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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7
votes
2answers
6k views

Is it bad to create many mysql temporary tables simultaneously?

I need to make heavy statistical analysis to deliver some data to users. Currently, I catch the data from mysql and process them via PHP arrays. However, mysql temporary tables are quite better (...
4
votes
3answers
4k views

MySQL slow log configuration

Is there a way of making MySQL slow logs to start new log file every day ? At the moment its just a single large file, and have to grep lines for every day. It would be much more convenient to have ...
6
votes
1answer
858 views

Does MySQL still handle indexes in this way?

Dropping a duplicate index in MySQL was taking rather long, so while I was waiting I searched about it & found this post from 2006, talking about how MySQL handles ADD and DROP index. If a ...
4
votes
1answer
34k views

How do I select items from a table where a single column must contain two (or more) values?

I have a MySQL database table that references different words and their locations in documents. I want to return the IDs of documents that contain all of the words. Here is an example table. docid ...
1
vote
2answers
3k views

Stress test MySQL with queries captured with general log in MySQL

Is there any tool available which can do stress testing using the log file created by MySQL general log? After a lot of search on google I found few stress testing tools which only use some benchmarks ...
5
votes
1answer
710 views

“Site Offline” MySQL server failing to start and stop

I'm hosting a few sites on linode and have encountered a strange problem. For the last two years the site has been running perfectly fine, and now randomly all the websites on the server go to the "...
1
vote
1answer
5k views

ERROR 1114 (HY000) at line 6308 in file & The table user_analysis is full

There is a SAN mounted 1TB partition for Mysql backups in our server with version 5.0.45-log. From two days, im seeing the log entries ERROR 1114 (HY000) at line 6308 in file & The table ...
10
votes
2answers
14k views

What to set innodb_buffer_pool and why..?

I have 170GB of InnoDB index and Data. I have to readjust the innodb_buffer_pool size for better performance.The Max table size of a InnoDB table(Index+data) is 28GB. So what should be the optimal ...
17
votes
7answers
51k views

Need to migrate SQL Server to MySQL

I have a database on SQL Server 2008 on a Windows server and I want to move all of the data to a MySQL database on a Ubuntu server. I have tried using the SQL Server Import and Export Wizard with the ...
8
votes
1answer
6k views

Qcache_free_memory not full yet I get alot of Qcache_lowmem_prunes

I just started dabbling with the query cache for our CMS. Can anyone tell me (or at least give a good guess) why I get a lot of Qcache_lowmem_prunes when more than half of Qcache_free_memory is free? ...
4
votes
1answer
3k views

Proper tuning for 30GB InnoDB table on server with 48GB RAM

I have a 30GB 15M rows InnoDB MySQL 5.5.15 table. It is running on a server with many other MyISAM tables (300GB db). The system has 48GB RAM. Besides the default configurations, I've changed the ...
15
votes
2answers
2k views

What can we do in MySQL 5.0 Replication to address bandwidth concerns?

I am developing an application to run on the client PC (Win) which is configured with a MySQL server 5.1 instance that will act as read-only slave to the remote master. The remote master has dozens of ...
6
votes
1answer
6k views

Best solution for cross-datacenter MySQL master-slave replication

We are working on a new system architecture for our company. We have a HPC, which runs in our own data-center and we are planning our front-end and a fallback system on Amazon Web Service. System ...
4
votes
1answer
3k views

Mysql Memory table getting many locks

On my site I log every pageview (date, ip, referrer, page, etc) in a simple mysql table. This table has the following activity: 1 SELECT per minute 1 DELETE per minute no UPDATE queries Lots of ...
5
votes
2answers
6k views

When should I think about upgrading our RDS MySQL instance based on memory usage?

It seems like our DB server is doing garbage collection at a increasingly faster rate, which seem normal since it's growing. What's a good rule of thumb of when to switch to a bigger instance, I'm not ...
10
votes
3answers
13k views

Why does MySQL ignore the index even on force for this order by?

I run an EXPLAIN: mysql> explain select last_name from employees order by last_name; +----+-------------+-----------+------+---------------+------+---------+------+-------+----------------+ | ...
9
votes
3answers
15k views

How do you re-sync the Master MySQL DB with Slave DB changes if the Master goes offline?

MySQL Server 1 is running as Master. MySQL Server 2 is running as Slave. With both DBs online, they are in "perfect sync". If Slave goes offline, there's no problem if Master still online; they will ...
5
votes
1answer
849 views

Should I use a storage engine other than MyISAM to optimise these tables or should I get better disks?

There's a production database I'm working on, whose 4 largest tables contain between 4 million and 10 million rows each and about 15 fields each, with indexes on different field types (numbers, ...
4
votes
4answers
12k views

Optimized my.cnf for high-end and busy server

Curretly my main culprit of poor performance is MySQL and I'm not a DB savvy. So far, I've had little luck in optimizing mysql configs on my server, which has a Sandy Bridge processor with 16GB ram ...
6
votes
2answers
3k views

Insert-heavy InnoDB table won't use all my CPU

I have a packet log database, which is almost never queried. It just needs to be fast on inserts. I'm using InnoDB because I'd like to maintain ACID compliance, since even losing a single packet could ...
5
votes
3answers
8k views

Disable trigger for just one table

Is it possible to disable a trigger momentarily but for just one table. For example I have table, TableA with an on insert, update and delete trigger. I also have a table B with the same triggers but ...
4
votes
3answers
2k views

Log MySQL DB changing queries and users

For security reasons I need a server-side (running Debian 6.0 Squeeze) logging of all queries that may have changed the content of a MySQL DB (v. 5.1) and the user who issued it. I had to rule out ...
4
votes
2answers
9k views

MySQL Event does not run

i am running mysql 5.1.41 that came bundled with xampp on windows. the problem is that the event doesnt run automatically even when the event scheduler is ON. i have a table named ta_table using ...
2
votes
1answer
8k views

Any known issues upgrading from MySQL 5.1.73 to 5.6.21?

I am planning my MySQL DB ver5.1.73 running on a CentOS 6.5 machine to MySQL 5.6.21. I understand the basic procedure for this based on what I have read on StackOverflow, but I was curious if anyone ...
5
votes
2answers
1k views

Choosing MyISAM over InnoDB for these project requirements; and long term options

Sorry for the long post, but I had to give as much info as possible to make this very vague question more specific. My project's aim is to let users search a (huge) database of variety of products. ...
4
votes
2answers
3k views

Select rows where value of second column is not present in first column

I have this table structure: id1 id2 1 2 1 3 1 4 2 1 2 5 I need to build a query to select id2 where id1 is not in id2. For example if id1 = 1 then only id2=3 and id2=4. I tried ...
3
votes
2answers
2k views

How do I determine how much data is being written per day through insert, update and delete operations?

The longevity of SSDs is largely determined by the amount of bytes written by insert, update and delete operations. What is the best way to accurately determine how much data is being written by ...
2
votes
1answer
4k views

MySQL upgrade 5.0.88 to latest

Very interesting and informative blog.. I have a question - i have a requirement of upgrading from 5.0.88 to latest version.. Why should i upgrade? if so, which version should i consider? What ...
2
votes
1answer
5k views

MySQL service stops after trying to grant privileges to a user

I am using MySQL 5.6, I was trying to create a super user for specific database but I got ERROR 1396 (HY000): Operation CREATE USER failed for 'superuser'@'%' Then I thought maybe there is already ...
6
votes
4answers
9k views

MySQL gives “Out of Memory” error when inserting a large file. From where is this filesize limitation arising?

I'm using a MySQL database to store files. The table I'm using is structured as follows: +--------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default |...
5
votes
1answer
1k views

MySQL Replication : 1 Slave / Multiple Masters

I have a web app with 2 web servers and 2 database servers. The DBs are setup for multimaster replication. (this is the primary environment) I also have the exact same setup on a different location ...
5
votes
1answer
909 views

will replication from 5.5.20 to 5.0.XX server work?

I gave two machines which run on two entire different versions of MySQL server. I want to do the replication from 5.5.20 to 5.0 server. Will that be possible? Because I remember when I transferred ...
4
votes
1answer
1k views

FULLTEXT index ignored in BOOLEAN MODE with 'number of words' conditional

fulltext match is ignoring its index when I add a number of words conditional for its boolean mode. The selects are as follows: explain select * from seeds WHERE MATCH(text) AGAINST ("mount ...
4
votes
1answer
5k views

Mysql Master-Master Replication Topologies on >2 machines

I have 3 Mysql servers that I would like to replicate: two (including the main server) are local and one is remote. Let's call my main server A, the secondary server B, and a remote, development ...
3
votes
1answer
160 views

Constrains relationship

I have the following design. Each user has it's own contacts, it's own hosts and assign those to a domain which belongs only to him. I want to insure that the host you assign to the domain belongs ...
3
votes
1answer
2k views

query cache hit value is not changing in my database

The query cache hit value is not changing in my database only for some queries.If I write select * from drugs_info limit 1000; the query cache hit has changed, but if I execute the following ...
2
votes
1answer
579 views

row locking within ACID transaction innodb

I have a financial transaction that looks something like this (pseudo): begin select record for update update record(same record as selected) insert another record into another table ...
2
votes
2answers
1k views

Which first: upgrade mysql version or convert storage engine?

I inherited a production mysql server at 5.0. It uses MyISAM exclusively. It is not a high volume database but it does have some large datasets. I am planning on: upgrading to 5.5 converting ...
2
votes
1answer
182 views

Combining columns in index

With reference to RolandoMySQLDBA's answer on MySQL: Index when joining to tables not being used (Performance optimizing question) He mentioned Make sure you build an index that involves the ...
2
votes
1answer
2k views

Create a custom log table in MySQL

Is it possible to create a custom log table. For example I have 10 schema and I would like to log if somebody is using the "areva" schema. I want to know the last executed command time and the user. ...
224
votes
15answers
96k views

Can MySQL reasonably perform queries on billions of rows?

I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies ...
61
votes
5answers
7k views

How can a group track database schema changes?

What version control methodologies help teams of people track database schema changes?
10
votes
2answers
20k views

What is the Best Way to create MySQL Master-Slave Replication Setup and Troubleshoot it?

I am very new to Database Administration. I face a lot of problems while setting up mysql master-slave replication. I also face regular mysql replication troubleshooting issues. Can anybody helps ...
17
votes
5answers
50k views

How to properly kill MySQL?

I have CentOS 64bit with CPanel installed and I use service mysql stop However, it keeps doing ..... for minutes and it never stops. It used to be instant. Any idea why it does that and how to fix? ...
25
votes
8answers
17k views

Tool to generate large datasets of test data [closed]

Many times when trying to come up with an efficient database design the best course of action is to build two sample databases, fill them with data, and run some queries against them to see which one ...
11
votes
3answers
19k views

Why is 'LOAD DATA INFILE' faster than normal INSERT statements?

I've read an article that mentioned we can achieve 60,000 inserts per second by LOAD DATA IN FILE statement that read from csv files and insert it into database. Why should it differ from normal ...
12
votes
5answers
27k views

Cannot open table mysql/innodb_index_stats [duplicate]

After a fresh install of XAMPP and import from my linux live db that is working to the windows Dev-stage, I started encountering problems with INSERT. Everything else seems to work well. The errors I ...
11
votes
6answers
28k views

Fastest way to check if InnoDB table has changed

My application is very database intensive. Currently, I'm running MySQL 5.5.19 and using MyISAM, but I'm in the process of migrating to InnoDB. The only problem left is checksum performance. My ...
14
votes
1answer
14k views

Dump only the Stored Procedures in MySQL

I need to dump only the stored procedures : no data, no table creation. How can I do this using mysqldump?
7
votes
3answers
10k views

InnoDB table SELECT returns ERROR 2006 (HY000): MySQL server has gone away (after power outage)

This server is a virtual machine running CentOS 6.0, MySQL 5.5.21 There is a database named devSystem. There are InnoDB tables within. Running the following commands causes error ERROR 2006 (HY000):...