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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4
votes
2answers
907 views

Recommendation for mySQL table structure (no code)

I need some advice on how to layout the tables for a MySQL database. I will first describe what I am trying to do: I have a table for users. (This covers basic info for now) A user will select a ...
0
votes
0answers
517 views

Optimizing “Removing duplicates” thread state

I'm trying to hunt down MySQL variables/settings and metrics relevant to the "Removing duplicates" thread state. Here's a snippet from show full processlist. Id User Host db Command ...
0
votes
1answer
149 views

Why does copied MySQL database have different data than source?

I am trying to migrate database A to database B. I have tried various methods for this, including... Using Navicat, do Tools > Data Transfer, copying structure and data from A to B Using Navicat, ...
1
vote
2answers
4k views

Is it better to use AUTOCOMMIT = 0

Is it better to use (for perfomance tuning) AUTOCOMMIT = 0 before bulk inserts of data in MySQL, if the insert query looks like INSERT INTO SomeTable (column1, column2) VALUES ...
4
votes
2answers
4k views

Partitioning and freeing disk space

I am running MySql innodb with innodb_file_per_table. As a daily script, I would like to create a new partition for a set of tables, as well as delete yesterday's partitions. What command would need ...
3
votes
1answer
1k views

skip columns while using LOAD command mysql

I have a csv file having 5 columns and i want to load only one out of that, is there a way i can do it. I want to use LOAD statement of MySQL 5.5 Any pointers are welcomed, help would be much ...
0
votes
0answers
73 views

Procedure after commit

I have an application which periodically will insert large amounts of data, from that data I build a few materialized views (well emulate by creating a table from a view and replacing it with the ...
1
vote
0answers
701 views

How to sync mysql remote database daily ?

I have a database that contains orders , products ..etc. I have another system that generates reports based on this database. Due to heavy load i want to separate those systems Where i have the master ...
0
votes
2answers
275 views

Partitioning MySQL for “expired” transactions to improve performance

I am dealing with an existing application that uses the database as a sort of transaction log in several cases, for example orders or payments. These tables are large (20 - 60 million rows) and poorly ...
1
vote
3answers
5k views

How do I use subquery on the same table in MySQL?

I have a query like this which takes a really long time to run. The table is around 4 million rows. DELETE FROM TABLE WHERE value_was IS NULL OR value_was <= value_now; I'm hoping I could ...
1
vote
1answer
234 views

Mysql: Schema/Query Performance Approach for aggregated mailbox folders

I am about to code a messaging system where users can write messages to other users. User can create custom inbox folders for sorting the messages they receive, however, every user has 2 main inboxes: ...
3
votes
2answers
3k views

InnoDB tablespace critical

Could the error shown on the screenshot be the reason why my site is very slow? If so, I really need help to fix it since I am far from being an engineer!
0
votes
1answer
35 views

InnoDB Tablespace critical error in great need of a fix [duplicate]

Link to screenshot : http://www.nouvellesduquartier.com/i/1/p/Munin_%20Critical_MySql_InnoDB_.JPG Question: Could the error shown on the screenshot be the reason why my site is very slow?
3
votes
3answers
150 views

How can I improve this query?

About a year back I introduced a query which returns a sort of "Customers Also Purchased" data-set. At the time it ran reasonably fast however, as of late it's become very slow, sometimes taking up to ...
0
votes
0answers
215 views

SQL Access Denied - GRANT solutions fail

I've been searching for the solution for quite a while now, however, all the solutions involved another SQL code which would also be denied. I use PHPMyAdmin from 000Webhost, and when I try to run ...
2
votes
1answer
546 views

datetime vs timestamp in mysql 5.5

What is the difference between datetime and timestamp in MySQL with respect to data being inserted from different timezones? Does anyone have any clues on this? I have a situation where I am trying ...
1
vote
1answer
615 views

Unable to use mysql_upgrade:

I updated mysql recently and found problem related to privileges and backup. When I am using mysql_upgrade command it says- mysqlcheck: Got error: 1064: You have an error in your SQL syntax; check ...
0
votes
1answer
138 views

Two identical MySQL tables, one not using indexes

I have one MySQL Server (5.0.37) on a Linux Server that have many databases. Some of them (12) have each an identical table to log sensors data. Schema of one table CREATE TABLE `measuresHistory` ( ...
-1
votes
1answer
1k views

Having too many connection problem

We have an magento store and having 9K products and 2 store views the trouble is we are getting too many conection error while the site is in normal loads. 1) We have 100 connectoin open in mysql. 2) ...
1
vote
1answer
661 views

Stored procedure and prepared statements

I have 2 stored procedures: CREATE PROCEDURE `GetEntryCount`(param_Criteria VARCHAR(500)) BEGIN IF (param_CRITERIA <> "") THEN SET @QUERY1 = concat('SELECT user_name,count(*) as count ...
4
votes
1answer
6k views

Reloading MySQL my.cnf changes

Do you have to restart MySQL to edit changes? Or can you edit them on the fly and restart MySQL or make the changes inside MySQL? This server runs 100s of website that are active and I don't really ...
3
votes
1answer
137 views

How to share resources among accounts?

Using google doc, I am able to share my documents with others. I wonder how they implement it underlying in terms of DB design? The simplest way I imagine is to use a joining table which keeps a ...
1
vote
1answer
173 views

InnoDB Failure of some kind

I have MySQL 5.5 installed. I tried to install Joolma but it failed. I went into their sql and replace EGNINE=InnoDB with MyISAM and the install worked. InnoDB is listed under SHOW ENGINES; Any idea ...
0
votes
1answer
50 views

Creating database/tables in SequelPro (or MySQL) from External FTP Server

I just started getting a backup file (*.7z) from the folks that run our database once a week. They're sending it to me through an FTP server (I use FileZilla) -- but the file is pretty huge: 5.8 ...
0
votes
1answer
96 views

Am I overengineering MySQL?

On my project, I have to make difference between registered users, and simple visitors. Both of them can set their own properites, specified in accounts and visitors table. I identify them by cookie, ...
0
votes
0answers
661 views

MySQL is running but not working [closed]

In an attempt to tune MySQL to make it work with a recent installation of Drupal I had to modify the MySQL settings on my server. After modifying the configuration file for MySQL (/etc/my.cnf) MySQL ...
2
votes
1answer
643 views

Repair with 1 thread

Why would MySQL be using Repair with 1 thread to rebuild the indexes on a table (1 primary key, 2 billion rows) when I have myisam_repair_threads set to 4?
2
votes
1answer
3k views

Dealing with empty strings while loading a table from a CSV

I am trying to load a CSV file into a table. The CSV file contains some empty strings for example: 1,2,,4 I want to load the empty field as null. One way I know is to use \N i.e: 1,2,\N,4 but it ...
0
votes
1answer
41 views

Mysql reliable with 1000 new entries / minute?

I have been developing an application that in the WORST case writes 1000 entries each minute into a database for over a year... I wanted to use Mysql as DB, but I have read that with high ...
0
votes
1answer
2k views

Large INSERTs performance optimization

I have 15 Amazon AWS EC2 t1.micro instances which simultaneously populate Amazon RDS MySQL d2.m2.xlarge database with data using large INSERTs (40000 rows in query). The queries are send ...
2
votes
2answers
710 views

How to perform ETL from RDBMS to Neo4j

I have a mature 50+ tables web application based on mySQL. In order to do some advanced data mining I want to use Neo4j and the goodnes of cypher. However I'm having a hard time migrating my data from ...
2
votes
1answer
2k views

Ubnutu/MySQL - Error “Unable to locate package innotop”

I am using Ubuntu 12.04.2 LTS, with MySQL 5.5.29. Im trying to install innotop for database monitoring, but getting an error "Unable to locate package innotop" root@server1:~# apt-get install ...
2
votes
1answer
1k views

Why is MySQL order by performance poor within a single partition of a partitioned table?

I have to store some sequence numbered data in MySQL. I have about 300,000 data items per day for about a 10 year span. Let's say the table structure is just sequence number (a big int) and data (a ...
1
vote
2answers
947 views

Is it okay to rename the MySQL data files (FRM) manually?

Like everyone, I realized the case sensitivity issues in MySQL of late. I wanted to convert my upper case table names to lower case using this solution but I forgot to do Step 1 and completed the ...
1
vote
1answer
424 views

Drop database locked the server

I tried to drop one of the databases on the server. That locked the entire server up so I stopped the mysql process via the console. I restarted the server, started mysql and now it seems hanged on: ...
4
votes
3answers
13k views

mysql replication successful but slave not replicating

I have created a mysql master-slave configuration and things look fine . the " show master status;" on slave doesnt show any error . this is the output Slave_IO_State: Waiting for master to send ...
2
votes
1answer
500 views

How to ensure that date-range queries involving multiple time zones are sargable

I am building a web analytics application for search engine traffic only. You can see some screenshots here: http://myhappyanalytics.com/ It works similar to Google Analytics but it only saves and ...
1
vote
1answer
3k views

passing --single-transaction in mysqldump command line tool

I'm using MySQL GUI tool to backup my innodb database and I use the option '--single-transaction' to get a consistent copy as backup. I have however, noticed that if I backup using command line ...
0
votes
1answer
310 views

Order of where clause evaluation

If I have a MySQL table which has content from the last 3 months I actually do the following: SELECT SQL_BUFFER_RESULT SQL_CACHE count(id) cnt FROM `mDelivered` where _campaign = 2 and `session` = ...
1
vote
1answer
173 views

How to “swap” out production tables

I have a MySQL table that holds a few thousand records which go out of date very quickly. A few times a day we run a slow process which needs to pull data from multiple sources and re-populate the ...
0
votes
1answer
4k views

In place upgrade from MySQL 5.5 to 5.6.11 removes all users from user table

On Windows, I upgraded from 5.1 to 5.5 no problem. Copied my 5.1 data folder into my 5.5 instance Started mysqld skipping grants Ran mysql_upgrade All good, but going from 5.5 to 5.6: Copied ...
0
votes
2answers
245 views

Using a keywords table with multiple other tables

Using MySQL I need help determining how to model a Keywords table to three different tables (Products, Certifications, and Exams) - I have included my model which is using what I refer to as ...
2
votes
1answer
852 views

How to add additional tables/fields into a query with multiple inner joins?

Given this query (many thanks to RolandoMySQLDBA from question Select records that do not have associations outside a certain list), how do I add other fields from other tables into my result? SELECT ...
1
vote
1answer
496 views

Select records that do not have associations outside a certain list

I have a mySQL table of nodes and each node can be associated with many categories. I have a list of category ids that are acceptable (498, 499). I want to select only nodes who do not have ...
0
votes
1answer
509 views

How to get rows where count() is null?

This is my SQL request : SELECT COUNT( b0_.id ) AS sclr0, d1_.codeLieu AS codeLieu1, d1_.nomLieu AS nomLieu2, d1_.lngLieu AS lngLieu3, d1_.latLieu AS latLieu4, m2_.libelleMention AS ...
0
votes
1answer
2k views

Synchronise data from one table to another & vice-versa using triggers

We are migrating from one database structure to another - very slowly. The system is MySQL. There are two databases. For example's sake, we will call the databases old_db and new_db. Both databases ...
0
votes
1answer
1k views

Are there any disadvantages to partitioning on financial year?

Our current set up has one table per financial year (May 1- April 30). Each table has approx 1.5 million rows. We have about 8 years of data, and will obviously be adding each year. The majority of ...
1
vote
1answer
2k views

SQL Server-MySQL master-master replication

We are looking into setting up a master-master replicated MSSQL database and I am interested to hear of any potential pitfalls that we may run into along the way and generally any advice that you ...
0
votes
0answers
31 views

Should store procedures be cached?

Should store procedures be cached in MySQL? If so, How long it is stay in cache? In my case, When I call one stored procedure first time, it is giving me results in 1 second, after that it gives me ...
0
votes
2answers
1k views

How to use and optimize subquery on 100 million rows

What I'm trying to do is running a job on more than 100 million domains which haven't processed before. I have two tables, "domain" and "domain_setting", on every batch (10.000 domains per batch) I'm ...