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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759 views

Why Percona MySQL is crashing again and again

We have Percona MySQL Cluster running with three nodes on CentOS. Server : Percona-XtraDB-Cluster-server-56-5.6.19-25.6.824.el6.x86_64 One node is crashing repeatedly. Thread pointer: 0x18910ba30 ...
2
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1answer
853 views

Summarize from unlimited level depth parent-child in mysql

I have 2 table master coa and coa transaction in MySQL like this, master : id | coa | id_parent | ----+------+-----------+ 1 | 1 | NULL | 2 | 11 | 1 | 3 | 111 | 2 ...
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1answer
768 views

MySQL cluster: Failover between data node

Today, I do some expirements for understanding MySQL cluster better. MySQL cluster works fine: ndb_mgm> show Connected to Management Server at: localhost:1186 Cluster Configuration [ndbd(NDB)]...
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2answers
1k views

Is it safe to copy DB files directly from an LVM snapshot?

I saw two different approaches for backing up database with LVM snapshot. This article suggests spawning another MySQL instance to do an SQL dump. MYSQL Performance Blog suggests that it is safe to ...
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0answers
51 views

MySQL Event that process large data volume randomly errors

I have a MySQL event that uses a cursor to loop through a large volume of user data. Randomly, and this has only recently started happening, I am getting:- 1 queries executed, 0 success, 1 errors, 0 ...
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1answer
15 views

Completely disable all support for a certain CHAR SET in MySQL?

Is it possible to completely disallow certain charsets in MySQL and force an error and/or force everything into the server's chosen default charset?
-1
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1answer
346 views

Using C# need to drop all tables in mySQL database beginning with prefix

I have found this question answered but not specifically for C#. The answer seems to be to execute the following statements tailored to my specific database. However, I can't figure out how to use ...
0
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1answer
72 views

Query for which my.ini in use

Is it possible to query mysql server to know which configuration file is in use? Sometimes, my.cnf, my.ini. SHOW VARIABLES; -- does not have enough information here for my.ini path
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1answer
959 views

Change table from InnoDB to ARCHIVE in MySQL

I try change my table from InnoDB to ARCHIVE with SQL command: ALTER TABLE data_obook ENGINE = ARCHIVE; But it always show me only error: #1005 - Can't create table 'coincity.#sql-1350_8a' (errno: ...
0
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1answer
58 views

mysql auto_increment [duplicate]

I deleted 11 rows and I want the auto increment id values to reset to 6,7,8,9 … How can I achieve that without using the update statement each row one at a time. I want to find out if there is a way ...
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2answers
657 views

Messaging Database - How to handle multiple recipients

So I am trying to develop a relational database (I'm using MySQL, planning on a Java front end) where I have 3 tables (People, where I store names and relevant personal information... and Messages (...
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1answer
2k views

What's the maximum number of tables that can be referenced in a query in MySQL?

In the days of SQL Server 2000 and 2005, the maximum number of tables in a query was 256. Does MySQL have a similar limitation? I know that such query of such size means that either there's ...
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0answers
414 views

Updating +150,000 rows using .sql file causes ERROR 2013 Lost connection to MySQL server during query

I am using ubuntu 12.04. I have a .sql file that is around 5 megabytes. When I use the command: mysql -u -p -v database query.sql The server prints out the content of the file (because of --verbose) ...
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1answer
1k views

MySQL: Use Sysbench on Windows

Sysbench is a tool to analyze the MySQL performance. I downloaded it and extracted but there is no executable file. Files having extensions like .sh or .c or .h are available. I gone through the ...
8
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3answers
3k views

InnoDB import performance

I'm struggling with bulk importing a quite big InnoDB-Table consisting of roughly 10 Million rows (or 7GB) (which for me is the biggest table I've worked with so far). I did some research how to ...
0
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1answer
117 views

How does a tagging article database look like?

I have a article website and each article has some tags. How should be my database structure? This is my article table (article): article_id (key) | article_content | article_title | ...
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1answer
63 views

Mysql dump with View dependent on user

I use simple mysqldump with only parameters are login and db details. No option of anykind is set. Now, when I recieve the dump file, it export the view in steps (I am sure you all know it, but just ...
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2answers
747 views

How do I group the data in the following format?

Using the following table OrderDate OrderID [dates] [id] I want to display in the following format : quater name nooforders q1 10 q2 10 q3 20 I ...
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1answer
90 views

MySQL root changed password went wrong

So basically this is what I did: mysql> use mysql; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database ...
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0answers
116 views

Index on fields with a function

I have a log table. It logs visitor data (time of visit, browser, window size ...). I want to create reports. I use a query like this (MySQL): SELECT COUNT(*) as raw_views ... FROM logs WHERE ...
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2answers
10k views

MySQL tuning (my.cnf) for very large tables and ad hoc queries [duplicate]

We are an email marketing company and recently switched our setup to MySQL. We need to configure mysql (my.cnf) for extreme performance. We have tried to configure my.cnf but heavy queries can get ...
2
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2answers
71 views

Give every user 3 default 'bookmark' entries

I've got a table users and a table bookmarks. The table bookmarks obviously contains pages the user wants easy access too. But, there's a new requirement now: every user gets 3 unmutable bookmarks. ...
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2answers
670 views

DB Design Payments Table

I'm working on a Desktop application that uses a DB to store information i.e (customers, houses, proprietors, payments). So the application must accept payments from customers to company, company to ...
6
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1answer
4k views

What is the differnent between transaction log and redo log in MySQL

I have read about MySQL. In my opinion, I see two log type is very similar. MySQL save how and when data is changed in log. Information is used for recovery of MySQL. I am confusing the function of ...
2
votes
1answer
2k views

Auto_increment value needs to be set as S1

Hi I need to set auto increment for a table as S1. I tried by altering the table and also by creating by new table I am aware how to set auto_increment but when i try to set auto increment as S1 i am ...
0
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1answer
967 views

MySQL 5.1.x: Performance improvement in Enterprise edition Vs community edition

My application is running on MySQL 5.1.58 community edition. I tried to search enterprise edition of MySQL 5.1.X but only MySQL 5.6.X version of enterprise edition is available. Is it possible to ...
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7answers
33k views

Is it possible to mysqldump a subset of a database required to reproduce a query?

Background I would like to provide the subset of my database required to reproduce a select query. My goal is to make my computational workflow reproducible (as in reproducible research). Question ...
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4answers
510 views

How to Identify the user who issued MySQL Shutdown command

We have had several situations when our production MySQL server suddenly became unavailable. The error log just shows "Normal shutdown" followed by the typical shutdown messages. How can I determine ...
2
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1answer
3k views

Can I execute an external process via MySQL on table change?

When using triggers, if an update is done to a table then a trigger is executed. This is very convenient. But what I would need is to execute an external script. Is it possible to configure MySQL ...
0
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1answer
88 views

Searching through ~1M slow

I've never had a database with this many rows, so I can new to keeping the search time to a minimum. I have a database table with 1.5M rows. The primary key is an auto-increment id. Then there is ...
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1answer
763 views

MYSQL will not start

I am getting the errors below when trying to start MYSQL. I've deleted both the ./ib_logfile0 and ./ib_logfile1 files and still no success. I'm assuming is has something to do with not being able to ...
2
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2answers
3k views

MySQL Workbench Alter Procedure

i have a problem with my workbench program. I use Mac Lion OS X and mysql workbench program. When i want to do any procedure to alter that doesn't work. Which is show to the procedure code i right ...
2
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1answer
231 views

Does READ UNCOMMITTED have the same effect as AUTOCOMMIT=1?

AFAIK running transactions as READ UNCOMMITTED means that there is no lock, so every change caused by a transaction is immediately visible to other transactions. Is it correct to assume that this is ...
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1answer
250 views

Can I estimate the row count of a large mysql table using the disk space?

Sysadmin here (not a developer by trade), so go easy please ;) I have a mysql table, on a linux server that uses innodb_file_per_table. When I try to do select count(foo) from table; It doesn't ...
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1answer
198 views

MySQL thread states when changing an in-memory temporary table to disk-based

In High Performance MySQL (3rd edition) they state that: You can't tell whether a table was created in memory and then converted to on-disk or just created on-disk to begin with... What I was ...
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1answer
47 views

MySQL server performance plummets

Part of our software solution is responsible for processing files that get uploaded to us by our clients. We want to process them as quickly as we can. Our system is architected so that there's a ...
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0answers
59 views

How to optimize having bit_or?

Let's start with SQLFiddle http://www.sqlfiddle.com/#!2/64fc5/1 I have some urls and I am making some tasks (crons) related to them. Task can be successful or not. I want to try to do it only three ...
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1answer
69 views

Schema design - Reference slightly different data in different tables

I'm trying to design a schema for a MySQL database and got stuck on the following. My database stores documents which should have relations with blocks of content. create table document ( `id` ...
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1answer
4k views

Difference between count(*) and count(1) in mysql?

In MySql we can count the total number of records by using count(1) or count(*). Is there any technical difference between them?
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3answers
163 views

Find the user with closest taste of mine

I trying to write in SQL the following requirement: Each user can rate as much films as they like. (1= I don't like, 5=I love it) And the system should provide to the current user a list of films ...
0
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1answer
38 views

How to minimize the writes needed to update a counter field multiple times

I need to minimize the number of queries that are executed just for updating a counter field. One of my example counter fields is raised by 1 everytime a page is visited, I was wondering what could ...
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1answer
271 views

Different column for different conditions when joining

I am using MySQL database and in that two tables, relation is one to many. One table is product table, sample data: +----+----------+ | id | name | +----+----------+ | 1 | product1 | | 2 | ...
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1answer
1k views

Database design for mobile app

At first I would like to say hello to all of you, since it is my first post here on DB Administrators. I am writing an app which store drinks and their data. At the beginning it was storing all in ...
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1answer
46 views

MySQL Referential Integrity Issue

I'm having a lot of issues and don't really know where to look. I'm pretty sure it's a referential integrity issue and has something to do with the addition of the Professor table and the Foreign Key ...
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1answer
3k views

Inserting empty string on Windows MySQL doesn't use default value

Why inserting '' on a column with default integer value on MYSQL/WINDOWS produces ERROR 1366 (HY000): Incorrect integer value: '' for column 'id' at row 1 The query is: insert into test2 (id,test) ...
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0answers
58 views

Problems with foreign keys in a mysql database

I am trying to link both these tables with a foreign key. But I keep getting error message "ERROR 1452: Cannot add or update a child row: a foreign key constraint fails " the foreign key is pwalk_id ...
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1answer
69 views

Using MySQL Workbench, what is a good way to do development on an alternate server and copy changes to the main server?

This is a noobie question. I'm taking over a database project from someone who recently left the company and I'm looking for advice on how to do some development on a test platform before making ...
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0answers
127 views

How to make changes to MySQL database settings

I'm a real DBA newbie and have learnt everything in the last day, so need basic guidance on how to implement the recommendations from MySQLTuner (which i eventually managed to do!) >> ...
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3answers
19k views

Why can't this mysql user log in with password?

In phpmyadmin I created a user called "edward" with password and all privileges: Yet when I try to log in via phpmyadmin, it says "Cannot log in to the MySQL Server". When I try to log in on the ...
2
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1answer
385 views

Options to include with mysqldump when taking backup of hybrid databases

I'm planning on taking backups of all MySQL databases on a remote production server. The combined database size is around 2 GB. Most of the tables are InnoDB ~1.8 GB and the rest are MyISAM. Now I've ...