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

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180 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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290 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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68 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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715 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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55 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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80 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
83 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
143 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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35 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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104 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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167 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
384 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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924 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
303 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
1k 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
5k 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
330 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
101 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
84 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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194 views

What is the ideal connection pool size for RDS MYSQL?

I have a tomcat server hosting REST APIs. It is connected to a MySQL (RDS Instance) server on the backend. A majority of the operations are write operations (Around 75%). I'm using the Tomcat's ...
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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. ...
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2answers
1k 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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220 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
74 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
57 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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90 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
63 views

Get rows in a range of time

I have a table with two columns that stores TIME type values. This is the CREATE statement: CREATE TABLE `sdriving_turno` ( `idturno` bigint(20) NOT NULL AUTO_INCREMENT, `idempresa` int(10) ...
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2answers
148 views

avoiding unique key collisions across tables

This might be related to the idea of data warehousing, but i'm not sure, though it is extreme theory. We have a table where records get written to first, let's call it tbl_recording which looks like: ...
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1answer
465 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
424 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
220 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
1k 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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960 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
193 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
5k 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
110 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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37 views

Is there any way to set server-wide and schema-wide default row formats for InnoDB tables in MySQL?

Is there a way to set server-wide and database-wide default row formats? Currently it seems that I must specify ROW_FORMAT in CREATE TABLE or ALTER TABLE statements. Am I reading the documentation ...
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95 views

How to set up a pivot table view?

I have three tables: Entry Manager Employee The Entry table has as date field and a bunch of other fields about the entry including the emp_id. Manager Table has columns: Manager_id ...
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367 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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25 views

Anyone know the fix for an older innodb inspection query

This post talked about an information_schema query to give you a nice report of how much percentage wise indexes are fitting into the buffer pool The query looked like > SELECT `schema` ...
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2answers
543 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
740 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
80 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
207 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
4k 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 ...
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94 views

How to prevent Cartesian joins when value can be in either field?

I have a table of articles where the same article may be presented to different audiences with slightly altered text depending on the user's access level. When this occurs, the article will have the ...
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1answer
98 views

Change normal user to admin in MySQL

I have set up a MySQL database. My problem now is I can't add new users with the user I have created. I try to grant access but I can't still add new users to my system. I use Workbench to add new ...
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1answer
32 views

Count issue in Mysql

I query a table SELECT COUNT(*) FROM sf_guard_user_group return count 1 but table has total 28 records. But if I test it via putty from another machine, it shows count 28. Help to sort out.
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1answer
2k 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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123 views

how to update current row value by selecting previous row value in php mysql

How can i update data of current row with selecting data of previous row in php mysql. I have tried following query but it showing me error. update sales_tracking set sales_tracking.opening_units = ( ...