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

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What can cause TRUNCATE TABLE to take a really long time?

I'm running MySQL5.5 with Master/Slave replication (1 master, 2 slaves). I have a process that runs once a week and truncate a specific table. The table is not large and only has a few thousands ...
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1answer
8k views

increasing mysql table open cache?

I often read that it is best to increase this variable slowly. Can someone explain why? My status indicates that I should increase it... What is best practice / "slowly"? Thanks!
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Is my.cnf for mysql 5.5 is suitable and well tuned for below hardware spec?

My Hardware Spec Technology: Ivy Bridge CPU: Intel Xeon E3 1245v2 Intel Smart Cache: 8MB Cores / Threads: 4 / 8 Frequency: 3.4GHz+ / 3.8GHz Turbo Boost RAM: 32 GB DDR3 Hard disk: 2x 2TB SATA3 Raid 1 ...
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Why max_allowed_packet is larger in mysqldump than mysqld in my.cnf?

If you look at the sample config such as /usr/share/mysql/my-large.cnf, you will find.. [mysqld] max_allowed_packet = 1M [mysqldump] max_allowed_packet = 16M What is the point? Because when you ...
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1answer
2k views

Unknown option '--no-beep'

I installed a new version of MySQL server (previously 5.0, now 5.5) and I copied the data folder in to the new one. Now I should perform mysql_upgrade. I opened the command prompt (server is located ...
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2answers
5k views

Cannot configure nor start MySQL

On a brand new Kubuntu 14.04 install, I ran sudo aptitude install mysql-server-core-5.6. The install could not complete due to dependencies of some KDE packages on mysql-server-core-5.5, which would ...
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2answers
100 views

Query only for the first n results of like

What I'm trying to accomplish is a huge speedup (read: incremental results) when searching a database with a like operator which is kind of a last resort, if everything else already failed, to come up ...
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2answers
1k views

Replication error

We have a slave server that has stopped replication due to the following error: Slave SQL: Query caused different errors on master and slave. What could be the cause of this error? And what would ...
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1answer
1k views

Query not using index when it should

I have this query (below) which keeps hitting the table when it should be using the created index. Is there something simple I'm missing here? How can I get it to use the index instead of the table? ...
4
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1answer
466 views

How to Update same table on deletion in MYSQL?

In my Database I have a table: Employee with recursive association, an employee can be boss of other employee. Following is query I used to create table: CREATE TABLE IF NOT EXISTS `Employee` ...
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1answer
3k views

Can I safely kill OPTIMIZE TABLE on an InnoDB table?

MySQL's documentation for kill warns: Warning Killing a REPAIR TABLE or OPTIMIZE TABLE operation on a MyISAM table results in a table that is corrupted and unusable. Any reads or writes to ...
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3k views

Setting up MySQL Cluster on Two Systems

I am attempting to setup a MySQL Cluster. I have the folllowing setup one management node two data nodes another machine on which two more nodes reside Below is the config.ini file: [ndbd ...
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3answers
290 views

Why set up static data in views vs. using tables in mysql?

I get an LDAP feed nightly. I get it as a text file and dump/create my LDAPALL table. There are roughly 75K employees times about 50 fields. I have the following too: LDAPIMPORTANT - view that ...
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2answers
5k views

What to use, CASCADE DELETE rule or ON DELETE trigger for one to many constraint?

I would like to ask about how to handle this relationship. For better view I've tried to simplify and convert my situation into how I think StackOverflow question voting has (sorry if not :-) I ...
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2answers
4k views

MySQL equivalent of WITH in oracle

I need the mysql equivalent of the WITH clause in Oracle. Please help. Thank You
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1answer
333 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 ...
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2answers
810 views

How to split a string to and get info from another table in mysql

I have a system to assign score for each sentence stored in a column: TABLE 1: word_scores word score this 3 is 4 a 5 test 1 another 0 sentence 8 TABLE 2: ...
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4answers
9k views

How to Add Federated engine after installing Mysql

I have Mysql 5.5.18 and upon show engines: show engines; +--------------------+---------+------------------------------------------------------------+--------------+------+------------+ | Engine ...
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2answers
99 views

Why wouldnt Mysql use index on the Primary query in a nested query

I have two tables: search_criteria and pricing. There is an index on search_id column in search_criteria table and on pricing_id column in pricing table. But running this nested query does not use ...
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2answers
4k views

MySQL 5.5 High CPU Usage

I have been working with a client with high traffic website(500k visitors and 600-800 active users at any given time). This uses wordpress and the DB is using MyISAM engine. The problem we had was ...
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3answers
3k views

InnoDB insertion faster

I'm a graduate school student researching OLAP with Mondrian OLAP. So I want to insert data into InnoDB (MySQL 5.5) faster at the initial loading. In this environment, the only user is me, so I think ...
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3answers
2k views

MySQL optimization - year column grouping - using temporary table, filesort

I have a transactions table which is having 600,000 records, I need to list the count for the dashboard on financial year basis. The table used is MyISAM. I tried adding index for the transaction date ...
3
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1answer
58 views

where varcharcol = 0 returns all rows

Suppose I have a table like this: create table mytable(cola int primary key, colb varchar(10)); Let's put some data in it: insert into mytable values(1, 'abc'); insert into mytable values(2, ...
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2answers
2k views

MySQL replication to slave having VPN connection to Master

I am setting up an environment in which the Master and Slave are on different networks at different physical locations (both run on MySQL 5.5.20). I have set up a VPN connection from slave's network ...
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2answers
8k views

ALTER TABLE - Rename a column

This got me nuts! I want to rename a column from read-more to read_more in blog table Tried all this: ALTER TABLE blog RENAME COLUMN read-more to read_more; ALTER TABLE blog CHANGE COLUMN ...
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1answer
647 views

Which is more efficient, trigger or PHP code?

My requirement is to move EMR data for a patient to a set of history tables when the patient has been discharged. I proposed to use an after trigger on the table housing the discharge flag, checking ...
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1answer
1k views

MySQL 5.5 InnoDB = OFF?

We run a server with MySQL 5.5. 95% of the tables are set to the InnoDB engine. However whenever I look at the my.ini file (using the MySQL Workbench) under mysqld section innodb is unchecked and OFF ...
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2answers
56 views

Fetch all words from column with like

I have a column with description and inside it can contain # value . what I want is all the words searched from that column with #tag This is my query SELECT description FROM photo where ...
3
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1answer
308 views

How to store static list of hashes in MySQL effectively?

Problem: I have a list of pairs (md5_hash, id). I want to store the data in MySQL and I want to make queries like this SELECT id FROM table WHERE md5_hash = <some_hash> The number of pairs ...
3
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1answer
3k views

Recover the disk space after deleting rows from table

I deleted millions of rows from one of the table with innodb engine. I know that I need to run optimize table to recover the space. But running that will cause lock on the table, which will affect the ...
3
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4answers
929 views

Stress Test to Saturate Memory for MySQL InnoDB

I'm investigating windows 32bit memory problems (the 2G limit) and am after a test which will max out MySQL's memory including InnoDB Buffer Pool, per connection memory and/or any other uses of ...
3
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1answer
155 views

Backup and off-site restore setup

I've been reading a lot of threads about different backup options for MySQL and was hoping for some more insight so I can settle on one. Our current situation is ~100 GB of InnoDB and MySAM data in ...
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1answer
225 views

Get profiles values where message.sender_user_id = profile.user_id

I have this tables: default_messages CREATE TABLE IF NOT EXISTS `default_messages` ( `id` int(11) NOT NULL AUTO_INCREMENT, `subject` varchar(150) COLLATE utf8_unicode_ci NOT NULL, `message` text ...
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2answers
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Can we assign mysql Key_buffer_size value for particular table?

In some documents I found that we can assign key_buffer_size to myisam table. This also includes the following steps: SET GLOBAL myisam_table.key_buffer_size = 4194304; CACHE INDEX test.myisam_table ...
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2answers
72 views

Is this substring_index behaviour documented or a bug?

mysql> show variables like 'version'; +---------------+-------------------------+ | Variable_name | Value | +---------------+-------------------------+ | version | ...
3
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1answer
339 views

Online Schema migration in MySQL : When to start?

I'm the tech lead of a Social Media SAAS, where we're currently experiencing a big increase in data amount we're storing in our mySQL-database. We're having a single MySQL db, and besides many ...
3
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1answer
2k views

MySQL: Alter Table on very active table gives “Waiting for table metadata lock”

At my work, we've recently upgraded to MySQL 5.5 and since then, have been bitten a few times by the new (and intended) behavior of metadata locking. Basically, whenever we run an ALTER TABLE ...
3
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1answer
337 views

MySQL / Fusion IO Configuration Question

I need a little configuration optimization. I think what I have is pretty good but feel like there's still room for improvement. Current Config [mysqld] user=mysql datadir=/var/lib/mysql ...
3
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1answer
124 views

MySQL Replication not proceeding

I have a weird replication problem I have not seen before. It's basic mysql replication with single master and two slaves. One of the slaves is not executing replication events and seems just stuck ...
3
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1answer
558 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 ...
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2answers
8k 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 ...
3
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1answer
2k views

MySQL Slave Relay Logging but not logging Binary Log

I have a master slave setup both mysql 5.5, the setup is fine except that the slave won't Binary log to the standard mysql-binlog only to the relay logs. I fear this may be due to my lack of ...
3
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2answers
642 views

How to concatenate a column after x rows?

I have a table with columns object varchar(255), frequency tinyint(3) unsigned, I want to concatenate the objects if the sum of frequencies reach a value. Currently I am doing this in PHP as .. ...
3
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1answer
278 views

how to add removed partition?

This is the structure of my table: -- Table: t_keyword_conversion_ga -- Create Table: CREATE TABLE `t_keyword_conversion_ga` ( `id` int(11) NOT NULL AUTO_INCREMENT, `own_domain_id` int(11) DEFAULT ...
3
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1answer
2k views

Slow insert performance in mysql innodb table for solr indexing

I have a Slave server (MySQL 5.5) having innodb tables. This server is being used for SOLR indexing. Few procedures used to fill 12 million data into 9 tables. The insertion speed is too slow. ...
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1answer
5k views

How to grant access for multiple tables to a user in MySQL DB?

I have mysql db named "greats" with four tables as below +---------------------+ | Tables_in_greatstat | +---------------------+ | log | | sitedet1 | | siteindex ...
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1answer
876 views

Keeping MySQL staging database on same server updated from production

I just migrated my MySQL 5.5.20 to Amazon RDS from MySQL on EC2. The one thing I'm having difficulty with is how to keep my staging database updated from production. Before, I just ran a nightly ...
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1answer
2k views

What does the base64 BINLOG statements in mysqlbinlog output mean?

I have looked over the mysqlbinlog command as a candidate for rollback method from MySQL 5.5 to MySQL 5.0. When I ran the command on one of the bin-log files in the MySQL 5.5 server, I've noticed ...
3
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1answer
312 views

MySQL RDS Instance eating up memory and swapping

I have an issue with memory on a RDS instance which is of db.m2.4xlarge class. Below are the specifications of the RDS instance Instance Class: db.m2.4xlarge ( 68.4 GB of RAM ) Engine: ...
3
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1answer
224 views

mysqladmin - u root -p ping is not executing

I am getting the below error in mysql while trying to ping. i am using mysql version 5.5.37-0ubuntu0.12.04.1. when ever i use mysqladmin i am getting the below error. Please suggest how to clear this ...