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

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1answer
42 views

How to decipher the transaction message in innodb status log.

I have several transactions that seem have stalled. Looking at the innodb status log, I found several messages similar to the following: ---TRANSACTION 69DBBB, ACTIVE 947 sec starting index read, ...
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3answers
230 views

How to update cust_id from Customer table to order table Cust_id field while inserting customer name using trigger

I have two tables 1. Customer_details and 2. Order_details. 1.Customer_details table -->fields--> Cust_Id(Primary Key) and Customer_Name, 2.Order_details table --> fields-- Ord_Id(Primary ...
2
votes
2answers
1k views

changing TEMPORARY TABLE default collation

when I use CREATE TEMPORARY TABLE to create a temporary table, the collation of this table is utf8_unicode_ci by default. why by default it is utf8_unicode_ci? How can I change the default?
2
votes
1answer
76 views

Make sure slave has finished reading from master

I am planning to have a master-slave system in which occasionally the master and slave will reverse roles. To do this, I will stop further updates to master, and redirect traffic to the slave. But, ...
2
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1answer
196 views

MySQL Subquery hangs / terrible perfomance

I am using MySQL 5.5.16 @ CentOS. Please have a look at this query: SELECT inventory_ID, ( SELECT price_brutto FROM _inventory_prices ...
2
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1answer
924 views

Table corruption: How to perform Innodb Checksum checks in MySQL 5.5 for Windows?

Having a corrupted Mysql 5.5.31 (Windows) database, my question relates to the the top solution provided in How do you identify InnoDB table corruption? , more precisely to the following script that ...
2
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3answers
4k views

How to import table's data in MySql from Sql Server?

I am trying to export table from SQL Server 2008 R2 TO MySql 5.5. For this I am using SQL Server Import and Export Wizard of Sql Server 2008, but it is giving this error. Here this error may be ...
2
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1answer
78 views

System to track what Zip Codes my vendors service

I am designing a table configuration that will contain all of the zip codes in the United States. I have a .csv file of all the zip codes in the U.S., so thats at least a start. This will end up as a ...
2
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1answer
3k views

MySQL 5.5 - determining correct write[read]_io_threads on high-end system?

Specifically dual-CPU 32 core - 128RAM - RAID 10 SSD . Ubuntu 64 server. Heavy Innodb load at times - ~ 2000+ queries per sec. Heavy read and write. Currently we are running on the default ...
2
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1answer
351 views

Null Values and Performance

I always try to build the database avoiding any NULL values in my tables, and I have successfully had done this so far. (Hey, I am very new to database design.) But still there are times when saving ...
2
votes
1answer
92 views

Count total where owner_user_id = some_value and deleted_by_owner = 0 or to_user_id = some_value and deleted_by_to = 0

I didn't know if this is possible using just a query or if I need some procedural logic on this one. I have this table: CREATE TABLE `default_messages_users` ( `id` int(11) NOT NULL ...
2
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2answers
128 views

How to see what was executed in the database via binlogs for specific date?

I am trying figure out how to "query" binlogs to see what was exectued in the database for a specific date. For example, if I execute mysqlbinlog binlog then the thing just runs forever and it is had ...
2
votes
1answer
391 views

Assertion failure from InnoDB while restoring using Innobackupex

I thought I would give back to all those people who help me when I have a problem. This might be something old, but I did not find it anywhere so here goes: We recently upgraded our production DBs ...
2
votes
1answer
660 views

Database Design - Creating Multiple databases to avoid the headache of limit on table size

I need to design database to store information contained in millions of log files generated by devices on trial on network. My first approach was storing all the information in tables contained in a ...
2
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3answers
1k views

InnoDB UPDATE slow need a better option

I'm using MySQL 5.5 with a table in InnoDB running: deleteme tinyint NOT NULL DEFAULT 0;` UPDATE `import` SET `deleteme` = 1; -- Set the delete field LOAD DATA LOW_PRIORITY LOCAL INFILE ...
2
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1answer
3k views

What is the optimal way to select the parent and child rows on a table with a self-relationship?

Sample data from the genres table: id | genre_name | genre | parent_id --------------------------------------------- 2 | Blues | MAIN | NULL 6 | Folk | MAIN ...
2
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1answer
2k views

Ubuntu Multiple MySQL instances and Apparmor

I am trying to set up multiple instances of MySQL on an Ubuntu dev machine and running into AppArmor problems. I get this error in the syslogs: kernel: [227631.776360] type=1400 ...
2
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1answer
230 views

Innodb mutex locking ?!? Inserts start stacking after 18-24hours, restart required

We have a fairly high end box running mysqld 5.5.20. The cpu configuration is dual quad core xeons. It has 32 gb ram. It has a quad intel ssd configuration running raid 0+1. On a fairly busy ...
2
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1answer
146 views

View last several innodb deadlocks

I see that I can view the latest deadlock in mysql/innodb, but is there a way to view past deadlocks? We have two deadlock issues, one being important and the other not. The less important deadlock ...
2
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0answers
51 views

Emulating WITH clause in MySQL/query perfomance review

I have never really worked with MySQL queries till this last week. I was tasked with making a simple tool for my department that tracks contacts. Here are the 2 tables and the type of data they ...
2
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0answers
21 views

MySQL slow query log not logging all slow queries [duplicate]

I am trying to analyze the hibernate query performance in our application. I tried logging all hibernate queries which take more than 100ms execution time from application side as well as using mysql ...
2
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2answers
205 views

Is there a rule of thumb regarding the size and number of a buffer pool instances?

I know the consensus seems to be approximately 75% of ram should be dedicated to the buffer pool. But, I'm more interested in the optimal number of buffer pool instances. What are some things to ...
2
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0answers
101 views

Understanding Indexes and using them better

I've been spending some time trying to optimise our MySQL queries that we use which essentially joins one table with 2 million rows onto another which has 1-2 million. I know MySQL is able to easily ...
2
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2answers
194 views

Repeated values in group_concat

I have two tables, first the table food and Second is Activity: INSERT INTO food (`id`, `foodName`) VALUES (1, 'food1'), (2, 'food2'), (3, 'food3'), (4, 'food4'), (5, ...
2
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1answer
219 views

In MySQL, does the order of the columns in a WHERE clause affect query performance,why? [closed]

I have a query that doesn't use any indexes: SELECT 32, guid, 1, 1, 1, 0, 5 FROM test WHERE level >= 20 AND ( ( fun_GetIndexValue(data, 354) ...
2
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1answer
221 views

innobackupex is failing while exporting backup

I am using perl script which is working fine in one of my other box which used to take individual schema backups & finally take all schema together using percona innobackupex. I have following ...
2
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4answers
976 views

Getting 0KB of size file while backup mysql database using mysql dump [closed]

I am using below code to backup my database using php script but I am getting 0KB size file. How can I backup my full database with all routines and functions? $dbhost = 'localhost'; $dbuser = ...
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3answers
6k views

Difference between On Delete Cascade & On Update Cascade in mysql

I have two tables in MySQL database- parent, child. I'm trying to add foreign key references to my child table based on the parent table. Is there any significant difference between ON UPDATE CASCADE ...
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2answers
1k views

Warnings: Why are statements with limit clause unsafe even if there isn't a limit?

I'm a bit irritated because of some warnings in mysql errorlog. Example 1: [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. The statement ...
1
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2answers
124 views

Is column order reliable in UPDATE?

Can we reply on the order of columns in an UPDATE? SET @x = 0 UPDATE table1 SET col1=IF(col1 IS NULL, NULL, @x:=@x+col1), col2=IF(col2 IS NULL, NULL, @x:=@x+col2), col3=IF(col3 IS NULL, NULL, @x:=0) ...
1
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3answers
963 views

Please review the My.INI settings of my PC. File Attached

Below is the my.ini file of one of my PC running MySQL 5.5 with 1 GB RAM. It is not using concurrent connections and we are using a stand-alone PC for a single application and single user. # MySQL ...
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3answers
72 views

Mysql Master Offline

In a unidirectional Master-Slave setup, should the slave be manually stopped in cases where the Master is offline due to Maintenance, Crash etc. ? Or should one just leave it so that it keeps trying ...
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3answers
72 views

MySQL backup breakes a table every time

I've a MySQL Server 5.1.58-1ubuntu1 installed on an Ubuntu 12.04 LTS. Every night we do a backup of all the databases with this script: rm -rf /var/backup/mysql/ * for i in $(echo 'SHOW DATABASES;' ...
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1answer
10k views

Enabling LOAD DATA LOCAL INFILE in mysql

LOAD DATA LOCAL INFILE is not enabled by default. Normally, it should be enabled by placing local-infile=1 in my.cnf. But it does not work for all installations. In my experience, it worked for Debian ...
1
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1answer
245 views

INSTALL PLUGIN 'rpl_semi_sync_master' SONAME 'semisync_master.so' not working

I'm trying to install semi synchronous replication in my mysql 5.5 and trying to execute the below command: INSTALL PLUGIN 'rpl_semi_sync_master' SONAME 'semisync_master.so' but this command is ...
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3answers
2k views

MySQL: Trying to update to 5.5

I've followed this instructions, but after mysqld --skip-grant-tables --user=mysql, I'm getting this: 110913 20:29:18 [Warning] Can't create test file /var/lib/mysql/my-laptop.lower-test 110913 ...
1
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3answers
92 views

Index optimization and cardinality

I'm by no means a DBA expert. Rather, a Magento developer having to troubleshoot some slow queries. I'll jump right in -- here's my attempt to EXPLAIN the troublesome query: EXPLAIN SELECT ...
1
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2answers
245 views

grant select on all databases except one mysql

I have user called test_user created under MySQL 5.5.17 under MS Windows 2008R2, I want to grant this user select privileges on all databases except MySQL database, note I have around 200 database ...
1
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4answers
133 views

How to backup live mysql database?

I have 12 GB MySQL InnoDB Database with around 800 queries per second. No sooner I start 'mysqldump' over it to make backup I start getting '503' on my website. How do I make backup of my live ...
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1answer
161 views

MySql - unique key not working

I have the following table: CREATE TABLE `timeline_lists` ( `id` int(11) NOT NULL AUTO_INCREMENT, `user_id` int(11) NOT NULL, `list_type` int(11) NOT NULL, `s_object_id` int(11) NOT NULL ...
1
vote
1answer
3k views

Add database to existing replication which uses binlog_do_db?

We have two MySQL 5.5 servers running on Ubuntu 12.04. We are successfully replicating 3 databases from server01 to server02, but need to add a 4th (new) database. Our my.cnf on the master has: ...
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1answer
29 views

Is it possible to find the user whose aggregated score reaches X value first?

Given this sample fiddle containing sales value and date for two users: http://sqlfiddle.com/#!2/8148be/3 How can I find the first user who has reached a total saleValue of 30 since the beginning of ...
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3answers
192 views

Will redirecting queries to dev/null warm up indexes?

I'm trying to warm up the buffer pool. Will running a query and re-directing the output to /dev/null suffice? e.g. mysql -u username -p -e "select id from tbl where 1=1" > /tmp/results.txt Thanks
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1answer
2k views

column auto updated after 24 hours in mysql

i have a table T1 with column : Name State time mon 1 2014-01-09 11:23:00 tue 0 2014-01-07 14:40:00 wed 2 2014-01-08 09:23:00 thu ...
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1answer
52 views

How are these two user drops different?

Other than the obvious, what is the difference between: drop user user_01@host01; and drop user 'user_01'@'host01'; In a sample test, they both achieved the same result. From Account Names docs ...
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1answer
571 views

How to set unique columns combination

see this table: CREATE TABLE IF NOT EXISTS `default_messages_users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `message_id` int(11) NOT NULL, `owner_user_id` int(11) NOT NULL, `to_user_id` ...
1
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1answer
760 views

Change root password of mysql database

This could be a Rookie problem , but it seems that i am not able to solve it. I have MySQL server installed on my windows machine(MySQL 5.5) under the Admin username root. Some How i lost the ...
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1answer
718 views

when will Innodb support activation of triggers on cascade foreign key? [closed]

The Manual says: http://dev.mysql.com/doc/refman/5.6/en/innodb-restrictions.html Currently, cascaded foreign key actions do not activate triggers. Any Idea when will this be implemented. Is ...
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3answers
251 views

getting error while starting memecached service with ndb engine

i am installed memcached library by following the steps in the internet. now there is a binary file created in bin folder of mysql now i exicuting the command memcached i am getting error like this ...
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1answer
106 views

MySQL Latest Deadlock Explanation

Can someone explain this deadlock to me? It seems as if there are 2 inserts happening within milliseconds of each other with the same Primary Key. I'm not sure how this can cause a deadlock. At most a ...