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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1answer
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Query from database

I have a table named mip. The table has primary key id, a foreign key product_id and a column usage_type. product_id is a primary key id to a table named product. It is one to many relationship from ...
2
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1answer
87 views

Replicate from master-master setup

I have MySQL Master-Master replication on 2 servers. I want to replicate to another slave server. When I configure the slave to replicate from master1, only data added on master1 is replicated. ...
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1answer
2k views

How to protect mysql database from sql-injection?

I am new to databases and security. I am planning to put up a website. I've read that sql-injection vulnerabilities can be very dangerous since the server might leak user passwords and ...
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1answer
1k views

SQL set profiling

I'm setting up an automatic database backup for a website. When I try to do a backup it comes up with the error" MySQL error: The 'SHOW PROFILE' feature is disabled; you need MySQL built with ...
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2answers
32k views

How do I shrink the innodb file ibdata1 without dumping all databases?

InnoDB stores all tables in one big file ibdata1. After dropping a big table, the file is keeping its size no matter how big the table was. How can I shrink that file without having to dump and ...
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2answers
1k views

Choosing MyISAM over InnoDB for these project requirements; and long term options

Sorry for the long post, but I had to give as much info as possible to make this very vague question more specific. My project's aim is to let users search a (huge) database of variety of products. ...
5
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2answers
139 views

mysql join by 2 ways - how it works? - which gives performance difference

I had 2 different ways to query the content which showed performance difference when executed. The 1st way is EXPLAIN select SOME_COLUMNS from ( select * from A where CONDITION ) p inner join ( ...
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1answer
1k views

Does TRANSACTION/COMMIT/ROLLBACK only work on certain MySQL engines such as InnoDB?

Are transaction functions only relevant for particular database engines on MySQL, or are transactions supported under all MySQL engines, including MyISAM and InnoDB? someone says here that ...
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1answer
194 views

Does MySQL compress the stored data?

When I export a database in MySQL, it gives me a .sql file. Let's say this .sql file is 80 MB. Are they compressed in order to reduce disk space usage? Is that 80MB real physical-storage size?
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1answer
10k views

SELECT LIMIT 1 per column value?

Lets say I have the following table ----------------------------- | user_id | comment | ----------------------------- | 2 | thats cool | | 2 | awesome | | 3 | ...
4
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1answer
4k views

Is Percona xtrabackup the right choice for my 500GB MySQL backup?

I have a MySQL db with 500GB, consisting mainly of Innodb tables, and one big (200GB) MyISAM table. My current backup strategy is copying the db files to an external harddrive. This causes a downtime ...
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2answers
775 views

Count consecutive null rows from a joined table

I have the following tables: members: ---------------------------------------------- | member_id | member_name | member_join_date | ---------------------------------------------- events: ...
2
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1answer
2k views

shopping cart database schema

I need help creating the schema for a database to hold information relative to a web user's shopping cart/session. Each session will have a session ID, a time stamp holding time of creation, an expiry ...
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1answer
1k views

mysql show processlist hanging processes;

We needed to move services from one co-location patner to another so we had to copy some files from main server to back up server so these services can now be run on back up server at the new ...
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1answer
732 views

Setting up MySQL circular replication in existing replication topology?

I have the following MySQL replication topology set up for fault tolerance/disaster recovery with master server A and slaves B and C: A replicates to B A replicates to C Both B and C are fully up ...
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3answers
13k views

MySQL replication - slave is continuously lagging behind master

I am using MySQL-5.1.50 with a Master-slave replication setup. Most of the time the slave is lagging behind the master. When I run show processlist;, there is no query that's taking a long time. ...
5
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1answer
14k views

MySQL: Optimize UNION with “ORDER BY” in inner queries

I just set up a logging system which consists of multiple tables with the same layout. There is one table for each data source. For the log viewer, I want to UNION all the log tables, filter them ...
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2answers
3k views

MySQL / InnoDB: Does daily optimization improve performance?

Would performing daily optimizations of tables increase performance for MySQL and InnoDB? I have never did this before, but I have seen this module for Drupal http://drupal.org/project/db_maintenance, ...
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1answer
2k views

SQL Query - Set Date Variable by Table/Column Reference

How do I set the @DATE variable by using a table/column reference? Right now I've set it manually as you can see below with the opening: SET @DATE = '2012-03-31 01:00:00'; The table from which I ...
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2answers
2k views

Partitioning a table vs moving entries to another table

I don't understand how partitioning helps me more or less than using a separate table to store older records. I need to maintain a list of stock entries along with historical records about the stock. ...
3
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1answer
264 views

Economic Database Architecture Possibilities w/ Data of Varying Length

I'm in the process of designing a MySQL database (InnoDB) that holds a large amount of economic data which our application scores. The size of the economic data varies a great deal: some measures, ...
3
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1answer
125 views

Slow MySQL query, not sure why

I'm working with an intranet application for property tax collection, and I've hit a snag. The following view runs much slower than I'd expect: create or replace view propertytaxessub0 as select ...
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2answers
3k views

Mysql giving only 25 inserts per second

I'm using ubuntu 12.04 LTS Processor : Pentium(R) Dual-Core CPU E5200 @ 2.50GHz × 2 OS Type : 64-bit Memory : 3.9 GiB Disk : 101.1 GB I installed mysql and wanted to test insert performance. Here is ...
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2answers
450 views

mysqlslap number in sql statement to change with iteration

I am trying to figure out how to increment a number in a mysqlslap query with every iteratiom. Let me explain what I exactly mean: I got a query: SELECT age FROM member WHERE id = [some number] ...
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0answers
190 views

How can I force myisamchk to modify the original data file in case of duplicate keys?

In the documentation for myisamchk, it says: --quick, -q Achieve a faster repair by modifying only the index file, not the data file. You can specify this option twice to force myisamchk to ...
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1answer
870 views

MySQL slow sending data

I have a large table that frequently sends 3,000 rows of data to a client. The longest wait state is Sending data. I would like to minimize this if possible! Is there a foolproof way of doing so? ...
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1answer
1k views

MySQL Master-Slave Replication Cross Database

I am setting up Replication for cross Database as i have set 2 variables in Slave' s my.cnf as replicate-do-db=database_name and Replicate-wild-do-table=database_name.% ,But i am not able to get ...
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1answer
3k views

MySQL 5.5 Runs Out of Memory, Drops All Connections When Creating Many Databases

I'm running into a problem when I create a large number of databases consecutively on an Amazon RDS db.m1.large instance. The MySQL Engine Version is 5.5.23. At some point, the RDS instance drops all ...
5
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1answer
8k views

Product Attribute List Design Pattern

I am working on updating our website's product database. It’s built in MySQL but this is more of a general database design pattern question. I’m planning on switching to a Supertype/Subtype pattern. ...
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1answer
664 views

Stored procedure arguments get immediately truncated

I have a stored procedure with a single SELECT statement inside: DROP PROCEDURE `pos_neg_test`// CREATE PROCEDURE `pos_neg_test`(IN start_ts TIMESTAMP, IN end_ts TIMESTAMP) BEGIN SELECT ...
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1answer
519 views

What is the underlying representation of BLOB data when I export it?

When I export a blob object to an SQL file, I get some thing like this for a blob field: 0x4f3a383a227374644....., Questions I would like to know how the BLOB is actually converted to the above ...
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1answer
1k views

High MySQL CPU usage, queries seem fine, not running ntp

I've had about 48 hours of extremely high CPU usage on my main MySQL database for no apparent reason. I realize this question is quite similar to the one posed here: High CPU usage from MySQL with no ...
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1answer
197 views

Are these custom module Drupal tables lacking foreign keys? mysqldump with table structures without data is included

I am troubleshooting a some tables in MySQL used by a custom Drupal module. Documentation for these tables is poor so I used mysqldump to get the structures in the Drupal database without the data. I ...
5
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1answer
6k views

MySQL: Illegal mix of collations

I've tried using a stored procedure to create indices, and got the following error: ERROR 1267 (HY000): Illegal mix of collations (utf8_general_ci,IMPLICIT) and ...
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3answers
547 views

Mysql error while creating FK

here is structure of both tables category table CREATE TABLE category ( `catID` bigint(20) NOT NULL AUTO_INCREMENT, `title` varchar(60) NOT NULL, `created_at` timestamp NOT NULL DEFAULT ...
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1answer
468 views

Combining a tree structured Group model with its HABTM User model in one VIEW

I have a tree structured model Group which has the columns id, parent_id, name, lft and rght. I also have a model User which has the columns id, name and password. Group and User have a ...
2
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1answer
1k views

Find which numbers in [1, 161] are not in the result set?

How to find which two number in [1, 161] is not in the result set? Can I find this two numbers using sql command? mysql> select blog_id from wp_blogs; ... | 149 | | 150 | | 151 | | ...
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1answer
4k views

Print table documentation with comments?

I have a MySQL database, and I have used MySQL Workbench to insert text into the "comment" fields of many of the columns and tables; the plan was to have the documentation stored in the database. ...
2
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1answer
307 views

How do I switch master with slave and vice versa on MySQL?

I have two instances of MySQL, one master and one slave. How can I switch them to make the slave the master and vice-versa while avoiding downtime?
2
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1answer
5k views

execute() vs executeQuery() in MySQL Connector C++

With MySQL Connector C++, I can use the sql::Statement::execute() function if I am going to modify the database (INSERT, UPDATE, DELETE, MERGE), or the sql::Statement::executeQuery() function if I am ...
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1answer
163 views

Is MySQL replication suitable for a Write Mostly application?

I'm considering adding another server to my one-server setup application with 600GB MySQL DB. The db and the apache are both running from the same server. In order to avoid backup downtime and improve ...
5
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1answer
861 views

MySQL database normalization 3NF

I have homework where I need to create simple web interface and a DB normalized to 3NF. I've chosen ISP client selfcare as my database purpose. Web interface is no problem, the normalized DB is. After ...
21
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2answers
27k views

MySQL: Create index If not exists

Is there a way to create an index in MySQL if it does not exist? MySQL does not support the obvious format: CREATE INDEX IF NOT EXISTS index_name ON table(column) ERROR 1064 (42000): You have an ...
2
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2answers
731 views

mysql myisamchk vs mysqlcheck

We have a mysql database running version 5.0. Every month we shutdown the database for maintenance. We run a myisamchk on the tables to fix data fragmentation, and this takes down the system for up to ...
2
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1answer
150 views

MySQL full text search result problem

I have this query that does not return any results: SELECT MATCH (e.firstname, e.lastname, e.tc_identity) AGAINST ('Baha') AS Score , e.* FROM employees AS e WHERE MATCH (e.firstname, ...
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1answer
2k views

Create second instance of mysqld on windows xp

I am trying to install the new version of the mysql on the windows7 and windows xp . In few of the computers already a new version of mysql are installed. Here I just want to create a second instance ...
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1answer
3k views

My master to slave replication stopped and is showing this error when I use SHOW SLAVE STATUS;

My master to slave replication stopped and is showing this error when I use SHOW SLAVE STATUS; | Waiting for master to send event | 172.16.10.37 | repl | 3306 | 60 | mysql-bin.000256 | ...
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1answer
70 views

Give privilege to new created databases in MySQL

I have user "U" who I want to give him full access to all the existing databases except "db1". I want him to only have select privilege for that db. What I did is I gave "U" all permissions for each ...
5
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1answer
6k views

How do I reduce the database size on AWS RDS MySQL?

I have an RDS MySQL database on Amazon Web Services. I want to reduce the size of the database in the control panel in order to save money. Q: How do I make it smaller? Their site says you have to ...
5
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1answer
3k views

How are multiple indexes used in a query by MySQL?

Imagine a table where there are separate indexes on columns a and b. The query runs somewhat like this: SELECT col1, col2 FROM <table> WHERE a = 'value_1 AND b = 'value_2'; Now, does this ...