Questions tagged [mysql]

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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MySQL - MySqlDump uses \n instead of null

Using Windows with MySQL 5.1. I am running a script that uses mysqldump to backup a database. The mysqldump syntax used is: mysqldump --user=root --port=3306 --password=topsecret some_database --...
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2answers
538 views

MySQL: Slow log; append CPU usage

I have the MySQL slow log feature enabled: http://dev.mysql.com/doc/refman/5.1/en/slow-query-log.html But sometimes the query_times are high simply due to high CPU load. How can I append the current ...
5
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2answers
3k views

How to optimize the my.cnf of a MySQL server that mixes InnoDB and MyISAM tablespaces?

I have a database that, because of some issues, I needed to convert some tables from MyISAM to InnoDB. I basically did this: set sql_log_bin = 0; set sql_mode = 'STRICT_ALL_TABLES'; ALTER TABLE `...
0
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1answer
529 views

Why mysqld server service gets aborted when i start mysql client service? [closed]

I am installing mysql-5.5.7rc from source code. After installation when i start mysqld service is being run but as soon as i run mysql client service server service gets aborted.. And also ...
2
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3answers
9k views

How to detect a running mysqldump?

Here are the things I can't change: We got a mySQL myISAM replication running a master and some slaves. One slave is being used for nightly backups using mysqldump. The backups is using heavy locks ...
6
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2answers
9k views

What is the right time to use an ENUM versus a normalized types table in MySQL? [duplicate]

Possible Duplicate: Advantages and Disadvantages to using ENUM vs Integer types? Considering MySQL only... I'm curious to know what the community thinks the proper use-case for an ENUM type vs. ...
2
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1answer
2k views

Mysql Impossible WHERE and enum

I'm using enum as an alternative to check constraint which is still not supported by mysql. Could you clarify why optimizer doesn't take into account allowed values for enum ? For example, CREATE ...
9
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1answer
36k views

Client times out, while MySQL query remains running?

We experienced an issue in which a read-only query, run through MySQL workbench, timed out from a user's UI perspective and remained running on the server (and apparently consuming more and more ...
1
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1answer
1k views

MySQL not reading my.cnf in MAMP

Running MAMP (not PRO) 2.0.5, MySQL 5.5.9, locally on OS X and I cannot get MySQL to read a my.cnf file. I've tried throwing it in the following directories with no results: /Applications/MAMP/conf ...
5
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1answer
10k views

Query performance with subquery and IN clause

I am trying to select a range of data for multiple devices (unique serial numbers) from a historical table and was wondering why there is such a big difference in time for the following queries: ...
5
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1answer
562 views

Tools for cnf management, generation? [closed]

Does anyone know of any good tools for cnf configuration management? It's often the case I have a group of machines that has a very similar config except for a few differences such as server id or ...
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2answers
660 views

Moving MySQL database from UniServer to Ubuntu Server?

I have set up Ubuntu Server 11.10, and plan to host my website on it. Until this point I was using UniServer to host it in a portable fashion. Using the built in MySQL. This is fine, and through ...
2
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1answer
7k views

16 Cores 12 GB RAM server MySql Configuration - my.cnf

The server takes 20+ seconds (wait time/slow IO response time) to response to a HTTP request even with memcached and APC installed. I believe this has something to do with MYSQL since the site as lots ...
2
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1answer
373 views

MySQL Trigger problem with the email address (cause contains the @ sign)

I'm trying to set a trigger in a table (users) to "copy" the email address of a new row to another table (prova). Here is the trigger: CREATE TRIGGER inserisciemail AFTER INSERT ON users FOR EACH ROW ...
5
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5answers
14k views

MySQL said “InnoDB: Initializing buffer pool, size = 128.0M”, does it mean it is using 128MB RAM?

I am just using a very few InnoDB tables (e.g. less than 1MB), but during MySQL startup, it said InnoDB: Initializing buffer pool, size = 128.0M Does it mean even I am using in such a small size, ...
1
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1answer
238 views

MySQL detect duplicate human names [closed]

I've been tasked with identifying a solution to help identify possible duplicates when inserting new user records into a MySQL database. Does anyone know of any cheap, preferably free, solutions? The ...
3
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1answer
24k views

Multiple left joins or subquery?

I'm working on joining multiple tables together to extract some data related to user "runs", this includes basics like runID, username etc but also joins to the run times and favourites. I have the ...
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2answers
3k views

Join three tables

I have those three tables SELECT occuId as 'Occupation Id',occuDscr as 'Occupation Description' FROM occupation_field; +---------------+------------------------+ | Occupation Id | Occupation ...
7
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2answers
8k views

How to convert control characters in MySQL from latin1 to UTF-8?

While converting a database to UTF-8 I noticed a strange behavior regarding the control characters 0x80-0x9F. For example, 0x92 (right apostrophe) would not get converted to UTF-8 and truncate the ...
3
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1answer
2k views

Calculate percentage of false records to total records within a aggregate function

I'm looking for a solution to calculate a percentage rate of a boolean value: Model: Products 1 <-> n Components Components.essential is a boolean attribute What I want to calculate ...
11
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2answers
6k views

Any gotchas at all with converting from MyISAM to InnoDB?

I'm ready to move from MyISAM to InnoDB but wanted to know if there was a full list of things to look for? For example, I haven't seen any list mention that running DISABLE KEYS on an InnoDB table ...
1
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1answer
333 views

Conditional one to many queries in mysql

I have a simple patients table and lots of Lab tests table. Every patient can have many Lab tests. What i want to do is to only query the tests which are already entered for that specific patient and ...
9
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3answers
18k views

Storing time with milliseconds in database

Just a quick question regarding storing "time" in a database. I'm logging the time of users runs which are in the format 00:00:00:00 (hours, minutes, seconds, milliseconds). I was originally going to ...
2
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1answer
4k views

Write lock during mysqldump even using --lock-tables=false

When I try to dump an online database using --lock-tables=false, others cannot update the table. Are there any methods to solve this? As I am using MyISAM, does --single-transaction for InnoDB help? ...
4
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1answer
7k views

Rows with a variable number of columns?

I'm trying to design a database for a program that is storing and manipulating tweets off of Twitter. I'm using code to fragment a tweet into words, usernames, and hashtags, so I'm meeting @...
7
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3answers
11k views

Concurrent MySQL updates hang with InnoDB (on Amazon RDS)

I'm running into a problem where multiple MySQL updates being performed at the same time will lock up and takes several minutes to finish. I'm using InnoDB, so I'm confused as to why this could be ...
3
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2answers
8k views

“on duplicate key update” all the non-key fields mentioned in the insert

How can I update the field values mentioned in the insert portion without listing them again in the on duplicate key update portion? insert into tablename set keyname = 'keyvalue', fieldname = '...
4
votes
1answer
12k views

How to enable MySQL general log?

I would like to enable the MySQL General Log to view all the (slow) queries. I'm using XAMPP as server and have no idea how to enable it. I can't find a good guide on the internet. Can someone help ...
2
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1answer
352 views

Has anyone ran into this replication breaking bug before?

I've been having this issue where replication was breaking on colliding primary keys. The annoying thing was these were auto increment generated. I think my issues been tracked down to http://bugs....
1
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1answer
358 views

Is there any way to increase the mysql reserved pool for super users beyond 1?

http://dev.mysql.com/doc/refman/5.5/en/too-many-connections.html States that there is 1 connection beyond your maximum number of connections for users with the super privilege. My question is can ...
3
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2answers
3k views

Syntax to not write single statement to binlog?

I know you can SET SQL_LOG_BIN=0; to disable writing your session to the binlogs. I was wondering if there was some single serving query syntax to prevent just that one query from being written w/o ...
1
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1answer
126 views

keeping database columns consistent with documentation

For a project, the client wanted to be able to add fields to any item and have them be searchable. To make them searchable, that would require the fields to take a column, but that would make the ...
4
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2answers
5k views

MySql - How can I speed up this query

I have the following tables: CREATE TABLE `users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `first_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `last_name` varchar(255) COLLATE ...
2
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1answer
378 views

What's wrong with this update RANK query?

It was updated only the first time I ran it, after that the users_tbl_rank stays the same. $sql = "SET @r = 0; UPDATE users SET users_tbl_rank = @r := (@r + 1) ORDER BY users_tbl_points DESC"; In my ...
0
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1answer
503 views

which DBMS should i go for? [closed]

I am interested in learning a DBMS. As a beginner which DBMS should i go for ? I know few DBMS by name like Oracle,Sql Server,My Sql . How are these DBMS different from each other ? As a beginner ...
33
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5answers
34k views

How should I design a relationship table for friendship?

If A is a friend of B, then should I store both values AB and BA, or one is enough? What are the advantages and disadvantages of both methods. Here is my observation: If I keep both then I have to ...
4
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2answers
3k views

Errors after installing mysql

After installing mysql I get the following errors: > 120105 6:02:49 [Warning] Setting lower_case_table_names=2 because > file system for /usr/local/var/mysql/ is case insensitive mysqld: > ...
1
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1answer
98 views

Basic sql query problem [closed]

Here is the scenario: lets say I have a database named sqlprac that contains a table named dept. There are two ways to write a query: use sqlprac /*1*/ SELECT dept.deptno, dept.deptname, ...
5
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2answers
28k views

MySQL Replication Error

I am getting an Error on Slave as: could not execute Write_rows event on table mydatabasename.atable; Duplicate entry '174465' for key 'PRIMARY', Error_code: 1062; handler error ...
4
votes
1answer
2k views

How to UPDATE just one record in DB2?

In DB2, I need to do a SELECT FROM UPDATE, to put an update + select in a single transaction. But I need to make sure to update only one record per transaction. Familiar with the LIMIT clause from ...
3
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1answer
2k views

fetching externally hosted db's table from within the local mysql server

Let's say we have a mysql database on localhost with table A and table B. Is it possible to fetch details from a 3rd party mysql server to which we have login info and which allows external access? ...
5
votes
1answer
10k views

MySQL Slave replication: Need to determine where replication left off to start slave in correct location

Idiotically I rebooted a machine that is used as a MySQL slave without running STOP SLAVE, FLUSH TABLES first. I had thought MySQL automatically handles all of this during a machine reboot, but ...
3
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2answers
804 views

get column from too many tables in mysql

.I have too many tables X1,X2,...Xn (they might exceed 75 tables) in Mysql DB to represent departments of a very large company. every table has structure something like this desc X1; +---------+------...
2
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1answer
3k views

Why is mysql logging to syslog?

I have installed Multiple MySQL instances and i have two configuration files one for each one is using default location of /etc/mysql/my.cnf. other server i have started like root@ABC-240:/usr/...
3
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4answers
7k views

Can I specify a different disk for a specific MySQL table?

I use my home machine as my personal database for my hobby analytics project. This machine has an SSD for the main drive where MySQL stores its data. It also has a secondary hard drive that is ...
14
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3answers
11k views

How to convert mysql to postgresql? [closed]

I am desperately looking for a conversion tool to convert a big mysql database to postgresql. I need the tool/script to be: Free Works under Linux Simple to use and not buggy You actually tried and ...
3
votes
2answers
8k views

Mysql consumes a lot of memory

Here is my situation. I have an ubuntu server monitored by nagios. recently nagios sends alarms regarding the memory consumption on the server. I logged into the server and executed the top command ...
4
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4answers
14k views

Optimized my.cnf for high-end and busy server

Curretly my main culprit of poor performance is MySQL and I'm not a DB savvy. So far, I've had little luck in optimizing mysql configs on my server, which has a Sandy Bridge processor with 16GB ram ...
6
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1answer
6k views

what are the conditions under which mysql replication might break?

I am running mysql server in master/slave configuration mode. There are multiple slaves replicating from a master. They are working fine and their replication status is monitored. One of the slaves ...
5
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1answer
840 views

Database as a service (DbaaS) over dimensions--performance, scalability, & reliability?

MySql Database as a service: Amazon Xeround Another eg. PostgreSQL Database-as-a-Service. You can get the list of similar products here. Does anyone have details on their performance, reliability, ...