MySQL 5.5 brought many performance enhancements and expanded the feature set of the popular open-source RDBMS.

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How to upgrade MySQL (5.5) production DB to 5.6 with minimal downtime

Our existing Database size around 200GB. We want to use consistent, parallel backups methods. For testing, I migrated my Development DB from 5.5 to 5.6 by running mysqldump with option ...
3
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1answer
608 views

Getting Random Sample from large database MYSQL (No Auto Inc Field)

You were so helpful with my last question, I thought id throw another one at you thats stumping me. Basically I got a table, requirements from company was it was all supposed to be 1 table so I got ...
3
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1answer
230 views

MySQL Stress testing issues?

I had gone through MySQL High Performance book Chapter 2 for MySQL Bench marking and Profiling,I have some questions about benchmarking How can we test an existing database and queries against it ...
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3answers
2k views

MySQL information_schema doesn't update

I have a database, say abc, in mysql server. It has only one table named test. test uses innodb engine and I've set innodb_file_per_table to true. After I run the query delete from abc.test, I want ...
3
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1answer
249 views

What's the most unsafe MySQL configuration?

I have MySQL 5.5.27-29.0-log instance running specifically for Jenkins. Since tests data is always recreated during setup, ACID is unnecessary and I'm hoping to sacrifice it to gain more performance. ...
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1answer
491 views

Do I need to index a key that I partition by?

I have an InnoDB table of customers, partitioned by KEY, with each partition being one US state. I have an index on phone number, and the performance is great. We also need to SELECT by last name in ...
3
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1answer
1k views

Configured MySQL replication but its not working

I have configured MySQL master and slave replication setup on 5.5.x. But for some reason data is not getting replicated properly. What might be the reason? At Master: /etc/my.cnf [mysqld] ...
3
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1answer
211 views

mysqld-multi with first DB as Slave and second DB as Master

Yesterday, I setup mysqld-multi in my.cnf. It works fantastic, but there is still a further Problem. The first DB on socket 1 running as Slave from a other server. The second one from socket 2 ...
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0answers
46 views

Is it a waste to set innodb_buffer_pool_instances greater than the # of CPUs?

I set the innodb_buffer_pool_size to 20GB on a server with 12 CPU cores. My full database is 11gb, however most of it is archived tables that are almost never used. The total queried data is around 3 ...
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4answers
639 views

MySQL runs out of memory when importing innodb database

I have a small VPS with 512MB RAM and no swap (can't have any). I am importing a 1.5GB innodb database with mysql -u -p < database.sql Before the operation can finish it says : Lost connection ...
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2answers
184 views

Problem in Fetching Result set in Desired Format

I have 2 tables having the following columns Person ------ person_id, first_name, middle_name, last_name Items ----- person_item_id, person_id, item_type, status, ordered_date The query is ...
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427 views

Finding differences between a master and slave when pt-table-sync fails

I have a table that's showing some differences on a master and slave according to pt-table-checksum (PTC). I've found some verifying differences beyond that. Certain tables in the mix have composite ...
3
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1answer
709 views

Convert Oracle Query for Date to Mysql queries

Need to convert the following oracle queries to MYSQL queries. 1) select to_char(to_date(?,'DD-MM-YY')) from dual; 2) select to_char(next_day(to_date(?,'DD-MM-YY'),'FRIDAY')) from dual; 3) ...
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4answers
3k views

Creating Archiving database for old data in MySQL

I Have a Master and Various Slave Servers. There is a huge amount of the data on all the servers and I wish to create an Archiving system for our Data. Scenario is : I want that only Last one year ...
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2answers
8k views

MySQL Error Reading Communication Packets

In MySQL error logs, I see these quite few a warnings like these: 120611 16:12:30 [Warning] Aborted connection 2619503 to db: 'db_name' user: 'user_name' host: 'webapp_hostname' (Got an error reading ...
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2answers
561 views

Tool to match mysql password encryption

I've created a user ... but forgotten the password mysql> create user 'blayo'@'%' identified by 'right'; Which Linux command line tool can encrypt the password the same way mysql does ? mysql> ...
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2answers
143 views

How to store logs correctly?

(This is somewhat a follow up on my last question) I am using MySQL 5.5 with innodb. My Log table consists of two columns. One for user number, and the other for a string consisting of IP, request ...
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2answers
233 views

Tinyint structure is confusing

I am confused to see this tinyint(3) structure. If tinyint can store only 1 byte then what is the purpose of giving the size in brackets? Is there something special with this parameter in MySQL?
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2answers
854 views

How to GROUP_CONCAT between given rows?

I have a table as id diary 1 breakfast 2 walk 3 start 4 office works 5 office projects 6 end 7 taxi 8 start 9 preparing for meeting 10 doing the meeting 11 end 12 night I want ...
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4answers
329 views

Does my table violate normalization rules?

I am developing an emulator for a game. My item table looks like this: -- ---------------------------- -- Table structure for `items` -- ---------------------------- DROP TABLE IF EXISTS `items`; ...
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3answers
5k views

innodb_buffer_pool_size not changed

I use MySQL 5.5.23-1~dotdeb.0 (Debian) and here is the relevant part of my.cnf default-storage-engine = innodb innodb_buffer_pool_size = 3G innodb_log_file_size = 256M innodb_thread_concurrency = 8 ...
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2answers
5k views

“Could NOT find Curses” error when installing MySQL from source

I am installing MySQL Server from the source distribution which I downloaded from: http://dev.mysql.com/downloads/mysql/#downloads. I have downloaded the file (mysql-5.5.19.tar.gz). I am using ...
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2answers
273 views

Are there benefits to using more than 4 CPUs for MySQL?

We are running MySQL 5.5 on linux under VMWare, running on 2 CPUs. We are planning on increasing this to 4, but we have un-used CPUs available, and I'm wondering if there is any benefit to increasing ...
2
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1answer
184 views

Is there a way to achieve Workload Management in MySQL?

Is there a way to set up Workload Management in MySQL (in particular v5.5 on AWS RDS)? By Workload Management I mean the functionality implemented in e.g. Teradata, RedShift that allows ...
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2answers
1k views

Changing the mysql.proc table directly after upgrade

Our host upgraded our mysql install without us knowing from roughly 5.1 to 5.5. This caused a problem because the table definition of mysql.proc is different as discussed here: ...
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2answers
838 views

Does MySQL 5.5 support shared database with separate schema?

I am developing a SaaS based product using MySQL 5.5 as the backend database. I want to keep shared database for all the tenants, but separate a database schema of each tenant. There would be a single ...
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2answers
559 views

MySQL - How much physical space will be reduced by changing the column type?

Lets say I have the following table: CREATE TABLE `my_table` ( `id` int(11) NOT NULL AUTO_INCREMENT, `user_id` int(11) NOT NULL, `relationship_status` varchar(48) CHARACTER SET utf8 COLLATE ...
2
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1answer
160 views

Need some help with this query get all status and their associated comments of me and all my friends

I've several days dealing with this query but can't get it to works as I want. This post is related to this one Several values from different tables in which I tough found the solution but I was ...
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3answers
1k views

MySQL backup with no downtime [closed]

I'm running a M/S replication of MySQL 5.5 / innoDB (over ubuntu). My DB is pretty large: ~250GB. I'm looking for a backup tool/service that will do the following: full backup no downtime / locks ...
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2answers
3k views

How to improve MySQL Server Performance..??

As a MySQL DBA most of the times we are supposed to optimize a poorly performing MySQL Servers. Now my question is where to start from like we will need to find out many things as 1.Find the ...
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2answers
4k views

MySQL Table level Replication

I have 3 servers, say A,B &C. All have the equivalent data(same data). Now what I want is to make A as the master and B,C the slaves. But the scenario is that I only want to replicate some of the ...
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1answer
2k views

Mysql INSERT INTO .. ON DUPLICATE KEY UPDATE

I'm trying to do the following query in mysql 5.5 INSERT INTO countingTable( image_count, article_id ) SELECT COUNT( article_id ) AS sum, article_id FROM imageTable ON DUPLICATE KEY UPDATE ...
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4answers
256 views

Aggregate query optimization

Could you please help me to optimize this query - currently it takes ~4 minutes to run this query. It looks like keys: ip and timestamp are non-unique so shall I add some indexes? mysql> EXPLAIN ...
2
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1answer
622 views

Mysql 5.5 InnoDB growing CPU - Going crazy

Good morning, I'm currently facing a problem where CPU usage keeps going up until the server crash. I've tried multiple best practices proposed in this forum and on Percona, reinstalled the server ...
2
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1answer
383 views

MySQL with high CPU and memory usage

here we have a VPS with 3.2GHz quadcore processor with 2GB of RAM and 4GB of SWAP which need to work with a high intensive legacy system (read: bad coded). The main problem is that the CPU (~80 - ...
2
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1answer
1k views

Is it possible to force drop of mysql tables with FK?

For dropping a table in which a Foreign Key is used in other tables, it is necessary to drop all other tables having FK connection with the corresponding table. Is there a short way to drop a table, ...
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3answers
1k views

how to install mysql on mac?

My Mac runs Mac OS X, version 10.7.5., so it's a 64 bit system. First, I downloaded mysql-5.5.28-osx10.6-x86_64.dmg. Then I double clicked mysql-5.5.28-osx10.6-x86_64.dmg, it's mounted, and shows ...
2
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1answer
94 views

Why does MySQL increment the auto_increment value when there's a constraint violation?

I have a table in a MySQL database with one column id, which has auto_increment and the Primary Key. There's also a Unique constraint in this table, on different columns. I noticed that when I try to ...
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2answers
2k views

High MySQL “InnoDB Writes Per Second” - Can't see the queries?

On our live MySQL 5.5 database server, we use MySQL Workbench for running manual queries, checking running queries to see what's going on, etc. I noticed today that on the "Server Status" tab there's ...
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3answers
222 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
826 views

Fastest way to create local copy of live InnoDB MySQL database?

We have a MySQL database (InnoDB) on our live Ubuntu 12.04 server which has grown quite large (25gb+). Every month or so we need to copy this database to our development machines to work on locally. ...
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2answers
731 views

How to SELECT rows with time duration stored in varchar column?

There is a column in table defined like this : duration varchar(10) It has value for duration of a MP3 file stored in it like : 52:19 (Minutes : Seconds) How can I create a SQL query, for ...
2
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1answer
3k views

Upgrading MySQL 5.1 to 5.5 on Centos 6 without removing dependencies

I'm trying to upgrade MySQL 5.1 to 5.5 using yum/rpm combo (yum to remove MySQL 5.1 and rpm to install MySQL 5.5). Most instructions I've found suggest to do first: yum remove mysql mysql-server ...
2
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1answer
105 views

Need to Rewrite/optimize Slow Query

I have a query with following explain plan EXPLAIN SELECT COUNT(applicant.id) as applicantCount, application.name,applicant.application_id,application.id FROM applicant LEFT JOIN application ...
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2answers
9k views

MySQL using too much CPU

I'm studying to be a DBA right now because I have a massive live database that is very sensitive that I manage. Here's the current system stats of my dedicated database server: CentOS 5.9 24gb Ram 8 ...
2
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1answer
1k 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 ...
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2answers
2k views

mysql 5.5 corrupt - missing temporary table

One of our mysql instances crashed and failed to start: 120422 10:04:13 InnoDB: Error: trying to open a table, but could not InnoDB: open the tablespace file './databasename/#sql-29f6_45.ibd'! ...
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2answers
534 views

Any problem will all InnoDB and one MyISAM table?

I have a MySQL 5.5 DB with all InnoDB tables. For some reason, one of the developers decided to create a MyISAM table. It is a log table for user sessions. I don't see why we should mix in a MyISAM ...
2
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1answer
63 views

How can I determine which Innodb table is being written?

I am running Mysql 5.5. I have about 100 Innodb tables spread over 10 DB's (mostly wordpress sites) and I am recently seeing a lot more disk IO than I have been, without any increase in traffic. The ...
2
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1answer
71 views

MySQL - Get Minimum Value, Data From Multiple Tables

Good evening all, first post on the DBA forums. I am having real issues working out how to accomplish a seemingly simple task within MySQL as a model for PHP code later on. I am not exactly a MySQL ...