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

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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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2k views

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
63 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
102 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
90 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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267 views

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
173 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
383 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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3answers
2k views

Amazon RDS MySQL performance issues

I have published my website on Amazon EC2 (Singapore region) and I have used MySQL RDS instance for the data storage. Everything is working very fine except performance. It seems that all queries, ...
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2answers
115 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) ...
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2answers
96 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
70 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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1k views

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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1answer
1k 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
88 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
4k views

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
65 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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143 views

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
125 views

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
351 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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0answers
57 views

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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183 views

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
391 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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2answers
741 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 ...
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1answer
3k views

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
412 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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2answers
4k views

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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2answers
7k views

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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1answer
738 views

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
187 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
144 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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2k views

Does a TRIGGER improve the performance?

I understand that TRIGGERs are useful, as they take care of subsequent queries, but do they have an advantage from performance point of view too? Replacing two or three queries as INSERT INTO table1 ...
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2answers
607 views

Warning before issuing delete/update command in mysql/oracle , then executes

Is there any utility , function either in mysql /oracle that if i issue some delete/update command wrongly , a message must prompt at command_line* (if possible in ubuntu) asking whether "you sure to ...
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1answer
121 views

addition in datetime column during insertion in mysql

i have a table with below 5 columns..timestamp is data type for timedate related column : Region event_time start_time mid_time end_time India 2013-11-03 13:00:00 America ...
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1answer
82 views

MySQL geospatial query optimisation suggestions

I am new to DB Administration. Trying to sort out this query which is the heart of our application. I am searching google on similar questions, but would like an experts opinion on my particular ...
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97 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 ...
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1answer
941 views

Timeout on ALTER TABLE table ENGINE=InnoDB - is table still converted?

I'm converting tables in an old MYISAM database to InnoDB to increase robustness in case of power loss etc. I'm using Mysql 5.5.x Before doing the production system, I am doing a trial run on a copy ...
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3answers
939 views

Converting live MyISAM table to InnoDB

I have a table that tracks web traffic. The table is constantly written and read from. Since table is pretty big in size I have to make sure the application will not "freeze" in the process of ...
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1answer
709 views

Datetime Difference in MySQL when format is Varchar

I have two columns in a table: STOP and START, of type varchar. I want to have the difference between both columns, and I'm using : SELECT DATEDIFF(stop, start) AS difference from T1; It is ...
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2answers
3k views

What is the difference between NULL and \N while loading data from a csv using load data local infile

I have a table which has four fields create table test_hc1(cola int,colb int,colc varchar(20),cold int); Now, I am trying to load following data 1,2,\N,4 and the third field in table is coming ...
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1answer
2k views

MySQL - Server collation utf8_unicode_ci vs table collation utf8_bin: compatibility and performance

I'm not sure whether this belongs to SE DBA, but it sounds more logical ... Our MySQL 5.5.32 on Ubuntu 12.04 64 uses utf8_unicode_ci for the Server collation and some tables, like phpBB3, uses ...
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1answer
237 views

Squeezing Maximum Out Of My Server

I have a dedicated server only built to hold MySQL databases. Currently I have a database that has 173 million records and increasing by 5-15+ million records very day. My question is what and why I ...
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2answers
8k views

What max_allowed_packet is big enough, and why do I need to change it?

I have MySQL (5.5) in master-slave setup and created another slave server. I stopped the original slave, dumped the data, copied and reimported and it worked fine. I noted the master_log pos of the ...
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1answer
349 views

Update the host field in Grant privileges in mysql

I have an existing table and I want to update host part in privileges using Grant command mysql> show grants -> ; ...
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0answers
806 views

Fastest way to perform simple operations on 1 million rows

I have a simple table with more than 1 million rows in an InnoDB MySQL table. Here are the steps that I need to perform on each row: SELECT * FROM tbl where work_done=0 make some data processings ...
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2answers
1k views

How to enable the Federated/FederatedX storage engine on MariaDB 5.5?

I upgraded from MySQL 5.1 to MariaDB 5.3 and then to 5.5 on a Windows machine. Everything works well, except I can't enable the federated storage engine. With MySQL 5.1 and MariaDB 5.3, I just added ...
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2answers
1k views

Fastest way to change a 600GB table indexed key datatype from INT to BIGINT

I need to change a datatype from INT to BIGINT in a 600GB MySQL table. The column has a unique index. I might be good with unsigned INT, but I assume changing to that or BIGINT will be pretty much ...
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1answer
162 views

How to make slave is in sync with master in tungsten replication?

we are using Tungsten master to slave replication in MySQL. we have configured this setup very long back. from last week onwards slave is in lagging with master around 5 to 10 binary files. we have ...
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1answer
505 views

Replication - Binary log parsing(Tableid generation, ON DELETE CASCADE handling, Changed columns for update event)

I am using MySQL 5.5 with InnoDB engine. I have set binlog format as row-based replication. I have some doubts regarding replication: 1) How is the tableID generated? Is it stored somewhere? 2) ...
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1answer
5k views

Function returning “No data - zero rows fetched, selected, or processed” in MySQL 5.5

I have upgraded MySQL version to 5.5.16 After upgrading, some of the functions are giving warning as No data - zero rows fetched, selected, or processed. In those functions, cursors are there, but ...