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

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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
97 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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2answers
533 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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0answers
121 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 = ( ...
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1answer
35 views

Cannot create stored procedure

I have the following piece of statement entered into MySQL5.6 Command Line Client. However, the following error was received. I haven't even been able to add in END// Delimiter; after the select ...
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40 views

How to move partitions between filesystems

We have ~9TB MySQL database which consists from a few tables which are partitioned by day. Sum of daily information is ~20GB. Database is practically write only. There are at most tens of queries ...
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22 views

Cloning rows with minor changes

I am attempting to clone a row in the database, not that difficult. However the row has a reference to another row in the database that when inserted needs to use a different value, perhaps provided ...
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28 views

Accessing Database from Slave server

I have an application running in one server eg: My Server's Ip is 192.168.10.10, and I have the MySQL database server in the same machine. The application connects database server as localhost. ...
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1answer
162 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 ...
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1answer
44 views

Unknown column error with an index

I created a simple index associated with a timestamp column CREATE TABLE `data` ( `id` INT(11) UNSIGNED NOT NULL, `ticker` VARCHAR(16) NOT NULL COLLATE 'utf8_unicode_ci', `comment` TEXT ...
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1answer
537 views

Possibilities to speed up InnoDB INSERTs and UPDATEs

My website retains user sessions in an innodb table. This usually works well, but a few hundred times a day, the INSERT and particularly the UPDATE statements run slower. I'm monitoring when, and it ...
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1answer
83 views

How to drop a column named 'column'? [closed]

I need to delete a column named "column" form a table but the standard: mysql> ALTER TABLE table_name DROP COLUMN 'column'; returns: ERROR 1064 (42000): You have an error in your SQL syntax; ...
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1answer
88 views

Using an enum index to limit records

A common issue, just not sure on the keywords. I have a table of assessments (14k+ records). Each assessment can be in many different states ('draft', 'proofing', 'amends', etc... and 'done'). Most ...
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1answer
136 views

MySQL 1366 Error on Replication Slave

I've got two pairs of servers (each identical hardware and OS) with replication running on both pairs. Running MySQL 5.5.34 on Windows Server 2008 R2. I'm trying to track down a problem that has ...
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1answer
76 views

How and where do I upload a mysql database?

I am new to Ubuntu (server edition) and mysql. How do I upload (import) an existing database with a MYSQL or (mysql.zip) extension that was downloaded from a web host (cPanel?) I do not have any of ...
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2answers
265 views

How can I return column names in dot notation in MySQL?

I want to return column names into a table. But I also want to avoid redundancies like 'id' and 'id'. I did: INSERT INTO columns(name) SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE ...
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1answer
121 views

Is there a way to achieve Workload Management in MySQL?

Is there a way to set up Workload Management in MySQL (in particular v5.5 on AWS RDS)? By Workload Management I mean the functionality implemented in e.g. Teradata, RedShift that allows ...
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117 views

Booted by MYSQL Error (2003) 10060 mid way through work

I was working on some queries and then my HeidiSQL froze, I tried to reboot the connection and I get good old MYSQL Error (2003) (10060). It worked just fine before that. I haven't made any firewall ...
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1answer
84 views

how auto_increment work in mysql

im confused here , i create a table and have 2 columns id and name. Now id is primary key , not null and auto increment. Suppose i fire: insert into table (name) values('test'); this will give me: ...
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1answer
1k views

MySQL: Alter Table on very active table gives “Waiting for table metadata lock”

At my work, we've recently upgraded to MySQL 5.5 and since then, have been bitten a few times by the new (and intended) behavior of metadata locking. Basically, whenever we run an ALTER TABLE ...
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1answer
289 views

How to update a table by count from another table?

I have two tables as CREATE TABLE country_statistics ( id int(11) NOT NULL AUTO_INCREMENT us int(11), uk int(11), ca int(11), PRIMARY KEY(id) ) ENGINE=InnoDB DEFAULT CREATE TABLE entries ( id ...
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1answer
52 views

MySQL Partitioning: why it's not taking appropriate partition

DROP TABLE temp; CREATE TABLE `temp` ( `CallID` bigint(8) unsigned NOT NULL, `InfoID` bigint(8) unsigned NOT NULL, `CallStartTime` datetime NOT NULL, ...
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42 views

Is it better performance wise to check if a field needs update if you know the record does

In the queries we use all the records in one table that has data which needs to be placed in a another system had a Insert, Update and Delete flags (i, u, d being 1 in the record), this way we can ...
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76 views

Query Execution Plan for MySQL

In Microsoft SQL Server you can see Execution Plans for queries to see how a query is executed, what joins take the most time and see any missing indexs now i want to do the same for MySQL scripts ...
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1answer
59 views

Create user for alternate port

I am running a private MySQL instance on WebFaction WebFaction is a shared host who provides both for their public MySQL instance and for your own private MySQL instance. The private instance is a ...
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4answers
2k views

MySQL gives me:“Can't open and lock privilege tables: Table 'host' is read only”

I am facing problem restoring a MySQL database. My primary database was MySQL 5.1 and now I am trying to copy it to MySQL 5.5. The database was backed up by using Xtrabackup. I am using Ubuntu ...
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0answers
307 views

mysql doesnt have write access in data dir?

I am running a MySQL on my Windows 7 64 bit development machine at work and I can't seem to get around a database corruption issue. In my unit tests it is telling me that the storage engine (which is ...
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2answers
371 views

How to use OR in query with priority?

In a simple query like SELECT * FROM table WHERE id='x' OR id='y' How to give a priority to get only one of the WHERE clauses? I mean getting rows with id='x'. Only if there is no row, get row ...
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1answer
96 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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1answer
49 views

Join on with modified ON

I am trying to create table with summary of few other tables. All solutions i came up with are very slow and clearly not optimal. Initially I tried with multitude of subquerries but that was very ...
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30 views

table scheme definiation it this way that insert duplicate into another table

I have a table in which there is a column name with SP varchar(10) NOT NULL. I want that column always to be unique so i created unique index on that column . My table schema as follows : CREATE ...
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1answer
2k views

Upgrading MySQL 5.1 to 5.5 on Centos 6 without removing dependencies

I'm trying to upgrade MySQL 5.1 to 5.5 using yum/rpm combo (yum to remove MySQL 5.1 and rpm to install MySQL 5.5). Most instructions I've found suggest to do first: yum remove mysql mysql-server ...
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305 views

Incorrect information in .frm file after a power outage?

CentOS release 6.3 (Final) x86_64 mysql Ver 14.14 Distrib 5.5.31, for Linux (x86_64) using readline 5.1 SHOW SLAVE STATUS\G: Slave_IO_Running: Yes Slave_SQL_Running: No ...
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0answers
382 views

MySQL InnoDB slow inserts

I'm currently struggling with an MySQL Community Server 5.5.27 when inserting large numbers of rows into a table. We're running a 24 core Intel Xeon machine with an SSD software raid array. I did some ...
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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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1answer
4k 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 ...
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1answer
1k views

Recover the disk space after deleting rows from table

I deleted millions of rows from one of the table with innodb engine. I know that I need to run optimize table to recover the space. But running that will cause lock on the table, which will affect the ...
2
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1answer
235 views

MySQL / Fusion IO Configuration Question

I need a little configuration optimization. I think what I have is pretty good but feel like there's still room for improvement. Current Config [mysqld] user=mysql datadir=/var/lib/mysql ...
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21 views

How do I configure MySQL to store specific entire InnoDB tables on a different drive in Windows ( Server )?

After skimming the MySQL ( 5.5 ) docs on Partitioning, that seems to deal with breaking parts of the same table off onto other drives. I'm struggling to find information on how I pinpoint an ...
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1answer
150 views

Restrict access to rows by usename

In my database i store data of different users (e.g. addresses or invoices) in the corresponding tables. I want to make sure that a logged in user only has access to it's own data in the tables (so ...
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1answer
50 views

Optimizing a union query

SELECT id FROM user WHERE id IN ( 2,3,4,7,9,21,23,45,324,12,43,254 ) UNION SELECT DISTINCT user_id FROM workgroup_users WHERE workgroup_id IN ( 1,345,34,654,213,123,5,2,3,4 ) I know we should not ...
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1answer
94 views

Whether or not to create separate tables

I am working on a project, where I need to store the information related to A and B, the A and B both have identical columns.There might be thousands of As and Bs. Should I use "type" column to ...
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1answer
5k views

How to get MAX and MIN in GROUP BY query?

In a simple query SELECT col1, col2, col3 FROM table1 GROUP BY col1 each row includes the first value of col2 and col3 for each unique value of col. How to select MAX and MIN for each value of ...
2
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1answer
85 views

Need to Rewrite/optimize Slow Query

I have a query with following explain plan EXPLAIN SELECT COUNT(applicant.id) as applicantCount, application.name,applicant.application_id,application.id FROM applicant LEFT JOIN application ...
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57 views

Is using “read-committed” isolation level save on *slave*?

I saw a few articles which discuss how different transaction isolation levels affect replication. If I understand properly, all these related to transaction isolation settings on master, not on slave. ...
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62 views

Percona mysql server slow queries

Recently I bought new database server and installed percona mysql server 5.5.32-31 and transferred my /var/lib/mysql directory from old database server having Percona mysql server 5.5.28 to new ...
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3answers
696 views

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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3answers
204 views

Why set up static data in views vs. using tables in mysql?

I get an LDAP feed nightly. I get it as a text file and dump/create my LDAPALL table. There are roughly 75K employees times about 50 fields. I have the following too: LDAPIMPORTANT - view that ...
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415 views

SELECT + INSERT + Query Cache = MySQL lock up

MySQL server seems to constantly lock up and stop responding on certain types of queries and eventually (after couple of minutes of not responding) give up with an error "MySQL server has gone away", ...