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

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4answers
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How to Add Federated engine after installing Mysql

I have Mysql 5.5.18 and upon show engines: show engines; +--------------------+---------+------------------------------------------------------------+--------------+------+------------+ | Engine ...
3
votes
1answer
3k views

InnoDB: Error: Table “mysql”.“innodb_table_stats” not found after upgrade to mysql 5.6

I upgraded to mysql 5.6 from 5.5, and now my logs are littered with such messages on startup I found a possible solution here, but it does not seem official. ...
3
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2answers
537 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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3answers
2k 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 ...
3
votes
3answers
1k 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
votes
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, ...
3
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2answers
1k 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 ...
3
votes
1answer
425 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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3answers
1k views

What are the limits on the amount of slaves per master?

I currently have a Master with 2 slaves, all running MySql 5.5. What are the limitations on the amount of slaves I can connect to a single master? what parameters should be taken into affect?
3
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1answer
932 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 ...
3
votes
1answer
178 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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4answers
704 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
5k views

SUPER privilege not defined for master user in Amazon MySQL RDS

I have created one medium instance on amazon rds in asia pecific (singapore) region. i have created my master user with master password. and it is working/connecting fine with workbench installed on ...
3
votes
1answer
129 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 ...
3
votes
1answer
210 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 ...
3
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2answers
1k views

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 ...
3
votes
1answer
117 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
votes
2answers
913 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 ...
3
votes
1answer
91 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
votes
1answer
385 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 ...
3
votes
1answer
669 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? ...
3
votes
1answer
1k 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 ...
3
votes
2answers
535 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
votes
1answer
134 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
votes
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. ...
3
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1answer
737 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 ...
3
votes
1answer
1k 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
votes
1answer
82 views

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
votes
1answer
363 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
votes
1answer
190 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 ...
3
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2answers
5k 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
votes
1answer
211 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. ...
3
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1answer
333 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` ...
3
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1answer
752 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
votes
1answer
157 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 ...
3
votes
2answers
177 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 ...
3
votes
2answers
76 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 ...
3
votes
2answers
140 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 ...
3
votes
2answers
1k 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
votes
2answers
9k views

innodb_flush_method=O_DIRECT vs O_DSYNC performance impact on ext3 with LVM disk partition

In one of my production environment, we have two instances running on a RedHat cluster, with one production instance associated with the cluster. We have 125G main memory with 24G InnoDB buffer pool ...
3
votes
3answers
303 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
votes
1answer
467 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) ...
2
votes
4answers
2k 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 ...
2
votes
2answers
430 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> ...
2
votes
2answers
5k 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 ...
2
votes
2answers
87 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 ...
2
votes
2answers
175 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?
2
votes
2answers
719 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 ...
2
votes
4answers
285 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`; ...
2
votes
3answers
3k 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 ...