MySQL : Open-Source, Relational Database Management System

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Error 2003: Setting up MySQL Replication

Trying to setup MySQL Replication using this guide here : http://wpguru.co.uk/2013/05/how-to-setup-mysql-masterslave-replication-with-existing-data/ I was able to do this on two random VMs running the ...
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How to do Mysql migration from 5.0 (320bit windows) to 5.6 (64 bit windows)?

I want migrate My Mysql 5.0 windows 32 bit to Mysql 5.6 Windows 64 bit? Please suggest me the best way to do migration, i have around 10gb of data present in Mysql 5.0.
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Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. We ...
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Java Spring application Database triggers auditing - how to provide the right user that made the change

We are developing a new web application. one of the most basic requirement is to audit all entities changes into a separate table. We would like to use DB triggers for that purpose. We use MySQL as ...
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SQL Server to MySQL migration using MySQL workbench

I tried to migrate database from SQL Server 2012 to MySQL v5.5. I used MySQL workbench v6.1 community edition. What I was migrating is just schema only, not for the data. I got this error Reverse ...
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MySQL Workbench run SQL script file Character Set encoding issue

Upon running a .sql file for creating a schema in MySQL Workbench 6.1, it prompts a window saying it cannot decide the right character set What's the proper thing to do?
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MySQL Utilities seems outdated?

http://dev.mysql.com/downloads/utilities/ has MySQL Utilities 1.4.4 for Mac OS X 10.7. Is this still updated and recommended to use along with MySQL Workbench? I'm at the latest MySQL Workbench 6.1 ...
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How to make MySQL log to 2 seperate remote servers?

Documentation on this topic is scarce at best. I have two syslog servers and i need to send MySQL logs to them. Currently, i believe the logs are stored at either .mysql_history and/or mysqld.log Does ...
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How to make MySQL log to 2 seperate remote servers?

Documentation on this topic is scarce at best. I have two syslog servers and i need to send MySQL logs to them. Currently, i believe the logs are stored at either .mysql_history and/or mysqld.log Does ...
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11 views

Can having a LIMIT on DELETE degrade performance dramatically?

I have a database project in php and mysql. For, hopefully redundant, data security I added a LIMIT 1 to the delete($uniqueID) php function we use. Nobody cared because records really aren't ...
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MySQL starts from shell but doesn't start from MySQL Workbench

Being in need for MySQL database for a Django project i performed its installation from official website. It starts well from bash shell though "sudo service --status-all" shows status like this - [ ? ...
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EXPLAIN (with subqueries) is giving results I don't understand

I have a query that relies on a subquery, and that subquery relies on another subquery. When I run an EXPLAIN on the full query, in does a full table scan of the table in the primary select. However, ...
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How do I prove that the act of removing foreign keys doesn't corrupt existing data?

TL;DR: Prove that in practice, the execution of the alter table table_name drop foreign key constraint_name statement does not corrupt existing data. The important consideration is the execution of ...
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26 views

Schema for multi-account database

I'm building an app which will have accounts for organisations leading to organisation.myapp.com subdomains for their account access. I'm putting together the schema for it and I have a few ...
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34 views

Why is there no data loss with mysql innodb_flush_log_at_trx_commit set to 0?

Here is the MySQL info: mysql> show variables like 'innodb%flush%log%'; +--------------------------------+-------+ | Variable_name | Value | ...
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29 views

Planning on building a big web service. What kind of developers do I need? [on hold]

I'm a designer. I'm looking for web/mobile developers to help me build a similar platform like Airbnb or Yelp, but I don't know a lot about backend or on what technologies these two sites are built ...
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18 views

Count(*) as rolecount, filter by rolecount = 1

How can i filter out the rows who only got rolecount = 1? WHERE rolecount = 1 gives an error. Can't really figure out how to do it. SELECT u.uid AS uid, u.name AS name, u.picture AS picture, ...
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28 views

Does it make sense to run a cluster of database servers in docker containers?

I'm currently looking into setting up a database cluster (MySQL Galera or Percona) but I have only 2 machines. However, according to many sources I've read (This article from the Mariadb KB), the ...
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14 views

how to store complex data using mysql and jsp

At present i am doing small web application called slam book .We know slam page contains so many fields .By using mysql tables it takes too many columns and leads to complexity for accessing the ...
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mysql 5.6 gtid replication: is log_slave_updates required?

I've read the docs saying log_slave_updates is required. It makes sense for a general promotion situation. But is that really still required for something you're intending to be a read only slave ...
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16 views

MySQL Cluster lock wait timeout exceeded when trying to deal with huge amount of queries

I'm trying to deal with many connections and sometime I get following error: ERROR : Lock wait timeout exceeded; try restarting transaction The bigger number of queries the least number of ...
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18 views

Generic Trigger on MYSQL to replicate data on other table

I'm currently doing a history table that basically logs every single modification in a history table, and adding the Action executed. CREATE TABLE `competencies` ( `id` int(11) NOT NULL ...
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2answers
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Strange issue with MySql 5.6 replication

I have a strange issue with MySql 5.6 Master-Master replication. I'm not sure if its entirely a replication issue or a client issue. We have two MySql databases on two different RHEL servers. We have ...
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16 views

mysqldbcompare - ERROR: The list of objects differs among database

I'm running: # cat /etc/redhat-release Red Hat Enterprise Linux Server release 6.5 (Santiago) # rpm -q mysql-server mysql-server-5.1.73-3.el6_5.x86_64 # and mysql> SELECT VERSION(); ...
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27 views

Connect to a Remote MySQL

I'm trying to connect to a MySQL remote Server but I always get: RROR 2003 (HY000): Can't connect to MySQL server on 'IP' (111 "Connection refused") I follow this rule in the remote server GRANT ...
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22 views

Insert results of concat

I have a table with 4 columns: ID ORDER_ID QTY VALUE 1 153 1 0 2 476 1 0 3 453 9 1 4 719 2 2 ...
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MySQL: What are the pros and cons of running with engine=Memory vs on a memory-mapped filesystem?

What is the difference (in terms of read and write perf, alter tables, backup and recoverability and consistency) of running a MySQL database on a memory-mapped filesystem vs with ENGINE=MEMORY
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Why do these two queries (which I think are equivalent) rely on different keys?

We have a query that we don't like, since it ends up doing a full table scan. EXPLAIN SELECT count(*) AS c, location.name FROM study LEFT JOIN location ON study.location_id = location.id ...
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MySQL Join, Force NULL Row

I'm having a bit of trouble figuring out how to do this -- I need to select all rows from table t1, join table t2 -- but include a null row from t2 for each record in t1 (even if rows match in t2). ...
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8 views

How to append value of column with double quotes (add quotes around string)

I have a table with a column that is TEXT type. In the column are numeric characters. What I'm trying to achieve is to wrap those characters in double quotes. EXAMPLE: NAME ID QTY Apples ...
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31 views

creating a 24 hours data table - Suggestions/improvements

I am planing to have a table to store the data based on every hour , in short I have a file with 24 hour data and I need to use this to populate a hourly bar/line graph. Below is a sample 24hr data ...
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43 views

1 million strings and exact match search

I need to chose the best solution (software and algorithm) to solve my problem. I need to store up to million strings and data associated with them. Strings are search queries and data is cached ...
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26 views

select where index + other field

Learning indexing I have made an index, consisting of usergroupid and birthdate I understand that queries will then benefit from indexing when searching usergroupid and/or birthdate But what ...
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25 views

how to optimize grouped select from an already grouped select query

I already had a specific query to get a number of shops, but I couldn't sum the cost field, I kept on getting an error on the sum function, but it worked when I did this; select tab.shop_id, ...
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Split in and out for attendance machine system

I am using PHP and MySQL to create an attendance system. I have this table: +----+----+------------+-------+-------+-------+-------+-------+--------+ | id | pd | date | in1 | out1 | in2 | ...
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Nesting multiple INNER JOIN within LEFT OUTER JOIN in sql on deifferent side of keyword

I am having some problems with one of the question's answered in the book "SQL FOR MERE MORTALS". Here is the problem statement Problem Statement Here is the Database Structure The Database ...
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17 views

Multi Replications Plan on 2 servers

I need some advice about our new database deployment plan. We have 6GB of total mysql data(all innoDB) and innoDB_buffer_pool is set to be 16GB Ans we have 2 database servers.(plus 1 server for the ...
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20 views

Multiple Queries with overlapping results and column level permissions

Sorry for the obtuse Title, I'm having a hard time knowing how to summarize. I'm trying to do this with pure SQL(mySQL) and server-side(Perl) data manipulation. A user table is defined: id, uid, ...
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26 views

High Traffic Errors - Unknown Cause

I came into work on Monday morning to find problems all over our shopping cart website. I've tracked the problem down to what I believe is unusually high database traffic – several gigabytes in just ...
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Correct Schema Design for form builder?

I'm attempting to build a form builder app that allows users to: signup build a form store the data from that form into this db. I have designed the following schema: ...
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1answer
45 views

Determining what query was called

I want to reverse engineer what exactly happens to the MySQL database when a product is added in Magento. I will have to reproduce the query, because I would like to manually enter new records using a ...
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41 views

Finding reason behind high write IOPS on MySQL (RDS) server

I am having performance issues with an AWS RDS instance (running MySQL 5.6). This is the backend db to an XMPP server called Tigase. According to Tigase Inc. this type of db instance should be able ...
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Combine two mySQL sum queries into one which use different where clauses

I have two sum quires referencing different tables in mySQL. How can I combine the two in order to calculate the difference between the two values for each user in the database? Query 1: SELECT ...
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How to change the domain name or IP address in mysql database in every tables

I was using Openfire chat server in Ubuntu, whose IP address was 192.168.1.15. Then, I wanted to move it to other ip (192.168.1.55), so i took a backup of my database. The database I was using is ...
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29 views

Can a slave with a dynamic ip update the master

How can I setup mySQL replication in such a way that a slave on localhost with dynamic IP can update the master as well as get updates from the master which has a static IP. The slave will not be ...
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32 views

How do I fix and prevent corrupted MySQL tables?

We have developed software that uses MySQL. After some months of usage, some of the database tables had been corrupted and need to be repaired. Because of the corruption,we are not able to create a ...
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Is this statement syntactically correct?

$q = "SELECT var1, var2, var3 FROM tablename WHERE var_a = '$var_a' AND var_b = '$var_b' AND ( ( var1 = '$var1' AND var2 = '$var2' ) OR ( var1 = '$var2' AND var2 = '$var1' ) )"; This ...
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How to retrieve stored procedures from raw data

I have all the raw data from a database that I can't access through the mysql program anymore. I was able to get the tables by copying the .frm files over to the new installation of mysql, but I don't ...
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Synchronize part of the tables to use offline (no internet use) then sync back to server

I read some synchronization post but seems not suit my case. As I will sometimes go travelling locally and other country which I may have no access to internet then I could not even get the data in my ...
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Moving datadir OK start, but socket error for mysql client

I'm trying to move my MySQL datadir from /var/lib/mysql over to /home/mysql (an ssd drive as I'm having iowait issues on /var/lib/mysql when MySQL is running on that drive). The OS is CentOS 5.6 ...