MySQL : Open-Source, Relational Database Management System

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Mysql speed issues with SHOW COLUMNS or SHOW FIELDS

To avoid making code changes every time we have a database change, we just use the SHOW FIELDS (Alias of SHOW COLUMNS) to get all of the columns for Inserts. We call this multiple times for multiple ...
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12 views

Schema check or “DATE as separate table”

I'm dusting of my SQL, and would love to know if I've got my mental ER-diagram right. http://sqlfiddle.com/#!2/c5c59 Basically, I've got 10-15 different datasets (actividades) from several locations ...
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7 views

how to sync local mysql database and live server database?

my plan is to store data in my local mysql database and after a time intervel it will update my live mysql database remotely. Is it possible? i'm planing a inventory management script in php mysql. ...
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10 views

Infinite loop in MySQL when connecting to database

I am running xampp on Windows - Apache and MySQL start fine, but when I try to go to the directory where I have my example app, it loops infinitely waiting for localhost: The log shows: 2014-08-22 ...
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2answers
31 views

How to break table into two without losing performance?

According to http://stackoverflow.com/a/174047/14731, splitting away infrequently-needed columns frees up the cache allowing faster retrieval of the commonly-used columns. I've got a table whose ...
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9 views

Multi-Column Full Text Search Going Very Slow

I have a full text index on a table articles for the columns content, title and keywords When doing the search on each of the columns, like so select count(1) from articles where ...
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13 views

Combining 2queries: One filtered Users on Role, One Select users with only one specific role

First query: Selects All users with specific rid ( 3 or 4 or 19 or ...). SELECT u.uid AS uid, u.name AS name, fn.field_full_name_value AS field_full_name_value FROM users u LEFT OUTER ...
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1answer
37 views

Huge differences of performance of MySQL in two servers

We have a MySQL server installed in two different machines, a testing server and a production server, both windows, which is used by a web application. The problem is that there are HUGE performance ...
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1answer
24 views

Revoke write privileges vs setting database to readonly

I am planning to do a database migration to a new server. During the transition stage, I do not want Apache user to be able to write anything to the database. I have two options. Revoke write ...
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1answer
45 views

What makes yum difficult with RAID [on hold]

I as working with someone on a redhat server using RAID 10 with MySQL, and they mentioned it is hard to use yum when having a raid setup. Is this true? If so, what actually makes it 'difficult'?
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2answers
30 views

Difference between On Delete Cascade & On Update Cascade in mysql

I have two tables in MySQL database- parent, child. I'm trying to add foreign key references to my child table based on the parent table. Is there any significant difference between ON UPDATE CASCADE ...
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37 views

What is the Difference between SQL Server and MySQL? [on hold]

What is the Difference between SQL Server and MySQL 1) In technically and non-technically. 2)in business point view (ex: if i have new project to do. How i know which database is better to choose ...
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33 views

MySQL configuration to connect to multiple local applications

I've installed FreeRADIUS, MySQL and FreeRADIUS management (a web-based app) on the same machine, with both FreeRADIUS and FreeRADIUS management using same user to connect MySQL. My problem is when I ...
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2answers
30 views

Copying datadir directory enough for backing up a database with InnoDB tables?

I have an innodb table with 80 million rows and it's extremely slow with mysqldump so I'm thinking of copying the datadir directory for a backup / transfer. I used to copy database with only MyISAM ...
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10 views

If I were to peak under the hood, how does MySQL's GET_LOCK function work?

I am curious about how MySQL's GET_LOCK function actually works. I understand what it means when I ask for a lock, and what the potential return values are. But I want to get a better understanding ...
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14 views

MySQL Memory & max_connections Performance Tuning

So, our site runs WordPress and in the past few days we have been getting tons of spam comments etc. I believe that we are becoming the victims of some kind of bot army that has been crashing our ...
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2answers
38 views

average record hourly

I have one table, here is the schema CREATE TABLE `table_200901` ( `id` int(11) NOT NULL AUTO_INCREMENT, `carType` bigint(20) DEFAULT NULL, `dateTime` datetime DEFAULT NULL, `distance` ...
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1answer
27 views

Rolling count of total transactions over time

I need to get a set of total transactions over time on a weekly interval. Essentially I need a total-transactions-to-date column. When I group by WEEK(Date) I get the amount of transactions for that ...
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2answers
21 views

Best way to store few rows of data every minute without creating 1440 columns a day?

I will be calling a server that returns some JSON data every minute. The values are along the lines of Value, Currency, DateTime, and maybe 1 or 2 more values. What is the best way to keep save these ...
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1answer
30 views

Why does mysql treat “<” like it was “<=”?

I've tried the following command: SELECT * FROM `mi_schedule` WHERE `day`<=(DATE_ADD(NOW(),INTERVAL 7 DAY)) AND `day`>=NOW() Got 8 rows. Then I changed the <= to <, and nothing changed, ...
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31 views

How to measure bandwidth requirements for MySQL, Postgres, …?

TLTR: how to configure MySQL/Postgres to get a fair measurement of the I/O requirments for analytical queries? Hello, for certain database and especially database hardware experiments for want to ...
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1answer
14 views

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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1answer
25 views

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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23 views

Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL 5.1.73 database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. ...
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1answer
11 views

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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21 views

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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1answer
18 views

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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1answer
17 views

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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7 views

How to make MySQL log to 2 seperate remote servers? [duplicate]

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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1answer
15 views

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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13 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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8 views

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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4answers
100 views

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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1answer
29 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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1answer
35 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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1answer
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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1answer
19 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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1answer
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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1answer
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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1answer
12 views

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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21 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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1answer
19 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
16 views

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 ...
0
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1answer
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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28 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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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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8 views

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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1answer
12 views

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). ...