MySQL : Open-Source, Relational Database Management System

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MySQL Replication with Tungsten

I am trying to setup a multi-master type of replication with each master having an additional slave using tungsten. As an example, lets say I have 4 hosts (A,B,C,D) and Hosts A and C are the Masters, ...
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40 views

Amazon RDS mysqbinlog “Could not find first log file name in binary log index file”

Preamble: We use RDS at AWS to manage our MySQL database. I know that RDS creates binary logs used for replication.. I want to harvest these binary logs and store them on S3, so that at any time, i ...
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Get categorie, subcategories and number of products assigned to each

I have a list of products, and a list of categories, and a join table. Products can be assigned to multiple categories. Categories can have one level of subcategories. The tables look something like ...
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41 views

update variable from multiple tables in one row

I have two databases, and I need to UPDATE variable 'birthday' from one row to another checking 'name' (from db1 to db2). The problem is, that 'name' variable in second db is located in another table ...
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1answer
35 views

Will MySQL be effective when selecting a row from a table with billions of records?

Note: this is a hypothetical scenario Lets say that: I'm running MySQL, InnoDB engine, UTF-8 encoding I have a table with 50+ billions of rows The tables primary key is a BIGINT The table also has ...
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23 views

Mysql will not start

Please help, I really need to recover my databases. service mysql start start: Job failed to start mysqld --verbose 140401 20:16:11 [Warning] Can't create test file ...
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82 views

What are the disadvantages of PostgreSQL compared to other DBMS? [closed]

I am a student studying PostgreSQL. I want to know the advantages and disadvantages of PostgreSQL in comparison to other DBMS.
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34 views

MySQL: LEFT OUTER JOIN within reason

What I'm attempting to do is LEFT OUTER JOIN a table, but I only want the last inserted record of the joined table to affect the results. Currently each table row within the joined table seems to be ...
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26 views

Using non-replicated read/write databases on a MySQL slave server

I have a MySQL slave server that has two databases being replicated from a master. What I'd like to do is add a third database that I will exclude from replication and use as a read/write database. ...
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41 views

MySQL Master <=(Slave,Master)=> Slave configuration

Sorry for the wonky title if it got you confused. I want to know if a server can be a slave and master at the same time. Our problem is that we have lots of mobile units that need to be synced to the ...
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31 views

Efficient way to fetch/update X records in a loop

What I need is a simple process that handles requests. I have setup a simple table as follows: CREATE TABLE Requests ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, request_param VARCHAR(250) ...
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66 views

Delete Query takes a long time

I have a innodb table that counts circa 1 billion entries. I started a delete operation (with a small where condition on an indexed column) that should delete a lot entries, leaving circa 100 million. ...
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MySQL import gets slower and slower until it virtually grinds to a halt, what can I do to maintain constant speeds?

I'm importing a large set of sql data into a MySQL (MariaDB 5.5) database, the files are from 200mb to 3g. I'm importing it one after the other, and it starts importing at speeds around 1MiB/s to ...
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24 views

How to update Status using IF Condition in Mysql trigger

I'm trying to write an update trigger that will Design_Update_Status to Customized when a date is entered in Custom_Design_Update_Date field and if nothing is entered that field it should update ...
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1answer
32 views

Index to fix this query MySQL

We have an extremely large forum running lots of third party software (Most of which doesn't run all that well) and we're starting to optimize things as time allows. This query keeps popping up in the ...
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49 views

Rollback parent procedure on failure in MySQL

I have the following two procedures on my server: CREATE DEFINER=`someone`@`localhost` PROCEDURE `NewMagnet`( IN `nick` VARCHAR(32), IN `tth` CHAR(39), IN `name` TINYTEXT, IN ...
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26 views

Need help with data model

Schema does not list all fields, but only the relevant ones User adds credits/funds to his account using paypal or Internet Banking (which has to be verified manually, and approved, so the 'status' ...
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2answers
51 views

How to Log All mysql queries into log file?

I am using Mysql 5.6.12 under Wamp server environment. Now I want to log All queries into ".log" file, the queries which are running by PHP or from PHPMyAdmin, I want to log them...
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20 views

Which tool to use to generate an ER Diagram that will allow navigation between tables

DB= Mysql 5.X , OSX/Windows I have a DB with over 400 tables. I want to use a tool to reverse engineer the db to an ER diagram that will allow me to navigate between tables. So for example, when I'm ...
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1answer
12 views

Create table shows ERROR 1005(HY000) errno 150

i tried to create tables as per given in my textbook in MySQL server as follows: create table department (dept_name varchar(20), building varchar(15), budget numeric(12,2), ...
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38 views

mysql directory grow to 246G after one query, which failed due to table is full

I was trying to run the following statement with the hope to create a join of two existing tables. create table CRS_PAIR select concat_ws(',', a.TESTING_ID, b.TRAINING_ID, a.TESTING_C) as k, ...
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28 views

Every 30 minutes mysql stuck for 20-30 seconds [closed]

I have very strong mysql 5.5 computer (Windows server / AWS) . My CPU ~8% ,Disk IO - 0.5% , ~Connection - 800 binlog_format=MIXED, innodb_read_io_threads=64, innodb_write_io_threads=64, ...
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30 views

MySQL database freezing after 'use'

I recently made a rather stupid mistake and corrupt my Ubuntu installation. To resolve it, I booted with a live cd and copied the database files over. However, now I have copied the folders from the ...
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61 views

How to make a better Data model

I am creating a database system using MySQL for a group in my school (a University). I am new to MySQL and its usage.I have started with the data modelling process, since this process will be the main ...
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Converting UUID's from CHAR(32) to BIN(16)

I have a few questions relating to UUID's, but before I go on, let me explain our schema a bit, first, we're on MySQL 5.5 (Percona's version to be exact)... In each applicable table, we use a two ...
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59 views

UPDATE CONCAT without duplicates

I would like to concatenate multiple values ​​and remove duplicates (case-insensitive) in the same field with SQL only. Without using a unique key or stored procedure. Ex. ...
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MySQL/MariaDB CLI limits max password?

I've got strange problem - my MariaDB instance CLI (Linux) does enforce limit on how long password can be. For example, setting password like this UPDATE mysql.user SET ...
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1answer
24 views

MySQL Query Cache - what type of queue is used?

I am wondering what type of queue is MySQL Query Cache using. When there is new query and cache is full which query is deleted? Oldest one? One with fewer number of hits? Or maybe there is some ...
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10 views

specify database while executing mysql binlog

We have different mysql servers with same database names, is it possible to restore their binlogs into one server (different database names) ?
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28 views

How Many Nodes For MySQL Cluster Setup?

I quit not fully understand how exactly MySQL Cluster does to bring faster queries and faster databases operations. I have 1 MGM cluster (management cluster) 1 MySQL API cluser (mysqld) 2 ...
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1answer
35 views

ALTER TABLE - Rename a column

This got me nuts! I want to rename a column from read-more to read_more in blog table Tried all this: ALTER TABLE blog RENAME COLUMN read-more to read_more; ALTER TABLE blog CHANGE COLUMN ...
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1answer
38 views

Is there any way to get the estimate cost of executing a query in MySQL?

In PostgreSQL, EXPLAIN or EXPLAIN ANALYZE will show the estimate cost of executing a query. But EXPLAIN in MySQL doesn't provide this information. How can I get the estimate cost without installation ...
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43 views

MySQL not releasing memory

MySQL seems to want to keep an entire table in cache (table size = ~20GB) after any large inserts or select statements are performed on it. Right now my innodb buffer pool is 20GB. Total RAM is 32GB. ...
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MySQL query optimization for legacy application

I'm working with a legacy application that started out with little data years ago (developed by a third party custom for this client), and now we're seeing MySQL load skyrocket on this query alone. ...
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MySQL 5.1 replication broken after crash, duplicate key error, why? No redo log corruption

What do you think is the reason for the duplicated key errors in our MySQL 5.1.61 replication slave, after the slave machine crashed? It's not corrupted redo logs. Details follows: We have ...
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MySQL error 1241 operand should contain 1 column

I'm trying to write the following query, which gives me error 1241 saying operand should contain only 1 column: SELECT mobobj.description AS Description, mobID AS ID, location.description AS Location ...
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mysqldump: dump several tables from db. what will be locked?

I have active database with dozens of tables. Among them several are unused (no queries/insertions are performing over them for a while). I want to dump that inactive tables. I would suggest that it ...
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28 views

Alphanumeric field in MySQL

I need to create a character field with some rules, they are, Field name: contract_number. Rules: Contract Number Contract number must be alphanumeric. Contract number must be unique. Contract ...
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How to Replicate data from read only sql database to Active one

We are applying logs in every 30 min to one SQL db which has to be in Restoration Mode/Read only mode as we are applying logs continuously. Now we have to Set up Replicaion of this Read only Db to ...
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How to update top 10 rows in all Departments

i Have A 109 of Industry's and Date Wise JobPosts in job_post Table like Table: Job_post Field1: jobpost_id Field2: jobpost_date Field3: jobpost_Industry *How i Update Every Industry's top ...
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When installing mysql in linux, why do we create a mysql group and user?

When installing mysql in linux, why do we create a mysql group and user ? The installation step tells to create a user and to change the ownership of mysql folder to mysql.
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Import data from a CSV file without creating a table first in MySQL

I want to import CSV data into mysql database. Additionally, I dont want to create a table first and then import. That means, if my csv file name is test.csv, and its contents are like ...
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161 views

Why does InnoDB table by default uses the UNIQUE constraint instead of the PRIMARY KEY?

In my MySQL database I have a table with 4 columns, the PRIMRAY KEY, two columns with a FOREIGN KEY CONSTRAINT and one UNIQUE index on all fields except for the PRIMARY KEY. The SHOW CREATE TABLE: ...
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How to make make my query run fast?

How to make this query run faster? Table contains over 2 million rows of data and takes around 30 to 120 seconds to process the query. SELECT INET_NTOA(blocks.startIpNum), ...
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2answers
198 views

Optimized query to fetch a record from 10 million entries

A table has 2 fields | UniqueKey | TimeStamp | ------------------------- | xfsddddq | 1024125412 | | xfstttdx | 1024125413 |< | xfsdxxau | 1024125415 | Estimated, there are 10 million ...
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How can I create a view in a stored procedure on MySQL?

I am trying to dynamically create views based on an SQL query and have a trigger recreate them when the fields in the view are to change. When I call the procedure I end up with a permission denied ...
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When tables are locked does MySQL queue queries?

I have a small production website, but it's live 24/7. When running the Optimize, Analyze or Repair commands, MySQL locks the table it is working on. QUESTIONS How would this effect users trying ...
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mysqlcheck -o --all-databases does not finish

I have a problem with my MySQL Databaseserver. I have many tables and there is quite some traffic going on there (around 4 connections per second). Since the phpMyAdmin advised me to do a OPTIMIZE ...
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How to delete list of email addresses from MySQL database?

I have a list of invalid email addresses parsed in the following format; There are roughly 1500 invalid addresses, and I need to remove them from my myBB users. What SQL query can I run to remove ...
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MySQL setup - different users for different programs using the database?

I'm setting up a MySQL DMBS for my webserver & CraftBukkit servers that are hosted on the same computer. The Bukkit servers have several plugins that will be accessing specific tables on the ...