MySQL : Open-Source, Relational Database Management System

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InnoDB Failure of some kind

I have MySQL 5.5 installed. I tried to install Joolma but it failed. I went into their sql and replace EGNINE=InnoDB with MyISAM and the install worked. InnoDB is listed under SHOW ENGINES; Any idea ...
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87 views

Install MySQL on Ubuntu 12.0.4

This is my first time using Linux. I am trying to install MySQL 5.6.15 on an Ubuntu box. I download MySQL from their website and put it on a USB stick then plugged the stick into the box. How can I ...
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1answer
26 views

MySQL hangs in killed state

I have a strange situation where a mysql OPTIMIZE query will never end. After killinh it, it remains in the "killed" state. Scenario to reproduce: OS: CentOS 6.5 MySQL: 5.6 Engine: MyISAM (with at ...
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87 views

MySql - is possible that performance issues are caused by dynamic SQL?

We have this MySQL SP, which uses dynamic SQL. It seems it does NOT perform well under load. It is possible that this SP becomes slow under load because it uses dynamic SQL? Can dynamic SQL cause ...
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32 views

Optimize this query: SQL

I have this query in MySQL: SELECT p.idSentence, p.idPath, p.token, p.posTag, p.ner, p.isTV, r.relationType, t.tag FROM path p LEFT OUTER JOIN relation ...
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How to fix slow LIMIT queries with big offsets without heavily rewriting them?

Imagine a very basic example of your average discussion board. For example: CREATE TABLE threads ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, title VARCHAR(100), PRIMARY KEY (id) ) CREATE ...
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214 views

How to removing or reduce the size of redo logs in MySQL cluster

Can anybody tell me that how can we reduce the redo log file size or can we remove the redo log file size in MySQL Cluster and also what will be the impact of it on performance of cluster.Also can we ...
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54 views

When do I need transactions /locks?

I know that transactions are meant to group several operations as one. But if for example in the same table one transaction does DELETE FROM table where state = 'done' and another does either SELECT ...
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17 views

mysql synchronisation

hello, i have 5 MySQL servers masters each one have mysql slave , and i have to synchronize data from those masters to one other mysql(central mysql who contain the common data : it can be ...
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0answers
19 views

Can I set a lower_case_table_names value for a specific database?

I'm running a MySQL 5.5 on Linux (Debian 7) with several databases. I need to import a database originally maintained in Windows MySQL using sqldump. My issue is that this database is used by a ...
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1answer
121 views

Repeated values in group_concat

I have two tables, first the table food and Second is Activity: INSERT INTO food (`id`, `foodName`) VALUES (1, 'food1'), (2, 'food2'), (3, 'food3'), (4, 'food4'), (5, ...
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62 views

MySQL Replication Master push to Slave

I have two servers that need to be synced. One is online and has a public IP address. The other is internal and has no public IP address - nor is there a way to get it a public IP so that's off the ...
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28 views

How can I execute multiple statements at once in MySQL Workbench?

I'm trying to execute multiple LOAD DATA INFILE statements at once using MySQL Workbench. However, they execute one at a time. Anyway of forcing them to run in parallel? Thanks for the help!
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7 views

Is it possible for unique key to break master-master replication in mysql?

I have a master-master mysql setup with 2 servers running the exact same application making writes to such a table: CREATE TABLE `metric` ( `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, ...
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1answer
551 views

How much data is needed to show MySQL Cluster's performance scaling vs. InnoDB

I am evaluating MySQL Cluster as a possible replacement for an InnoDB schema. So far, I have tested it with 10s of MB of data, and found MySQL Cluster slower than InnoDB; however, I have been told ...
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1answer
99 views

Amazon RDS - Can't access MySQL DB from local machine

I read many questions/answers here but they are from a different interface from AWS Console. I created a DB Instance but can't create a rule in the security groups that's allows me to connect from my ...
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1answer
60 views

MariaDB: Created_tmp_disk_tables high after start

today i looked in the status of my MySQL server which is based on MariaDB and i noticed that Created_tmp_disk_tables is very high (over 168k). I think this is the reason for my high I/O usage. I try ...
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2answers
86 views

Abnormally high MySQL writes and larger than normal Binary Log files. How can I determine what caused this?

We have a MySQL master database which replicates to a MySQL slave. We were experiencing issues where MySQL was showing a high number of writes (but not an increased number of queries being ran) for a ...
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1answer
316 views

MySQL SELECT query hangs - Opening Tables INNODB

On my server I have 6 MySQL databases. They all power Wordpress websites. For some reason, 2 of these databases are not accessible. To my knowledge they use INNODB, but I can't confirm it as even ...
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1answer
5k views

Mysql slowly uses memory until it starts to use swap

I am running a 1gb of RAM rackspace database server. For some reason in about 2 days the memory usage goes from using very little swap, to using 100mb. If I don't restart sql it will keep using more ...
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1answer
46 views

How to organize the tables of a MySQL database with several statistics data of several years?

I am developing an app that must provide statistics information about the distribution of the money that a person spends each year in taxes in the city where he lives. The user should select the ...
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1answer
142 views

MySQL select by primary key against 100M of records within 30ms

I have no expirience with MySQL and database performance tuning in general. Wondering whether it is possible to perform a large number of selects against 100 millions of records by primary key within ...
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29 views

Why does the delete/update block each other in this case?

The following drives me crazy. I have: session1>begin; session2>begin; session2>update dummy set salary=1000 where id=11; session1>delete from dummy where id=1; id is the PK ...
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1answer
43 views

MySQL DB structure with Main category and several nested sub categories

I am looking to create a set of fields on my webpage identical to what eBay uses on their category selection page when you are selling something. For my purposes I am doing motorcycles, power sports, ...
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23 views

What do spikes in InnoDB lock structures indicate?

I co-maintain a high traffic site similar to StackExchange. It runs MySQL 5.1 (working on replacing it with MySQL 5.5 or MariaDB). All our tables are InnoDB. MySQL goes down a couple of times a day. ...
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3answers
3k views

Is it common practice to mix InnoDB and MyISAM tables on same server?

I've got a single database of about 4.5GB running on a server with 8GB RAM. The vast majority of the tables are MyIsam (about 4.3GB), but I'm soon going to be converting some of them to InnoDB. (It's ...
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Big Mysql table optimization

I have a table that I use to cache google translate API answers. Table structure is orig_string and group are indexes Now it has more that 1million rows with 35000 distinct values in group field. ...
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3answers
1k views

Problem with MySQL subquery

Why does this query DELETE FROM test WHERE id=(SELECT id FROM (SELECT * FROM test) temp ORDER BY RAND() LIMIT 1); sometimes delete 1 row, sometimes 2 rows and sometimes nothing? If I write it in this ...
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1answer
2k views

“Waiting for initial communication packet” error 0 in MySQL

I am using MySQL server 5.1.51 on a Linux machine. The application was working fine for the last 32 days, but since yesterday a number of clients are not able to connect to the database from our ...
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1answer
36 views

mariadb 5.5.36 with innodb plugin

I installed mariadb 5.5.36 on a win32 system. Everything runs fine except innodb requests are 2 x slower than an identical MySQL installation. So I want to switch back to original innodb plugin to ...
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2answers
35 views

Is there a way to enable MariaDB MEMORY storage engine for every table?

I am new to MariaDB and interested in using it because I want to use MEMORY storage engine for every table. I read MEMORY storage engine on mariadb.com and it seems like I had to specify storage ...
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1k views

In place upgrade from MySQL 5.5 to 5.6.11 removes all users from user table

On Windows, I upgraded from 5.1 to 5.5 no problem. Copied my 5.1 data folder into my 5.5 instance Started mysqld skipping grants Ran mysql_upgrade All good, but going from 5.5 to 5.6: Copied ...
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514 views

Extract MySQL information from a compressed tar.gz file

I have a back up-of a MySQL database which is contained in a .tar.gz file - I need to restore it. I've never had to do this before. The only way I can access the database is through phpmyadmin. There ...
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1answer
40 views

Large RAM use after import database - ubuntu server

My new vps has 4 GB of RAM. Before importing database system use about 1,2 GB of RAM. When I import database, about 250 MB sql file, 25000 tables use of RAM goes to 97%. Htop showing 3302 mb in cache. ...
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39 views

How to verify data dumps between two MS SQL and MySQL

I'm trying to verify data exported from MSSQL and imported into MySQL is 100% accurate using MD5 hash. On Linux, I'm using md5sum and WinMD5 on Windows. The encoding is the same: UTF8. I tried both ...
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44 views

Mysql - Select To XML

I'm Building Audit Trail with Trigger, and want to convert the inserted / updated / deleted value into XML and store it into another table. my trigger look like this: DELIMITER $$ CREATE ...
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349 views

Efficient way to move rows across the tables?

This is somewhat long question as I would like to explain all details of the problem. System Description We have a queue of incoming messages from external system(s). Messages are immediately stored ...
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2answers
32 views

How to delete list of email addresses from MySQL database?

I have a list of invalid email addresses parsed in the following format; There are roughly 1500 invalid addresses, and I need to remove them from my myBB users. What SQL query can I run to remove ...
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1answer
67 views

mysql replication missed quite a lot SQL statement

I have set up a master/slave with mysql-5.1.73 The master's binlog format is "statement". The master and slave seemed running very well with slave status: Slave_IO_Running: Yes ...
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1answer
41 views

Slow MySql server - even on a super fast server

I have just upgraded my 12 year old server to a really fast new one. It is a dedicated server, Dell R620 1 x Intel E5-2620 (2.0GHz, 6C) CPU 32GB RAM - 4 x 250GB SSD RAID 1, in short vastly faster in ...
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1answer
243 views

MySQL select query result set changes based on column order

I have a drupal 7 site using the Views module to back-end site content search results. The same query with the same dataset returns different results from MySQL 5.5.28 to MySQL 5.6.14. The results ...
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1answer
128 views

How to rebuild entire MySQL data after server re install?

I have a MySQL server running with multiple databases in a 32 bit environment. I need to rebuild my system to a 64 bit environment. Is it possible to replicate the entire MySQL databases, users, ...
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1answer
296 views

MySQL table relations, inheritance or not?

Im building a micro CMS. Using Mysql as RDMS, and Doctrine ORM for mapping. I would like to have two types of pages. Static Page, and Blog Page. Static page would have page_url, and page_content ...
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3answers
45 views

How to repair, or drop/create a corrupted table in mysql?

Situation: I have a MySQL database with 104 tables, running locally on XAMPP on windows 7. All the tables have InnoDB engine. XAMPP MySQL is running as windows service. As front end I have PHP ...
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1answer
37 views

how many 'text' column a table could have in mysql? I have this error “Row size too large (> 8126).”

I'm working on a application which is kinda complex to explain how it works. But this is the situation I'm in, ------------------------------------------------------------------------------ FIELD1 ...
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11k views

mysql: Show GRANTs for all users

MySQL's SHOW GRANTS shows the permissions of the current user. Is there a way to log in as root and show the permissions of all users?
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173 views

Time series data for ad platform

I am trying to figure out how to store time series data for an ad platform I am working on. Basically I want to know some strategies/solutions for storing billions of rows of data so that I can ...
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1answer
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ib_logfile0 and ib_logfile1 got deleted

After restoring from a percona-xtrabackup without a preparation step, ib_logfile0 and ib_logfile1 were not present in the restore data. Therefor during startup the following message is observed: ...
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1answer
211 views

mysqldump freezing on a specific table

I dumped a database (sys_data) which is very big (800GB, all data in one ibdata file) from a remote server. But the dump was blocked at a table (tb_trade_376). My dump command: mysqldump -uxx -pxx ...
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876 views

Amazon RDS - Can't connect to MySQL database server?

So I've been working on this issue for a while now, and I'll explain what I'm trying to do. I'm trying to connect to a MySQL database server, hosted by Amazon Web Services in the Amazon RDS service. ...