MySQL : Open-Source, Relational Database Management System

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Sensible data management tool for importing and exporting of large data files

I am looking for some sensible suggestions on data management tools for large data files. I have been experimenting aith excel and access only to find that access has limitations on import files size ...
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2answers
3k views

“freeing items” taking forever on inserts, updates and deletes

Recently I migrated all my MySQL database tables from MyISAM engine to InnoDB. I'm using the DotCloud MySQL service as my server (http://docs.dotcloud.com/services/mysql/). After the migration, ...
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1answer
309 views

Replication and REPAIR TABLE

When running a repair table on a corrupted or damaged table, will this guarantee replication to break? Documentation says "in the event that a table on the master becomes damaged and you use REPAIR ...
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1answer
201 views

what are the checklist when looking at MySQL database for first time?

What should I put on my checklist when I look at MySQL database for the first time? I would appreciate your help. Thanks.
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1answer
401 views

How to propagate a grandparent relationship throughout a tree?

I've got a MySQL table with columns id and parent, wherein each row has another row as a parent, except for some special root rows with parent=0. There are no cycles or broken relations. In order to ...
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3answers
2k views

Speed up search across multiple columns

We have a table: user_info (user_id,domain_id,first_name,middle_name,last_name,work_place,.,.,.) Now, we have a user search that search across three columns first_name,last_name and work_place. ...
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2answers
237 views

Is there a reason/benefit I am not aware of for this kind setup?

I now manage a MySQL database that was designed and created by another. I am confused about a certain setup that the original developer created.. He did not use auto increments for table IDs. ...
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2answers
11k views

Using multiple cores for single MySQL queries on Debian

I am running a MySQL server for tests on a VM (VMWare) with Debian as guest OS. The guest has four emulated CPU cores, so I set thread_concurrency to four. I am doing expensive joins on large tables, ...
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11answers
12k views

Why aren't primary key / foreign key matches used for joins?

As far as I could find out many DBMSs (e.g. mysql, postgres, mssql) use fk and pk combinations only to constrain changes to data, but they are rarely natively used to automatically select columns to ...
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1answer
1k views

how to use “mysqld -O thread_stack=#”

I keep getting this error whether I run my query from the terminal or from within Java. Anyone has some instructions how to resolve this? Thread stack overrun: 5768 bytes used of a 131072 byte ...
2
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1answer
353 views

Why is mysqlhotcopy slower compared to rsync?

My understanding is mysqlhotcopy works very similar to rsync. In one of our servers backing the database file using rsync takes about 15 minutes for 50GB data. Backing up the same data using ...
2
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1answer
896 views

Correct SQL Server linked server connection settings to MySQL that will allow inserts

I'm in linked server hell! I've created a linked server to a remote MySQL database. I'm able to query and do updates. However when I attempt an insert I get an error: "[MySQL][ODBC 5.1 ...
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2answers
1k views

Is my EER Diagram correct? Why use relationships?

This is the first time I've made an Entity Relationship Diagram (ERD) for MySQL. Prior to this, I would never create relationships between tables, I would simply create the tables in MySQLAdmin and ...
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2answers
13k views

Why do MySQL tables crash? How do I prevent it?

I'm the Administrator of a Moodle site which had its Users table corrupted and it became unusable. Luckily, a simple REPAIR TABLE mdl_user made it work back again. The thing is that I don't know why ...
2
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1answer
663 views

Dual management node for mysql clustering

I currently have mysql cluster setup and running. Here is my current setup: 1 - management node 2 - data nodes 2 - mysql nodes I wish to incorporate a failover for the management node. The ...
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2answers
912 views

How can I check if the keys are enabled on a MyISAM table?

I have a script, which populates 4 tables. It goes like this: Disable the keys on all the tables Populate the tables Enabled the keys back. The problem is that windows decided to reboot the ...
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1answer
1k views

Problem with Error: InnoDB: page … log sequence … number is in the future!

i know this question was asked before, but i am at a point where i am really stuck and do not know how to continue with this problem and i would really like to know, what causes this error to come up. ...
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4answers
4k views

Creating Archiving database for old data in MySQL

I Have a Master and Various Slave Servers. There is a huge amount of the data on all the servers and I wish to create an Archiving system for our Data. Scenario is : I want that only Last one year ...
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2answers
2k views

Data Base Administration Oracle vs MySql? [closed]

I have worked with MSSQL for a while now, but now we want to try to move to some open source for a specific part of the company's products or explore Oracle if possible. What would you say are the ...
2
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1answer
316 views

optimal table design mysql with primay key and varchar value

I have a table: id (PRIMARY KEY AUTO_INCREMENT) value (UNIQUE KEY) which currently holds over 50 millions rows (and growing fast) and is hit hard: process 1 queries this table (>200/sec) with a ...
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2answers
12k views

MySql recommended hardware

Our company servers are currently hosted on a VPS and we've decided to move into dedicated servers. When choosing the best hardware for a DB server, what should we invest more resources: better CPU ...
2
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1answer
2k views

Can I mysqldump an entire database while using where='condition' on individual tables?

I have used mysqldump to dump an entire database, However, when I want to use --where=condition", on individual tables, I have dumped individual tables mysqldump --where='condition' mydb table ...
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1answer
218 views

MySQL row length is almost the triple of what I expect

I shamelessly took title and content from this question and adapted it to my similar yet different problem: This is the table I have: CREATE TABLE `test` ( `field1` MEDIUMINT(8) UNSIGNED NOT ...
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3answers
15k views

How to initiate MySQL on Mac OS X 10.6.8?

I followed this tutorial to install MySQL on Mac OS X 10.6.8. Now I get he following errors: $ mysqladmin version /usr/local/mysql/bin/mysqladmin: connect to server at 'localhost' failed error: ...
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1answer
917 views

How to set datadir to different values based on the hostname in my.cnf?

How to set datadir to different values based on the hostname in my.cnf? I want to use the same my.cnf file on a Linux machine and a Mac OS X machine where the datadir should have different values.
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573 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
1k views

How do you structure a database that allows for groups to be formed/added by users and also be a part of like facebook?

I'm new to databases and web development so a laymen explanation is best for the time being. I'm only in the data modeling phase so no need for specific code. I'm just trying to wrap my head around ...
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1answer
320 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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3answers
1k views

How do you structure a database that organizes post by location like craigslist?

I'm new to databases and web development so I'm just looking for a laymen explanation. No need for specific code, just theory. I understand OneToMany and ManyToMany relationships, so no need to ...
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3answers
621 views

Just how much is a query supposed to slow down the whole system?

This is similar to my earlier question but more generic. I have a system with 16GB of memory, 16 cores, supposedly quality hard drives, RHEL 5, MySQL 5.0.x. Yes, I know, we're working on upgrading ...
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1answer
119 views

How to determine if a column is the first part of an index?

Is there anyway to tell with SQL if an indexed column is the first part of an index. The closest thing looks to be information_schema.columns. But that seems to only tell me if it's a PRI or MUL key ...
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1answer
5k views

How to set a specific directory location for individual MySQL database?

Is it possible to set each database in MySQL to use a separate datadir? I'm running a userdir development (sandbox) server and would like to put the MySQL data files for the database(s) for that user ...
3
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1answer
1k views

MySQL ignoring index, index cardinality is the same as number of records in the table (?!)

Everyone, I could use an extra set of eyes on an issue we've come across. Here's what we're seeing: We're writing some code to migrate our messages to a new table called communications. We're ...
5
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1answer
1k views

Preventing replication of alter table command to change engine

I am in the process of switching a MySQL table from MyISAM to InnoDB and I do not want the slave to perform the alter table command until I execute it manually. The intention is to have a backup for a ...
4
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2answers
937 views

Read mysql config (my.cnf) using mysql console

I have a mysql server that is not under my control (I don't have ssh on that machine). I only have access to one database using mysql client. How can I have access to config options that are declared ...
4
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2answers
6k views

Performance settings for MyISAM tables - keep everything in memory

I have a 8-core MySQL server with 32 GB of RAM, holding 40 MyISAM tables (total: ~4GB of data). Since the databases size is several times smaller than the available memory, how can I make full usage ...
3
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3answers
3k views

Finding five-minute interval prior to current time

I want to find the five minute interval just before the current time. So if the current time is 8:43 I want to return 8:35 and 8:40. Here is the query that I have written and it is working as ...
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0answers
8k views

Alternative OpenSource/free to MySQL Cluster Manager Client? [closed]

I need to deploy a MySQL cluster but initially no bucks for the MySQL Cluster Manager Client. It's at least $5k and I actually think in my case it will go way over that. I looked a lot on Google (a ...
2
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1answer
2k views

Best way to compare strings using pre-built ngrams?

I'm struggling with an n-gram problem and have been hunting the Web for examples to help me out and have noticed n-grams being discussed on this forum. I'm working on a system where we've got scraped ...
3
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1answer
515 views

How do I prevent updates on an entire table (but allow inserts) in Mysql 5.5?

I want to make the rows in a Mysql table immutable, once they are inserted I don't want it to be possible to change them. How can I do this? This question handles making individual rows immutable, ...
4
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2answers
7k views

Can mysql restore a single table from a large mysqldump?

What is the best way to restore a single table from a large (~5GB) database mysqldump file? update: I have found solutions (posted below) using command line tools to parse the table, but is there a ...
3
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1answer
228 views

MySQL chain replication

I have 3 servers A, B and C. What I want to do is replicate databases like this A->B->C, where A is replicating DB1 and DB2 to B and B is replicating those same databases to C, but I would also like ...
4
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1answer
421 views

index not being used

I have an exact same myisam table on master and slave. The indexes are not being used on Master server. mysql> explain select count(date_time) from ox_data_summary_ad_hourly where date_time = ...
2
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1answer
96 views

Linking identifiers across tables in MySQL (Foreign Keys)

Given a simplified example of two tables table Contact(ID int primary key, Name text not null) table ContactPhone(ContactID int not null, PhoneNumber text not null) Is there a way to tell MySQL ...
3
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3answers
106 views

A join aggregate behaviour I can't understand

Query 1: SELECT c.class_id, SUM ( CASE WHEN s.student_id IS NULL THEN 0 ELSE 1 END ) as total_students FROM classes c LEFT JOIN students s ...
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2answers
658 views

What is this host?

I found this in my local MySQL installation today: mysql> select host, user from user; +--------------+---------+ | host | user | +--------------+---------+ | ::1 | root | | ...
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2answers
289 views

What does Threads_connected=-1 signify in MySQL?

I was running the following: mysqladmin -u root -p ext -ri 10 | grep Threads_connected and was kind of surprised to find that Threads_connected could be -1: | Threads_connected | 1 ...
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1answer
154 views

What are some key configuration settings for using an InnoDb table for session storage?

I want to start clustering my PHP app servers but don't want to go for a sticky-sessions load balancing setup at this point. However, I want sessions that are persisted to disk and implement proper ...
3
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1answer
960 views

Keeping MySQL staging database on same server updated from production

I just migrated my MySQL 5.5.20 to Amazon RDS from MySQL on EC2. The one thing I'm having difficulty with is how to keep my staging database updated from production. Before, I just ran a nightly ...
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1answer
286 views

MySQL replication risks for the master

I have a production MySQL server, fairly heavily loaded with an INSERT-only load on one of its databases. I'd like to attach a non-production (sitting on my desk, more or less) replication slave to ...