MySQL version 5.5 - please also tag with mysql for search purposes.

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MySQL varchar(255) limitation & Anomaly

I have defined a column in my MySQL database as : ALTER TABLE `my_table` CHANGE `desc` `desc` VARCHAR( 255 ) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL However, when I enter text ...
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Contains statement Query

I need to check the string with the column if the column contains that string or not. example:String 'how to make pizza' and the column if has 'pizza' i need to fetch that.. like SELECT * FROM ...
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114 views

MySQL query with order by decreased performance

Here is my schema: CREATE TABLE `UserMst` ( `UserID` mediumint(8) unsigned NOT NULL AUTO_INCREMENT, `EMailID` varchar(50) DEFAULT NULL, `UserName` varchar(20) DEFAULT NULL, `FullName` ...
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Backup / Export data from MySQL 5.5 attachments table keeps failing!

Can anyone please help! - I have a large table in a MySQL 5.5 database. It is a table which holds a mixture of blobs/binary data and just data rows with links to file paths. It has just over a million ...
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1answer
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InnoDB - How to get top locked tables and rows which are locked

I was searching for a tool OR query which can give me top locked tables and which particular row is locked, Is it possible to get ?
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69 views

Check whether MySQL Innodb Rows are compressed

After setting the various variables to enable compression on the Innodb Barracuda tables, what query will you use to check that those tables are indeed compressed?
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Performance with IN clause

Does indexed data affect query performance? means If I passed value as 1,2,3,4... in ordered form in any IN clause, can it improve query performance? and what happen in case I pass value randomly ...
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1answer
505 views

XML dump of MySQL database don't include foreign key constraints. What can be the reason? sqldump(.sql) file list it

I am accessing schema information of databases in XML format. I am taking dump of the database in XML format using the command below. mysqldump --no-data --xml -u root -p bakerydb > bakerydb.xml ...
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1answer
701 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 ...
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crossplatform mysql_install_db script in mysql 5.5.34 on Windows

I downloaded mysql-5.5.34-win32.zip and found out there is mysql_install_db.pl script. However mysql 5.5 documentation says: mysql_install_db is a shell script and is available only on Unix ...
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1answer
231 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) ...
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3answers
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Why does InnoDB store all databases in one file?

It was convenient that MyISAM used to store each table in a corresponding file. InnoDB has made advancements in many aspects, but I wonder why InnoDB stores all databases in one file (ibdata1 by ...
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2answers
903 views

MySQL Synchronous Replication on Ubuntu 12.04 with DRBD

I have been looking around for some easy and open-source ways to handle database synchronous replication. DRDB on a Linux server seems to be one of the fastest and easiest methods to handle database ...
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0answers
556 views

Upgrading from MySQL 5.5 to 5.6 - timestamp issue?

I'm looking at upgrading my Percona Server setup from 5.5 to 5.6. Reading the upgrade docs from MySQL sounds mostly straightforward except for anything involving time/date columns. As far as I can ...
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2answers
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Cannot stop MySQL 5.5 replication threads

We have a master-master replication setup using MySQL 5.5. On one of the servers I am trying to stop the slave thread, but without success. To ensure that the replication does not connect to a real ...
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2answers
899 views

MySQL replication: slave not updated

This has been asked many times over but we really cannot get a simple Master-Slave Mysql (5.5.25) replication to work for our two dbs (FatTree and Torus). And no trace of error in the logs. The ...
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1answer
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How to create trigger to update timestamp when record is updated or inserted in another table

I have a table t_task and a table t_taskaction with a foreign key to t_task. I would like to update timestamp from t_task that is refering the foreign key form t_taskaction with every update in ...
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mysql forbidden database names

I was wondering whether there were a list of forbidden (reserved) database names in mysql. For instance, mysql is obviously one. But is there a determinated list? I don't want to cover 99% in my ...
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1answer
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Database design [closed]

I have tables college and department. In college, I have serial-number and college-names, In department, i have nos, college-names and department-name. My challenge is that having a repeated ...
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458 views

Help my database isn't performing fast enough! 100M Merge with 6M need < 1 hour!

I have a server right now receiving more raw data files in 1 hour then I can upsert (insert -> merge) in an hour. I have a table with 100M (rounded up) rows. Table is currently MyISAM. The table has ...
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143 views

Mysql query getting hung!

I am using mysql 5.5. I create following temporary table: CREATE TEMPORARY TABLE IF NOT EXISTS tempdb.%s ( `count` int(10) NOT NULL, `m_class` enum('SMS','EMAIL') NOT NULL, ...
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2answers
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Trouble with triggers and insert .. on duplicate key update

I have two tables with identical schemas. one is a "main" table that is pruned periodically and kept small. The other is a "reporting" table that is an archive of everything that ever was. For ...
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1answer
81 views

Poor query performance in MySQL

I have a 10 million record table in a MySQL 5.5 InnoDB. It's running in a 16GB RAM server with good CPU and fast HD. When I run the following query SELECT DISTINCT knowledge_id, ...
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1answer
141 views

Slow MYSQL performance due to sub queries

Here is my query: SELECT BAL,NAME, (SELECT SUM(DR) FROM transaction WHERE NAME=TNAME AND DATE < '2000-05-01') AS DR , (SELECT SUM(CR) FROM transaction WHERE NAME=TNAME AND DATE < ...
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1answer
399 views

Annonymous user has no privileges, but still able to show databases?

Output of SHOW GRANTS FOR ''@'localhost'; GRANT USAGE ON *.* TO ''@'localhost' However, when I log in using my default user account, which is later defaulted to an annonymous account by mySQL as ...
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Alternative to TEMPORARY tables capable of re-opening in a query?

I use TEMPORARY table for calculation of temporary data, but TEMPORARY tables in mysql has a big limitation, which made it useless for me. A table cannot be re-opened in a query. This mean I cannot ...
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1answer
276 views

How to UPDATE MAX and MIN of a GROUP BY?

I have a SELECT query of a table with GROUP BY id col1 category 1 some 1 2 x 1 3 another 1 4 x 2 // should be removed 5 some 2 6 x ...
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1answer
648 views

Use string functions and arithmetic calculations in SQL query or by programming language?

I need heavy arithmetic and string functions for processing the data captured from mysql database. Which is preferred: mysql functions or programming language (e.g., PHP)? $result = ...
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2answers
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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) ...
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2answers
178 views

Grant access on a database to all users

I have a global database, as I all users should have access to it. Is it possible to grant permission on a database to all users? something like GRANT ALL ON my_database.* TO *@localhost; Even (for ...
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1answer
101 views

How can I efficiently search for all records from a given month, or a given year?

We have a couple queries that involve datetime fields. In particular, we are checking for things like SELECT field1, field2, ..., field20 FROM table WHERE MONTH(startDate) == 1 SELECT field1, field2, ...
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1answer
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How to use LOW_PRIORITY for heavy queries?

I have scheduled heavy UPDATE queries at administrator level, and since they are heavy UPDATEs with multiple JOINs, consume a huge amount of resources. I do not want them to stop end users from ...
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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
112 views

Query result set

I've 1 query written in our legacy system. (using MySQL 5.5) Now, with growing data - the below mentioned query taking huge time. In our system, we've somewhat 2,000,000,000 (2 billion rows) approx ...
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1answer
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MYSQL - Problem with foreign keys on same table

In Mysql 5.5, I have a table, in which I store some informations about "events".. In order to have a chronological order, I made two columns that reference to the previous and to the next event. So I ...
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1answer
91 views

Few Insert queries rollbacked due to system crash

Well, this problem occured to me first time. Yesterday, one of our mysql system server crashed and when it restarted last few inserts were completely rollbacked. I am sure that they were proper ...
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Cannot find /etc/init.d file in opensolaris

While installing MySQL , I noticed a point, I mean to start the MySQL server manually , use the command cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysql The error shown is : cp: ...
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2answers
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Indexes slowing Insertions(Can't use Explain Insert to Analyse)

I have a MySQL database, I am parsing files from a log and inputting it inside. So far including a simple 4MB file in the database could take me about 4 minutes to insert ! and i have about 10,000 ...
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1answer
395 views

char vs varchar in mysql

I was reading the book MySQL high performance, it has mentioned that : CHAR is also better than VARCHAR for data that’s changed frequently, because a fixed-length row is not prone to ...
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I can't get MySQL server to stop running

The output from MySQL Workbench when I try to stop it is: Executing '/usr/local/mysql/support-files/mysql.server stop' 2013-12-23 21:08:29 - Stop server: ERROR! MySQL server PID file could not ...
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MySQL Load Avg High — CPU bound or IO Bound or Memory Issues

We are using MySQL 5.5 and the database is approximately 10TB. The load avg is constantly high during day time. Following are the configurations and a snap shot of a 'top' command. I wanted ...
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1answer
841 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 - ...
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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 ...
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1answer
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Query State hangs on sending data

For some reason, the query state hangs on "Sending Data" (using show processlist;) and I have no idea why. This is the table creating script: CREATE TABLE IF NOT EXISTS `esp_game` ( `gameID` ...
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1answer
604 views

Unable to take backup of mysql database using Xtrabackup

I am trying to take mysql backup without any downtime but unable to take the backup using Xtrabackup . Actual Database is almost about 40+ GB in size. I am trying to first satisfy myself. Hence, I ...
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What is the meaning of tinyint(N)?

When we use an argument length with numerical data types, as far as I know this specifies the display width. I tried the following: mysql> create table boolean_test (var1 boolean, var2 tinyint); ...
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MySQL Installation error: Unable to update security settings

I tried to configure MySQL server 5.5 on Windows and this is what I get mysql-server-5.5-winx64:56 - Attempting to update security settings. mysql-server-5.5-winx64:100 - Unable to update security ...
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How to modify `proxies_priv` in MySQL

I recently received a warning from MySQL that stated: [Warning] 'proxies_priv' entry '@ root@serverdomain' ignored in --skip-name-resolve mode. I looked in mysql.proxies_priv and there is ...
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1answer
296 views

Upgrading MySQL 5.1 to 5.5 - All tables gone [closed]

I'm trying to upgrade from MySQL 5.1 to MySQL 5.5. I followed the instructions here: http://dev.mysql.com/doc/refman/5.5/en/windows-upgrading.html I also adjusted the Datadir. But after the upgrade, ...
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2answers
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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 ...