MySQL 5.5 brought many performance enhancements and expanded the feature set of the popular open-source RDBMS.

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output from mysqltuner.pl (from mariadb.service)

While running mysqltuner.pl script, I'm getting following message: [OK] Currently running supported MySQL version 5.5.35-MariaDB-log [OK] Operating on 64-bit architecture -------- Storage Engine ...
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12 views

mysql service failed to start when datadir changein ubuntu

I have dual Operating system on PC, windows 8 and ubuntu 14.0, and I am mostely using ubuntu because my MySql database is hosted on ubuntu. Recently when I am trying to restore my database, which is ...
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183 views

Mysql query is very slow

I am developing a website like any other social networking site using mysql. I wish it give people suggestion to my users, and I have implemented this functionality in my application, but It is ...
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2answers
139 views

Problem in Fetching Result set in Desired Format

I have 2 tables having the following columns Person ------ person_id, first_name, middle_name, last_name Items ----- person_item_id, person_id, item_type, status, ordered_date The query is ...
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1answer
25 views

MySQL database configuration for fastening the select and insert queries

There are several DBEngines are available for MySQL DB. Currently I'm using InnoDB. My actual problem is, I have a table that consist of millions of data. Therefore the select queries that given to ...
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13 views

What should I do if i forget password in MySQL?

I am using MySQL5.5. I trying to login in mysql from terminal by using "sudo -u root -p" But i could not remember password. How can i fix this problem?
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1answer
56 views

Installing MySQL in Solaris

I am trying to install MySQL 5.5 on Solaris 10. I executed the code useradd -r -g mysql mysql where a group called mysql is already created using groupadd command. I get the following error : UX: ...
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4answers
2k views

MySQL gives me:“Can't open and lock privilege tables: Table 'host' is read only”

I am facing problem restoring a MySQL database. My primary database was MySQL 5.1 and now I am trying to copy it to MySQL 5.5. The database was backed up by using Xtrabackup. I am using Ubuntu ...
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1answer
586 views

consequences of using “innodb_flush_method = O_DIRECT” without having a battery backed write cache? or on a KVM guest?

Mysql 5.5.29 Innodb- 128GB Ram - 32 cores - Raid 10 SSD. Our server which is a dedicated KVM guest on a 'baremetal' is hosting our heavy read-write DB server. Everything is file-per-table. ...
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1answer
140 views

Data Analysis with MongoDB or MySQL

I have a need for processing some data in order to come up with some statistic. This is the scenario: Each user can answer several questions from the question list. They pick their answers from a ...
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1answer
66 views

mysqldump 5.5.25 use swap instead of memory

mysql version 5.5.25, while use mysqldump to dump big tables, it eat lots of swap while there is lots of free memory. # free -m total used free shared buffers ...
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1answer
205 views

Two different MYSQl instances on same machine?

I have MySQL 5.6 installed (Linux). /var/lib/mysql /etc/my.cnf I have a cold backup that I am recovering: /var/lib/mysql_backup /etc/mybackup.cnf In April I was able to get the backup started ...
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1answer
32 views

Mysql improve Self join performance large table?

I have a task to help identify conflicting IP ranges , I want to highlight when one companies IP range falls within another's ... below is the sample table, I have converted the IP ranges from .dot ...
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2answers
33 views

MySQL user without SUPER privilege

This may be a simple question and may not be the right place to ask but I couldn't find any useful information from Google. Here is my question. When creating users in mysql using grant all ...
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2answers
48 views

MySQL Community Edition Capacity

I am using MySQL Community Edition on Amazon RDS service. It is a very large database, 2/3 tables has about 10 millions records and 4-5 tables has 7-8 millions records. Questions How much capacity ...
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2answers
75 views

Query only for the first n results of like

What I'm trying to accomplish is a huge speedup (read: incremental results) when searching a database with a like operator which is kind of a last resort, if everything else already failed, to come up ...
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1answer
39 views

Slow INSERT/UPDATE on InnoDB

I have a problem with the performance of my MySQL server, let me explain: I instaled a MySQL server, version 5.5.20 Server version: 5.5.20-log Source distribution SELECT queries runs fast on ...
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1answer
151 views

Restrict access to rows by usename

In my database i store data of different users (e.g. addresses or invoices) in the corresponding tables. I want to make sure that a logged in user only has access to it's own data in the tables (so ...
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9 views

A connection is in sleep for long time in MySQL

When I am looking in process list, three to five sleeping connections are alive. I can kill them but except one connection that is first one in above image. A user connected with information_schema ...
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4answers
7k views

How to change a MySQL previous slave to be a master and remove slave status information?

I have a master -> slave configuration where the master failed. I've been able to reset the old-slave to be a master and the old-master to slave from it. Fine. What I can't seem to do is to remove ...
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1answer
84 views

Unable to run update_mysql in MySQL 5.5

I have recently taken over managing a MySQL database running on Windows Server 2008 R2 . It is running 5.5.37 Community Edition. When it is started, it includes the following lines: Thread, Type, ...
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0answers
8 views

mysql compare databases and merge the difference

I have a mysql multi-master replication setup. Unfortunately replication has broke and have in consistence data among db server. Now i would like to merge all the databases and make it consistent. ...
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1answer
465 views

Convert Oracle Query for Date to Mysql queries

Need to convert the following oracle queries to MYSQL queries. 1) select to_char(to_date(?,'DD-MM-YY')) from dual; 2) select to_char(next_day(to_date(?,'DD-MM-YY'),'FRIDAY')) from dual; 3) ...
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7 views

Recovery database from masters

I have a multi master setup with 3 mysql nodes with Tungsten, Unfortunately replication has broke between 3 servers. Now the data is inconsistent say 100 users data is in node1, 100 users data in node ...
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24 views

tables don't exist after unmounting and remounting external drive where database was installed

I want to create a database that's too big to keep on my own machine, so I'm trying to create one on an external hard drive. It works up until I unmount and remount the drive, at which point show ...
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1answer
182 views

wordpress table is crashed and should be repaired

I run a wordprees website and use a managed VPS server with cPanel/WHM. Got bellow error log and check the table. I repaired the table with repair table command from phpmyadmin. But this problem occur ...
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4answers
221 views

Aggregate query optimization

Could you please help me to optimize this query - currently it takes ~4 minutes to run this query. It looks like keys: ip and timestamp are non-unique so shall I add some indexes? mysql> EXPLAIN ...
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1answer
23 views

ON DELETE CASCADE pseudo delete

For data integrity ON DELETE CASCADE is necessary but it's really dangerous when a delete affects like a Chain Reaction! I know one way to prevent this is to make a pseudo delete by putting a ...
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1answer
37 views

Select post and concatenating all categories it belongs to

I have 3 DB tables POSTS +----------+----------+----------+ | id | title | content | +----------+----------+----------+ CATEGORIES +----------+----------+ | id | title | ...
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3answers
95 views

Will redirecting queries to dev/null warm up indexes?

I'm trying to warm up the buffer pool. Will running a query and re-directing the output to /dev/null suffice? e.g. mysql -u username -p -e "select id from tbl where 1=1" > /tmp/results.txt Thanks
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1answer
56 views

want to download 3GB database table from my development mysql server [duplicate]

I need to download database structure with data. Total size of the DB is more than 3GB. If i use phpmyadmin it is not working. I have also tried by increasing the execution time in php.ini. I need ...
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1answer
60 views

Master-Master Replication Duplicate Key

I have set two servers master-master replication mysql , i manage to set successfully but the problem is the duplicate key i got MASTER 1 Configuration /etc/my.cnf [mysqld] server-id=1 bind-address ...
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3answers
207 views

What happens when we take a timediff between timestamp and datetime

Say I have following table in mysql (5.5+): CREATE TABLE IF NOT EXISTS `test` ( `id` int(11) NOT NULL, `x_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, ...
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Query to retrieve data based on several where conditions ( Not off Topic , Answer provided below is right ) [closed]

Database : Mysql 5.5 i have a table T1 containing 4 columns : No. , Height , start_time , end_time In column height i have 3 distinct values only : Small Medium High Now i ...
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1answer
51 views

Slow queries InnoDB occasionaly

I have the next table: CREATE TABLE `sessions` ( `session_id` char(32) COLLATE utf8_unicode_ci NOT NULL, `session_expires` int(11) NOT NULL DEFAULT '0', `session_data` varchar(10000) COLLATE ...
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21 views

Rails with mysql 5.5 update queries take long

app was running Rails and MySQL 5.1 and worked quite well. When we have upgrade to the new server with MySQL 5.5 some update and delete queries started to work quite long (1 sec vs 50ms on old ...
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19 views

Log-slave-updates in multi master replication using Tungsten replicator

I m setting up a system as follows with 2 masters and 2 slaves. M1 <----> M2 (Tungsten Replication) M1 ----> S1 (MySQL Replication) M1 ----> S2 (MySQL Replication) I have enabled the ...
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45 views

Refactoring IN Subquery, Avoiding Query in a Loop

I've got a table which was designed as both the current data set for participants, as well as being the historical changeset for those participants. This table has been in use for approximately three ...
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1answer
30 views

Is there a product to auto-build indexes based on slow queries?

I'm looking to either find, purchase, or write a script to identify slow queries, identify potential missing indexes, and when needed create the appropriate index within a reasonable amount of time of ...
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2answers
35 views

Mysql replication from existing slave to new slave

I'm hoping you experts can help advise me, I've got this topology: Live DB(Master) ----> Backup Server (Master and slave) ----> Test DB Backup server is a slave of Live DB, and Test DB is a slave of ...
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45 views

Create Drop Temporary Table very slow vs Truncate

I've got this stored Procedure that is called by an event that runs every 1 minute. The stored procedure selects some data from one device and puts it in a temporary table. Than it picks up other ...
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19 views

MySQL Procedure call is limiting parameters to 3 characters

I am running MySQL 5.5 using MAMP on my local machine. I have imported a database that was exported from a Windows Development environment. To get my Procs to run correctly locally, I had to change ...
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2answers
18 views

Joining on 3 different keys as they're set

I have these tables: TABLE vessels ID int PK organization_id int FK fleet_id int FK name VARCHAR TABLE settings ID int PK organization_id int NULL FK fleet_id int NULL FK vessel_id int NULL FK ...
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36 views

Upgrade from mysql 4.1 to mysql 5.5

I was going through upgrade process of mysql server. It is mentioned that to upgrade from 4.1 to 5.5 we need to upgrade step by step like first to 5.0,5.1 ...5.4 and then 5.5. I have some questions : ...
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0answers
20 views

MySQL slow query log not logging all slow queries [duplicate]

I am trying to analyze the hibernate query performance in our application. I tried logging all hibernate queries which take more than 100ms execution time from application side as well as using mysql ...
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11 views

Will performing a physical copy of a MySQL database on Windows to a MySQL instance on Linux still perform? [duplicate]

I'd was told you can copy text files and such from Windows to Linux just fine, I was wondering if I could copy my innodb files such as .ibd and .frm files to a mysql instance running on Linux, fire it ...
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How are performances with InnoDB auto-extending data file

Our innoDB tablespace is configured like this: innodb_data_file_path = ibdata00:40G;ibdata01:40G;ibdata02:100M:autoextend If I take a look to the directory: [root@xxx innodb]$ du -hs ...
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28 views

stress testing mysql - maximizing qps for a single user

I am running a stress test and I am trying to churn out as much qps as I can for a single user. I know this is a loaded question so I will try to be more specific. Trying to target 30,000 qps with a ...
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1answer
30 views

Will composite indexes or unique indexes help with query performance?

I need help with identifying indexes to increase performance of the following query. I'm currently using v5.5 with InnoDB. I cannot modify the query. However, I can add indexes as needed. The ...
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1answer
2k views

Error “#1118 - row size too large” on the first row of the table only

I ran into a problem using a mySQL database. I have some columns as type text but when I try to enter data into the first row I get the error code "#1118 - Row size too large. The maximum row size for ...