” file sizes

I Have configured the mysql server with innodb per table. There was a table watchdog having approximate 19GB of watchdog.ibd file. I have truncated the table now it has zero record. But the ...
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1answer
300 views

How to do MySQL User Accounting

I can't seem to find any information on this anywhere. I found a question here called Monitor MySQL activity per database? but that's not quite the answer either. I'd like to be able to log the ...
2
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2answers
3k views

Table compression in InnoDB?

I have read that table index compression happens just in MyISAM, but I came across an article in dev.mysql that said: InnoDB supports table and index compression! So now what is the pros of MyISAM? ...
2
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2answers
477 views

Any problem will all InnoDB and one MyISAM table?

I have a MySQL 5.5 DB with all InnoDB tables. For some reason, one of the developers decided to create a MyISAM table. It is a log table for user sessions. I don't see why we should mix in a MyISAM ...
2
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1answer
3k views

Fixing MySQL errors recorded in error logs

Below is the extract of the most common lines of error being recorded in error logs on my PC: 110905 16:16:54 [Note] Plugin 'FEDERATED' is disabled. 110905 16:16:54 InnoDB: The InnoDB memory heap is ...
1
vote
1answer
313 views

query cache hit value is not changing in my database

The query cache hit value is not changing in my database only for some queries.If I write select * from drugs_info limit 1000; the query cache hit has changed, but if I execute the following ...
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4answers
3k views

Single slave - multiple master MySQL replication

I need to replicate different MySQL databases from multiple servers into a single slave server. How can this be done? is there a way to define multiple master hosts?
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3answers
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How to use 2 auto increment columns in MySQL phpmyadmin

Is it possible to use 2 auto increment values ? One starting from 0 Another starting from 4000400 Please help me
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1answer
154 views

Translating backup size to database size

I have a client who gave me a 4 gig datafile from mysqldump that I need to restore somewhere. Is there a good rule of thumb for translating the size of a backup into the size of the database once it ...
0
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1answer
95 views

MySQL (on Windows) general log too large to rotate properly?

First off, I'm not sure if this should go to Server Fault or Database Administrators. It could be a Windows Server 2008R2 problem. But I am asking here first in the chance that someone else running ...
173
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15answers
53k views

Can MySQL reasonably perform queries on billions of rows?

I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies ...
6
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2answers
12k views

What is the Best Way to create MySQL Master-Slave Replication Setup and Troubleshoot it?

I am very new to Database Administration. I face a lot of problems while setting up mysql master-slave replication. I also face regular mysql replication troubleshooting issues. Can anybody helps ...
11
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1answer
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Is it possible to have passwords configured per database or per host in .my.cnf

I have the following in my ~/.my.cnf [client] password="somepass" but this is not the password I use for every user@host/database I connect to. Is there some way to specify in the config different ...
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2answers
3k views

Performance of a Trigger vs Stored Procedure in MySQL

A post here on DBA.StackExchange (What are the best practices for triggers to maintain a revision number on records?) has spawned an interesting question (at least, interesting to me) regarding ...
7
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1answer
8k views

Should I increase max_connections in AWS RDS t1-micro for MySQL?

I have an AWS RDS t1-micro running MySQL 5.5. It gives me too many connections error. I checked and it allows 34 maximum connections concurrently. What I have read is that i can increase this max ...
7
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4answers
13k views

Why does MySQL say I'm out of memory?

I was trying to execute a fairly large INSERT...SELECT in MySQL with JDBC, and I got the following exception: Exception in thread "main" java.sql.SQLException: Out of memory (Needed 1073741824 bytes) ...
6
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5answers
11k views

How to properly kill MySQL?

I have CentOS 64bit with CPanel installed and I use service mysql stop However, it keeps doing ..... for minutes and it never stops. It used to be instant. Any idea why it does that and how to fix? ...
5
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4answers
3k views

MySQL: Index when joining to tables not being used (Performance optimizing question)

I need to optimize the following query: SELECT /* [things omitted] */ articles.blogpost_id, articles.id AS articleid FROM blogposts JOIN articles ON articles.blogpost_id = blogposts.id WHERE ...
9
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1answer
11k views

Mysql Innodb: InnoDB: ERROR: the age of the last checkpoint is InnoDB: which exceeds the log group capacity

I really need some mysql expertize. I am a newbi to mysql and I am seeing some server crash of my db in the past 1 week. I am using mysql 5.1.36 on Ubuntu. This is a dedicated mysql server with Dual ...
9
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2answers
7k views

kill all queries - MySQL

Sometimes during a SNAFU I have to run kill query xxxxxxx twenty or thirty times. Any sort of kill all command I am missing? On account of how I don't like typing.
8
votes
3answers
5k views

MySQL status variable Handler_read_rnd_next is growing a lot

In MYSQL status, Handler_read_rnd_next value is very high. I am aware that, this value will be incremented when a query is executed which is not having proper indexes. But, even when we execute ...
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2answers
3k views

What are the benefits of using MySQL Cluster?

I have never dipped my hands in MySQL Cluster and want to know how it can benefit me. When is it best to use it, and does it have performance benefits?
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4answers
10k views

Replicating a remote MySQL database to MS SQL Server 2008

I want to replicate the contents of a MySQL database to a MS SQL Server 2008 database. Is this possible? Can anyone outline the steps required in order to achieve this? Thanks.
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1answer
286 views

What corner cases exist when relying on undocumented behaviour to determine values selected by MySQL for hidden columns in GROUP BY operations?

Under GROUP BY and HAVING with Hidden Columns, the MySQL manual documents (added emphasis): MySQL extends the use of GROUP BY so that the select list can refer to nonaggregated columns not named ...
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2answers
8k views

Why do MySQL tables crash? How do I prevent it?

I'm the Administrator of a Moodle site which had its Users table corrupted and it became unusable. Luckily, a simple REPAIR TABLE mdl_user made it work back again. The thing is that I don't know why ...
5
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3answers
12k views

How to recover MySQL table structure from FRM files

What I have learned from Google searching: With MyISAM tables you can simply copy the FRM, MYD, and MYI files. In the folder for the DB I'm trying to recover, there are only FRM files and a "db.opt" ...