All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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2answers
2k views

mysql trigger on update with insert statement

I am trying to create a simple trigger which is handled on update operations. The trigger is checking before update if a record of an update exists, then if not it is created. DELIMITER ;; CREATE ...
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1answer
543 views

MySQL not allowing text columns?

I'm using MySQL 5.5.27. I currently have a BLOB column, that I want to convert to text to allow fulltext searching. The ALTER TABLE command to create a text column is successful, but the ALTER TABLE ...
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3answers
17k views

How to migrate SQL Server to MySQL

I'm trying to migrate a SQL Server db to MySQL, and I'm having a tough time. I've tried: MySQLWorkbench -- migration tool fails because my login only shows views in SQL Server, not the tables ...
3
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2answers
288 views

mysql second slave not syncing while first slave works fine

I have a master (m) - slave (s1) setup using mysql 5.1.45 When I try to add a second slave (s2) the slave lags behind and never catches up on the sync. Even after having synced the s2 with the whole ...
1
vote
1answer
1k views

Mysqldump from the Amazon RDS

I have a Mysql database deployed on Amazon web services RDS. I am running a crontab which runs mysqldump command. The problem is it freezes the rds instance and my website will be down for more then ...
1
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1answer
2k views

Scheduled event did not start when expected

I have created one event schedule which looks like this: mysql> show create event event1 -> ; ...
7
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1answer
17k views

On duplicate key do nothing

I am inserting into the following table using LuaSQL with PtokaX API. CREATE TABLE `requests` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `ctg` VARCHAR(15) NOT NULL, `msg` ...
1
vote
1answer
250 views

Best way to set up database tables

I have 1 user table and want to associate it with multiple other tables depends on if user have added such information (modules) and want to know what is the best way to do it. main table ...
0
votes
1answer
333 views

Extracting Multiple Values from Single Field

I'm an SQL beginner and I'm having trouble searching correctly for the answer to this question, although I'm sure that it's been asked before. I have an column in an SQL table that looks like this: ...
1
vote
1answer
238 views

MySQL: parallel restores at same time from backup files?

Slightly related to this question, but for MySQL: Would it be possible/wise to execute 2 parallel restores from a single backup? Is it possible/wise to do a parallel restore of two independent ...
3
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4answers
31k views

MySQL - ERROR 1045 (28000): Access denied for user

I just installed a fresh copy of Ubuntu 10.04.2 LTS on a new machine. I logged into MySQL as root: david@server1:~$ mysql -u root -p123 I created a new user called repl. I left host blank, so the ...
1
vote
1answer
291 views

For a InnoDB only DB, which of these elements can be removed?

So, I'm trying to set up a Drupal 7 my.conf file that's combining best practices from various performance blogs. I'm realizing though that some of them are older than others, and many aren't assuming ...
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2answers
2k views

How can I migrate a sybase database to mysql? [closed]

I've been tasked with migrating a fairly complex legacy Sybase database into a MySQL database and I have no idea where to start. I can't use any off the shelf software, so I'm going to have to write ...
2
votes
1answer
552 views

Drupal 7 Uses InnoDB, so do I need other configs?

If I'm optimizing a database that will be delivering multiple Drupal 7 websites, all using InnoDB, do I need to worry about [myisamchk] & [isamchk] sections, or can I just worry about the stuff ...
0
votes
1answer
489 views

MySQL inserts/deletes slowing down after a while after Start/Reboot

The Setup here is: OS: Ubuntu 12.04 (1 Core and 1.75 GB of RAMO) MySQL Version: 5.5 There are about 8 to 9 tables in the database. On initially starting mysql the queries are fast at around 0.05 - ...
3
votes
2answers
403 views

Should I use a compound or surrogate PK in a many-to-many table?

I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` VARCHAR(255) NULL DEFAULT NULL, PRIMARY KEY (`isbn`) ) COMMENT 'Books used at this ...
3
votes
1answer
739 views

How this simple Stored Procedure ended up in Deadlock

Thanks for all and this forum is really helpful. After few minutes of system running we get “Try restarting the transaction.” And its end up in deadlock. We use MySQL 5.5.28 and the Java code ...
1
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1answer
81 views

Mysql performance for a nullable unique id column in a large table that references a record in another table

We have a large table of contacts (8 million records) that we promote to with mailings. When these people register we store them in a different members table. But we want to go back and update the ...
1
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1answer
1k views

MySQL subqueries that use range based on values of main queries don't use indices properly

I think I've isolated a problem that has been affecting many of my queries lately. And would like some help to figure out a solution for this. Ok so my findings are that a normal query that runs very ...
1
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1answer
940 views

Do I need client certs for mysql ssl replication?

I'm setting up mysql replication using SSL, and have found two different guides. The first one creates both client and server certs, while the second one only creates server certs. I don't know ...
0
votes
1answer
498 views

optimize big sql query

My query has to return a statistics for example for march containing productname and price and its sidedishes (1:n relation) with the right price of each sidedish and the right tax for each sidedish ...
0
votes
1answer
118 views

Is it possible to have extra tables in a Slave with MySQL Replication

As my title mention I have a Master and a Slave database. Master if for operations data and my slave mainly for reporting stuff. The issue is that I need to create extra tables on reporting that ...
4
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2answers
326 views

Are there implicit indexes in InnoDB like MyISAM?

If you have (id, a, b, c, d) table with primary key (id) and another key (a, b, c), in MyISAM that means that you also have the following implicit keys: (a) (a, b) (a, b, c, id) Is this valid for ...
2
votes
1answer
1k views

Optimize query execution based on two datetime columns

I've been struggling all day long against this. We have a very busy database (still on development) and we have records being inserted very frequently. The record logs have a start time and a end ...
0
votes
1answer
203 views

how to use mysql to delete only the first ten table records?

I'm currently using php and mysql together. What I want to try is if I have ten "stable" records for the database and in the same .php file I have some text boxes so I can type in then what I typed ...
0
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1answer
94 views

Speed efficient query for membership first joined, latest category from membership table (min, max)

I have the following table representing membership information: CREATE TABLE IF NOT EXISTS `membership` ( `id` int(11) NOT NULL AUTO_INCREMENT, `organisation_id` int(11) NOT NULL, ...
1
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1answer
727 views

MySQL my.cnf won't take any effect

Update 7 As DerekDowney suggested, I tried to use [mysqld] init_connect=SET NAMES 'utf8' But I could not get the desired result. My client side java programme still says both session and global ...
0
votes
0answers
61 views

InnoDB best index practises

I have an InnoDB table with around ~3.7m rows in it. Here are my current indexes: ...
5
votes
1answer
446 views

How to write this self join based on three columns

Hello there I have a following table ------------------------------------------ | id | language | parentid | no_daughter | ------------------------------------------ | 1 | 1 | 0 | ...
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0answers
118 views

MySQL Partitions

I've done a lot of work with MySQL but generally on a much smaller scale than this, so please excuse my ignorance. We've got an InnoDB table which is currently storing ~3.5 million rows, which I know ...
0
votes
1answer
535 views

Mysql - Problem speed of access on query (Low latency query sometime)

My web application is real time site that need a speed of access on every query (SELECT, UPDATE, INSERT) that must less than 200ms Because one of my php script task is query (SELECT, UPDATE, INSERT) ...
-1
votes
1answer
96 views

Optimization of a select statement

I'm using MySQL and have a table user_data like this: user_id int(10) unsigned reg_date int(10) unsigned carrier char(1) The reg_data is the unix timestamp of the ...
1
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1answer
547 views

Best way to query huge data

First let me describe my case: I need to store around 200extra detail of each user. I am using wordpress. Now there is a default function to save data associated with user. But i am not sure what ...
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0answers
390 views

MySQL 5.1.67 - Replication failure Mysql, Master Log Truncated or corrupted

I have run into some issues with replication After an in-place upgrade of mySQL from 5.0.77 -> 5.1.67 rel 14.4 Percona replication between a master and multiple slaves is causing issues. slaves are ...
4
votes
2answers
2k views

Index before or after bulk load using load infile?

I have a database with over 1B rows and two columns that are indexed (in addition to the PK). Is it better to have the index pre-defined in the table before the load infile or better to index after ...
1
vote
1answer
3k views

Cascading Inserts in MySql

I have a users table that has a one to one relationship to a user_preferences table (primary foreign key user_id). When a new row is added to the users table (new id added), is there a way to setup ...
0
votes
1answer
403 views

MySQL Slave Lagging Almost Daily -Ver 5.5.17 ( Master & Slave )

I am observing this lag in a continuous manner. Investigating in the bin log events, i found the following information. Slave executing the relay Logs slowly. 1. Changing the Innodb File Format ...
3
votes
2answers
10k views

How do I fix the definer problem The user specified as a definer ('fred'@'192.168.0.%') does not exist

I dumped an existing database from my web site into a new MySQL setup on my laptop. Everything works except pages that use a view, when the error message above appears. There is only one view on the ...
2
votes
2answers
561 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';" ...
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2answers
297 views

How to migrate data from SQL database to MySQL including flat files?

one of my friend has asked some asp developer to make online application where user can upload files also. jpg, doc, pdf and all these files are saved in SQL database as flat file. Now my friend asked ...
1
vote
1answer
270 views

Unique index on 2 columns in mysql

I have one table in mysql named 'UserFriends' where I am updating my websites user's friends details. here is the schema of the table (UserFriends) id int, Userid int, friendid int, createdate ...
1
vote
2answers
6k views

loading a csv file which is on local system in to Mysql DB which is on remote server

Can we directly load a CSV file ( which is on the local system) on MYSQL DB ( which is installed on the Remote server ) ? 'load data infile into table name' command can only be used for loading in ...
0
votes
3answers
2k views

MySQL - What exactly does smallint(2) permit? [duplicate]

Sorry for the really simple question, but I can't figure it out. When I set up my schema, I set up my primary key to use a field of type smallint(2). The thought behind it was that the field should ...
1
vote
1answer
289 views

Linux 32b MySQL periodically crashing with signal 11 and OOM errors [closed]

I have a MySQL DB with mostly InnoDB tables that I'm fairly certain isn't tuned properly based on what's happening, but I don't have enough know how to pinpoint what to change. The server is a 8G 32b ...
1
vote
1answer
2k views

SELECT every second row without auto_increment

How can I select every second row in MySQL, without using any data of the table or some auto_increment? Something like SELECT EVERY SECOND ROW FROM `table`; Thank you!
3
votes
1answer
2k views

MySQL - run SELECT statement on another server without defining the table structure

In MySQL I can query information on another server using federated tables, as long as I've defined the same table structure locally. In MS SQL Server, however, I can run any SQL statement against a ...
3
votes
2answers
1k views

Compare two MySQL dump files

I am trying to compare two MySQL dump files. One was made from a fresh install of a web application and the other is a dump from the same web application that has been upgraded from a previous version ...
2
votes
2answers
3k views

SQL Server to MySQL migration - how can I remove UCS-2 surrogate pairs in SQL Server?

I have been tasked with migrating a SQL Server 2005 database to MySQL 5.6 (these are both database servers runnig locally) and would really appreciate some help. -------Edit - Answered------- This ...
3
votes
0answers
3k views

Achieve PostgreSQL hstore functionality in MySQL

Please suggest any MySQL 5.5+ Engine that can support collection of key-value pairs be stored in any column of a table. I don't know if this feature is available out of the box in MySQL like ...
1
vote
2answers
333 views

Unique indexed column in where clause and mysql execution after finding first row

Suppose in a table there are 2 columns: login and password login is indexed as unique index, password not indexed. query: SELECT * FROM mytable WHERE login = 'Jhon' query: SELECT * FROM mytable ...