All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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Varchar index - will hashing value make it faster?

I have a VARCHAR(1000) column in a table. It will contain strings that will not be guaranteed to be unique. I have a query that searches this column as part of a WHERE IN clause, the list of values in ...
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685 views

MySQL Read Speed and Partitioning on Separate Drives

Introduction Simple project but for an heavy read load -90% reads- over a table(~20Milion Rows ever-growing where I have to boost performance and ensure response low time for read queries) that was ...
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1answer
166 views

Is there a way to recover this database (MySQL)

I did a "cold" (db offline, all filesystem files) backup of a MySQL db. I wrote the backup to an ISO image. Unfortunately Joliet filenames are not default. I didn't realize that until attempting to ...
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2answers
1k views

MySQL: CAST + SUBSTR vs. FLOOR + MOD

I have a field in a mysql database where dates are stored as BIGINT like YYYYMMDDHHMMSS (PHP: date('YmdHis')). I'm building a query, where I check the amount of rows per hour and have tried two ...
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3k views

Recursive query in mysql

I am using GetAncestry function found at this post, The problem is when I try to use it with select query Mysql hang, I am not sure why it is happens my Mysql version is "5.5.16" any help appriciable ...
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80 views

After adding a slave to Master - Master configuration, slave syncs from only one master

Futher to my previous question, Here is what we have +<------+ | ^ V | S1<---M1 M2 | ^ V | +-------+ what happens is Upon ...
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1answer
1k views

Mysqldump from the Amazon RDS

I have a Mysql database deployed on Amazon web services RDS. I am running a crontab which runs mysqldump command. The problem is it freezes the rds instance and my website will be down for more then ...
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224 views

Breaking Semisynchronous Replication in MySQL 5.5

I've set up Semisynchronous Replication between two MySQL 5.5 servers running on Windows 7. My application is running and updating the database of the master server and same is being updated in the ...
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3answers
3k views

How to avoid deadlock while updating 2 rows in MySQL

This is a interview problem: There is a perl program that updates the database, and it could run in different processes. One process may execute a transaction like: update row A -> update ...
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2answers
1k views

Mysql. Block/disconnect slow queries

I am experiencing issue. Someone 'attacked' my server: simply by searching the same phrase with multiple requests. As it is text search request and database indices are not used, the engine searches ...
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2answers
522 views

Should master and slave have same mysql version?

I have a master database running mysql 5.5.11, and I am planning to setup a new slave. I am planning to use the 5.5.30 as it is the latest version. For setting up new slave, I am copying files from ...
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395 views

Mysql Incremental Backup and point in time recovery

I'm writing a shell script using the concept of binary logs for point in time recovery. Now, the scenario is such that a full-backup will happen every alternate day and Incremental backup should be ...
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1answer
2k views

Why does MATCH() give Score 0, if there are less rows in the database?

I followed this example from the Mysql Documentation: CREATE TABLE articles ( id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY, title VARCHAR(200), body TEXT, FULLTEXT ...
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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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940 views

MySQL InnoDB locking on combined UPDATE-JOIN statements

on querying statements which contain an UPDATE combined with JOIN, we are getting the following errors: Statements writing to a table with an auto-increment column after selecting from another table ...
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1answer
1k views

Master to Slave to Slave Configuration in MySQL

We currently have 3 MySQL Servers running; the first which contains production data and is due to be retired mysqld Ver 5.5.28-0ubuntu0.12.04.2 for debian-linux-gnu on x86_64 ((Ubuntu)) mysql> ...
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2answers
12k views

Connect Error (2054) - mysql_old_password issue still not solved

i use php 5.4.3 and i want to connect to a MySQL DB remotely (php script resides on a different server than the db) with normal oop way: $mysqli = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME); ...
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2answers
2k views

How to partition the table, week-wise?

I have a table with hundreds of thousands of records. How to partition the table, week-wise? A few million rows insertion will be taking place in my table in a day.So i need to partition it weekly. ...
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2answers
6k views

Getting repeated value in a group_concat only if ids are different

I have two tables, first the table Product: id|category_id --+----------- 1 | 12345 2 | 12345 3 | 12465 And then a table activity: id|prod_id|activity_type |description ...
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94 views

Change the Existing Topology of a MySQL Replication Setup

I want to be able to edit the topology of an existing replication, is that possible? For example if I have a star topology, I want to edit it to make it a ring one. How can I do that? I'm thinking ...
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761 views

MySQL: To use MYISAM or INNODB engine? (plot twist enclosed)

We use INNODB for all of our tables, but I have one special table, a 100+ GB reference table (only read-queries against it). We are loading changes to this table in a nightly batch job using LOAD ...
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1answer
881 views

Queries getting stuck on very simple COUNT queries

process list: | 16004 | metrics | xxx:64616 | metrics | Query | 29064 | Sending data | SELECT COUNT(*) FROM Plugin where LastUpdated >= '1356856200' | ...
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3answers
194 views

Where can I learn about MySQL master/slave, master/master, or clustering setups?

What are the best resources you've read or watched about setting up master/slave or clustering for database replication? I don't know much about this. I have a database that is getting rather large ...
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2answers
4k views

Cache all mysql table

Maybe it sound's like i'm an idiot... But i'm developing app with huge db on RoR. Also i see that if i do some query and after that do it one more it is doing much faster, becouse it has been ...
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2answers
1k views

How do I remove duplicate entries in a given timeframe?

My table looks like this: +-----------+ | id | <- primary key | time | <- DateTime | row2 | <- varchar | row3 | | ... | +-----------+ I want to remove all ...
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1answer
403 views

Setting up DRBD on an active MySQL server

When it comes to setting up DRBD and MySQL, is the following possible? Set up DRBD on an active MySQL server Set up DRBD with no downtime allowed
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921 views

Slow insert with MySQL full-text index

I use a full-text index in a MySQL table, and each insert into this table takes about 3 seconds. It seems that MySQL rebuilds (a part) of the full text index after each insert/update. Is this right? ...
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566 views

MYSQL MyISAM data recovery implementation

I am creating integration into eshop script, shop is using MyISAM tables and I need to implement something like transactions in InnoDB, what I actually need is full recovery of data after modifying or ...
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1answer
352 views

What would be possible reasons for a DeadLock to occur in Mysql Database?

If some one has a Table structure some thing like this, CREATE TABLE IF NOT EXISTS `domain_source` (`nid` int(11) NOT NULL DEFAULT '0', `domain_id` int(11) NOT NULL DEFAULT '0', PRIMARY KEY (`nid`) ) ...
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3answers
640 views

query optimization for update nested query IN(SELECT

Can we optimize this? UPDATE TABLE_NOTE SET COL_NOTE_DISPLAY='BLOCK' WHERE COL_NOTE_BIBID = $projectID AND $COL_NOTE_ID IN ( SELECT COL_PILENOTEREL_NOTE_ID FROM TABLE_PILENOTEREL ...
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2answers
729 views

MySQL: reducing ibdata file size for MyISAM tables

My Question is actually very similar to this one and also includes a good answer for a case with InnoDB Engine tables: Is there any best way to reduce the size of ibdata in mysql.?, I have noticed ...
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1answer
186 views

How to interpret explain sql?

SELECT DISTINCT TB.ID, TB.Latitude, TB.Longitude, 111151.293413 * SQRT( pow( - 6.185 - TB.Latitude, 2 ) + pow( 106.773 - TB.Longitude, 2 ) * 0.988392289802 ) AS Distance FROM `tablebusiness` AS TB ...
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443 views

What storage engine should I use for this MySQL table?

I have a table where I store all the urls from my website, and I update them from time to time when a visitor enters. The primary key is the url itself varchar(255). I have set it to use InnoDB but ...
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1answer
983 views

Delete by primary key takes too long

What would make a query that deletes a row using the primary key of the table .. take too long ? This is a table with about 1.4M rows that gets .. 70%/30% read/write . I don't know where to look. ...
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26 views

JBoss/Alfresco cannot write on slave after failover [duplicate]

Possible Duplicate: JBoss don't fail over MySQL slave using datasource I'm trying to set up an high available MySQL "cluster", using a Master / Slave Replication configuration. I want ...
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1answer
1k views

Error in login in with root user in new mysql server

I've installed a MySQL server in CentOS 6.2 machine +-------------------------+---------------------+ | Variable_name | Value | ...
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1answer
538 views

Replication Broken, List Out of Sync Tables

In a master-slave setup on MySQL 5.5 on RHEL 6.1, when db replication breaks (for whatever reason), what is a good way to: check (and alert) replication is broken? get a list of tables that are out ...
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2answers
3k views

Slave settings not working

I have this machine as slave. Below is the command I ran and stuck. I done the change on the config file and set the id=2 too. Anything else I am missing here? slave start; ERROR 1201 (HY000): Could ...
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9k views

Why is this MySQL proc using cursors failing to retrieve results?

I am importing data from a third-party vendor. I have already imported their tables into my existing database. Now, I just need to iterate through each of their person records, munge it a little bit, ...
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651 views

MySQL table with multiple values in one field

I'm building a database for a real estate company. The real estate properties are managed by sales people using a CodeIgniter website. How should I proceed with the database design for this table? ...
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1answer
330 views

Why are these queries slow in some environments and not others? Can we fix their performance?

The following stored procedures in a MySQL 5.x environment: DELIMITER // CREATE PROCEDURE sp_belongs_to (IN schemaName VARCHAR(100), IN tableName VARCHAR(100)) BEGIN SELECT TABLE_NAME as ...
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1answer
3k views

SQLSTATE[HY000]: General error: 1025 Error on rename of

I'm getting this error: SQLSTATE[HY000]: General error: 1025 Error on rename of './salt/ghost' to './salt/#sql2-4ab-630b' (errno: 152). Failing Query: "ALTER TABLE ghost DROP FOREIGN KEY ...
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2answers
2k views

Client to use the slave when the master is down in MySQL replication

Is it possible for the client to use the slave when the master is down in mysql replication? I have already setup a simple mysql replication having a master and a slave. The client connects to the ...
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1answer
593 views

Programatically testing slave status - What fields in SHOW SLAVE STATUS indicated slave status is OK / in ERROR?

We use pingdom and a few internal heartbeat mechanisms on our product. We would like to add a 'are our slaves running and in good shape' check. What fields in SHOW SLAVE STATUS indicate that the ...
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835 views

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2?

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2 ? updated to answer the 3 questions: mysql> show variables like 'version%'; ...
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mysql bin-log.index not found

I moved my bin-logs to a different folder: log-bin = /storage/mysql/bin-log log-bin-index = /storage/mysql/bin-log.index When I try to start mysqld I get this: /usr/libexec/mysqld: File ...
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1answer
948 views

I am getting an error while trying to download binary for mysql 5.5.11

I am trying to upgrade MySQL 5.1 to 5.5.11 on Ubuntu 10.10. Everytime I try the wget command I get this error: wget ...
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4answers
3k views

MySQL SSL disabled on Windows

I want to enable an SSL connection to my database. I've created SSL certificates and so on, however SSL remains disabled: mysql> show variables like '%ssl%'; ...
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2answers
797 views

Mysql master-master permission replication issue

I came to know it's safe to replicate mysql database to have the users and permissions replicated, from a post in ServerFault is-it-ok-to-replicate-mysql-db. I have setup master-master replication ...
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2answers
2k views

Join three tables

I have those three tables SELECT occuId as 'Occupation Id',occuDscr as 'Occupation Description' FROM occupation_field; +---------------+------------------------+ | Occupation Id | Occupation ...