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

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MySQL - grant all privileges on *.* brings back Access denied

GRANT ALL PRIVILEGES ON *.* TO 'username'@'localhost' IDENTIFIED BY 'somepassword'; Brings back error : ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) If ...
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1answer
45 views

Different column for different conditions when joining

I am using MySQL database and in that two tables, relation is one to many. One table is product table, sample data: +----+----------+ | id | name | +----+----------+ | 1 | product1 | | 2 | ...
2
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1answer
28 views

WHERE attribute having two relation lines in the same SQL

I have a database designed with tree tables: checklist (id, name) tag (id, name) checklist_tag (checklist_id - FK, tag_id - FK) Running this SQL: SELECT cc.id as checklist_id, cc.name as ...
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2answers
30 views

Mysql replication with c

I have huge database on MySql and It's become more and more huge. So, Now I am facing performance issues with my database. Some of tables has millions of records in it. like my login detail table ...
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2answers
51 views

Database Design Help: MySql/PostgreSQL Single Database/Multiple Databases

We are planning to build a web based custom business analytics tool using PHP and MySQL/PostgreSQL. In our application, we are planning to upload customer’s data using a Excel sheet and these data ...
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1answer
28 views

mysql server is not starting

mysql server is not starting after modifying configurations key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 query_cache_size = 16M after ...
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1answer
18 views

How can I tell when InnoDB recovery is complete/check its progress?

I'm writing a process to bring up a new instance from our nightly database snapshots, and I want to watch its progress and perform some actions once the database is up. When mysql first comes up, it ...
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0answers
38 views

amazon small instance mysql query too slow

I have mysql database with 1.5 millions records with 2 million categories records. when i do query on categories and city where clause it takes 304989 milliseconds. on localhost it too fast. i tried ...
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2answers
35 views

query execution time in mysql

I have run the query in mysql which consists of approximately 33million records when i have executed the query select population1 < 200000 from city; it shows like this after execution ...
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1answer
16 views

change character set in mysql permanently

I want to change following parameters to utf8mb4 so that mysql can store emoji characters and special language characters. but when i try running following statements one by one SET ...
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1answer
35 views

unable to import the file

Gone through the below link also but i am unable to import CSV file in mysql. Even i had tried by using > LOAD DATA LOCAL INFILE but same error persisting. Please help me in this. queries i tried had ...
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2answers
28 views

MySQL query performance question

I have a MySQL database where I would like to return results based on multiple rows. id | key | value | selector --------------------------------------------------------- 1 | username ...
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2answers
32 views

Using a join to return multiple values of the same column?

I have two tables user Rank In the Rank table, I saved rank_id and supervisor_id. In the Rank table, I stored the rank name. The rank_id and supervisor_id are foreign keys from the Rank table. ...
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1answer
36 views

Btree index and Bit Map Index [duplicate]

Please clarify the difference between BitMap Index and Btree index. I am using mysql version 5.5.37-0ubuntu0.12.04.1. I can able to create Btree index but unable to create the same, Please find the ...
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0answers
9 views

Archive storage engine

What is main difference between innoDB and Archive storage engine. which storage engine is best for using an application which will have n No's of data to be passed daily? Please suggest
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1answer
19 views

installing mysql 5.1 alongside mysql 5.5

mysql 5.5 is installed. I need 5.1 to install an old website so it can be updated. The installer refuses to let me install onto the disk with 5.5. I don't have any other disks. I downloaded the ...
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1answer
40 views

Could not access database

I have been trying to setup a local instance for a new application. I am new to MYSQL and I cannot understand how to actually connect this database to the actual web application sitting in the ...
0
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1answer
13 views

mysql fulltext query is very slow

I have one table for User detail in MySql with about 500000 records in it. I have also created fulltext index on firstname, lastname field on this table. but when I am trying to search any single ...
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2answers
20 views

getting one day timestamp in mysql

Please consider the following stored procedure I have: ORIGINAL Stored Procedure: -- -------------------------------------------------------------------------------- -- Routine DDL -- Note: comments ...
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1answer
20 views

MySQL Database Memory Consumption

i am newbie in mysql, just want to ask if what is the right formula in computing memory allocation for mysql, and how to check/query mysql memory consumption or we say where does memory consume by ...
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1answer
37 views

How performance schema in mysql 5.6 improve performance?

Since MySQL 5.5 performance_schema database has been added likewise information_schema. As we know that tables in information_schema contains statistical information like tables, plugins, partitions, ...
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2answers
62 views

Are there benefits to using more than 4 CPUs for MySQL?

We are running MySQL 5.5 on linux under VMWare, running on 2 CPUs. We are planning on increasing this to 4, but we have un-used CPUs available, and I'm wondering if there is any benefit to increasing ...
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1answer
24 views

Setup mySQL in a chroot in Debian Wheezy

Sounds like a simple question, but the documentation is rare about what mySQL needs to run inside a chroot. I think I'm almost there, but I'm running into a permission problem that I can't solve, and ...
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0answers
29 views

MySQL 5.5, Xubuntu 14.04 - INSERT and UPDATE bottleneck

DBAs: I have been developing and maintaining plugins for Moodle for the last ~2 years, and have recently decided to try using my local desktop again, rather than my institutions ESX VMs, as a ...
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2answers
59 views

How to monitor InnoDB Disk I/O using Server Status Variables?

This question is extension of my previous question "How to monitor InnoDB Disk I/O Required for MySQL? " As mention in my previous question i want to count total number of disk i/o per query, but ...
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1answer
40 views

Safely changing innodb_buffer_pool_size on MySQL replication master?

We have a MySQL server which is a replication master. We need to change the innodb_buffer_pool_size and innodb_flush_method to (hopefully) improve performance as the database has grown. What is the ...
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1answer
36 views

How to log within a stored procedure that is encapsulated within a transaction

I have a stored procedure, let us call it sp_A which calls other stored procedures, let us call them sp_B and sp_C. For the sake of consistency an XA TRANSATCION is started within sp_A. What I ...
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1answer
52 views

Dedicated mysql server slow response [closed]

I have server in Kimsufi with 2gb RAM but my server is very slow , with simple hosting in ovh it responds quickly ... With pingdom.com test i have for server: 10 sec and simple hosting: 2sec is ...
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1answer
36 views

How to Reclaim Data Free in InnoDB Tables?

I came up with an idea on how to shrink ibdata1 in mysql database then i got this solution on stackoverflow STEP 01) MySQLDump all databases into a SQL text file (call it SQLData.sql) STEP 02) Drop ...
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1answer
28 views

Two MySQL requests at the same time - Performance issue [closed]

I have a MySQL server with many innodb tables. I have a background script that does A LOT a delete/insert with one request : it deletes many millions of rows from table 2, then insert many millions of ...
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73 views

What to do with unused RAM on a MySQL database server?

For years I have been running dedicated servers with more or less limited ressources, resulting in unsatisfying performance of the web application (Drupal). Tools like Matthew Montgomery's MySQL ...
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0answers
16 views

output from mysqltuner.pl (from mariadb.service)

While running mysqltuner.pl script, I'm getting following message: [OK] Currently running supported MySQL version 5.5.35-MariaDB-log [OK] Operating on 64-bit architecture -------- Storage Engine ...
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0answers
15 views

mysql service failed to start when datadir changein ubuntu

I have dual Operating system on PC, windows 8 and ubuntu 14.0, and I am mostely using ubuntu because my MySql database is hosted on ubuntu. Recently when I am trying to restore my database, which is ...
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1answer
13 views

What should I do if i forget password in MySQL?

I am using MySQL5.5. I trying to login in mysql from terminal by using "sudo -u root -p" But i could not remember password. How can i fix this problem?
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1answer
39 views

Mysql improve Self join performance large table?

I have a task to help identify conflicting IP ranges , I want to highlight when one companies IP range falls within another's ... below is the sample table, I have converted the IP ranges from .dot ...
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2answers
50 views

MySQL Community Edition Capacity

I am using MySQL Community Edition on Amazon RDS service. It is a very large database, 2/3 tables has about 10 millions records and 4-5 tables has 7-8 millions records. Questions How much capacity ...
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0answers
9 views

A connection is in sleep for long time in MySQL

When I am looking in process list, three to five sleeping connections are alive. I can kill them but except one connection that is first one in above image. A user connected with information_schema ...
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0answers
7 views

Recovery database from masters

I have a multi master setup with 3 mysql nodes with Tungsten, Unfortunately replication has broke between 3 servers. Now the data is inconsistent say 100 users data is in node1, 100 users data in node ...
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0answers
24 views

tables don't exist after unmounting and remounting external drive where database was installed

I want to create a database that's too big to keep on my own machine, so I'm trying to create one on an external hard drive. It works up until I unmount and remount the drive, at which point show ...
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2answers
36 views

MySQL user without SUPER privilege

This may be a simple question and may not be the right place to ask but I couldn't find any useful information from Google. Here is my question. When creating users in mysql using grant all ...
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1answer
23 views

ON DELETE CASCADE pseudo delete

For data integrity ON DELETE CASCADE is necessary but it's really dangerous when a delete affects like a Chain Reaction! I know one way to prevent this is to make a pseudo delete by putting a ...
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1answer
38 views

Select post and concatenating all categories it belongs to

I have 3 DB tables POSTS +----------+----------+----------+ | id | title | content | +----------+----------+----------+ CATEGORIES +----------+----------+ | id | title | ...
2
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4answers
223 views

Aggregate query optimization

Could you please help me to optimize this query - currently it takes ~4 minutes to run this query. It looks like keys: ip and timestamp are non-unique so shall I add some indexes? mysql> EXPLAIN ...
1
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1answer
62 views

Master-Master Replication Duplicate Key

I have set two servers master-master replication mysql , i manage to set successfully but the problem is the duplicate key i got MASTER 1 Configuration /etc/my.cnf [mysqld] server-id=1 bind-address ...
0
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1answer
58 views

want to download 3GB database table from my development mysql server [duplicate]

I need to download database structure with data. Total size of the DB is more than 3GB. If i use phpmyadmin it is not working. I have also tried by increasing the execution time in php.ini. I need ...
0
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1answer
57 views

Whether to use or not to use: DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

In one Database table, created_at & updated_at are defined as: `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP `updated_at` timestamp NOT NULL DEFAULT ...
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1answer
46 views

Query to retrieve data based on several where conditions ( Not off Topic , Answer provided below is right ) [closed]

Database : Mysql 5.5 i have a table T1 containing 4 columns : No. , Height , start_time , end_time In column height i have 3 distinct values only : Small Medium High Now i ...
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21 views

Rails with mysql 5.5 update queries take long

app was running Rails and MySQL 5.1 and worked quite well. When we have upgrade to the new server with MySQL 5.5 some update and delete queries started to work quite long (1 sec vs 50ms on old ...
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22 views

Log-slave-updates in multi master replication using Tungsten replicator

I m setting up a system as follows with 2 masters and 2 slaves. M1 <----> M2 (Tungsten Replication) M1 ----> S1 (MySQL Replication) M1 ----> S2 (MySQL Replication) I have enabled the ...
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Refactoring IN Subquery, Avoiding Query in a Loop

I've got a table which was designed as both the current data set for participants, as well as being the historical changeset for those participants. This table has been in use for approximately three ...