MySQL : Open-Source, Relational Database Management System

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7
votes
3answers
717 views

Should I separate frequently updated columns?

I have a users table that contains users' information and a column named credits that is frequently updated. On index page I'm showing list of users with basic user information but I don't need ...
1
vote
2answers
202 views

avoiding unique key collisions across tables

This might be related to the idea of data warehousing, but i'm not sure, though it is extreme theory. We have a table where records get written to first, let's call it tbl_recording which looks like: ...
3
votes
1answer
4k views

Move ibdata1, set innodb_data_file_path

I am in a bit of an awkward situation right now. I have a database with a few large InnoDB tables, one of which is about 145 GiB. I have been running a lot of maintenance on this table in particular, ...
0
votes
0answers
11 views

MySQL Recursive query

I have a table EventScheduleID Col Level 1 - 0 2 - 0 3 - 0 4 1 0 5 - 0 6 ...
1
vote
2answers
58 views

Managing constants changes to database

Here's the deal, I'm in charge of creating a website that will host small web apps. This apps will be photo contests, creatives sentences and other similar gibberish. The deal is, since apps we'll be ...
0
votes
2answers
107 views

why does mysql query running slower on server?

select glpi_tracking.id AS gi, glpi_tracking.date AS gdate, glpi_tracking.closedate AS cdate, glpi_tracking.contents AS gc, glpi_followups.tracking AS gft, glpi_followups.date ...
6
votes
3answers
6k views

Amazon RDS for MySQL vs installing MySQL on an Amazon EC2 instance

At work, we host all our webservers on Amazon EC2 and usually have used MySQL databases installed on the same box as our Apache webserver, and communicated with them on localhost. We now face a need ...
0
votes
1answer
70 views

Increase performance WITHOUT adding indexes

I'm having a rather large table (350MB, 1.3M rows) and there are dozens of queries arriving at this table every second. Most queries are super-fast thanks to indexes - but some others aren't. ...
2
votes
1answer
268 views

Best Practices for Creating and Deleting Records in MYSQL

I'm fairly new to working with databases, but I've currently have a webCrawler that I've written in C# using MYSQL database. The crawler is frequently writing and deleting records from the database ...
0
votes
0answers
10 views

Can I use xtrabackup to import a database without altering others?

Context: Each time a demo branch is built, I want to download a copy of the prod database and setup it onto the demo server. This way under the MySQL I have X database corresponding to X demos. I ...
0
votes
3answers
40 views

Duplicate values

Here is my table : PlayerId NoOfTeams 1 3 2 2 3 2 4 NULL 5 NULL I want to display PlayerID having same No.OfTeams including NULL values. Could any one please ...
1
vote
0answers
11 views

Multilanguage category structure - standard vs. normalization?

I'm building a multilingual application and I need some advice on how to structure the table. Basically I have a category table based on nested set. There are 4 languages and I plan to enlarge this ...
5
votes
2answers
132 views
+50

Is this update, select combination query thread safe?

I have a table called seats, which has a schema like this id,taken For each user, I take a random untaken id and assign to that user, here for simplicity say, I make taken =1. The query I am ...
2
votes
4answers
4k views

Mysql innoDB write operations are extremely slow

I'm having serious performance problems with MySQL and the InnoDB engine. Even the simplest table makes writing operations (creating the table, inserting, updating and deleting) horribly slow, as you ...
2
votes
1answer
126 views

Best Indexing Strategy for Query with Equality[A], Range[B], Group By[C], AND Order By[count(P)]

I have a poorly performing query: SELECT user_id, count(item_id) as count FROM table items WHERE category = 'magazine' AND created_at > 1384754400 GROUP BY user_id ORDER BY count(item_id) desc ...
0
votes
0answers
8 views

MySQL Query lock acquisition order

I have a query that joins across many tables. In one of our workflows another query deadlocks with that query. Iv'e read that one step towards prevention of deadlock is to acquire locks in the same ...
2
votes
1answer
133 views

Peer Review of Database Design

I'm working on a movie inventory database. This is a personal side project for me. I can use what I have, but I would like to make it the best design that I can while learning more about databases and ...
0
votes
1answer
221 views

Cross tab query with concat field

I want to create a cross tab query for my table.but when i am using concat i am unable to get ouput succesfully.can any one help me with my query. SET @sql = NULL; SELECT ...
0
votes
1answer
51 views

MySQL-How to find that value in a column is subset with all other values in same column multiple time

I have a table named as Team where table contain 3 column (ID,Team,Task). Its datatypes are (INT,VARCHAR(255),INT). Below you will find a sample table where I would like to perform the query on column ...
0
votes
0answers
18 views

Signal in MYSQL procedure with parameters?

Following is from my MySQL dump DELIMITER $$ CREATE DEFINER=`root`@`localhost` PROCEDURE `test`() SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Mobile Number Exists'$$ CREATE ...
1
vote
0answers
16 views

Strange MySQL replication error 1146 (Table doesn't exist)

I'm getting a very weird MySQL replication error No. 1146 for a REPLACE INTO query on a slave host replicating all tables in all databases from a master, and I'm having a bit of a hard time ...
1
vote
2answers
142 views

MYSQL joining 3 tables with left join

I have these tables: pupils: (id_pupil, name, surname, email, user, pass, level, class) incidents: (id_incidents, date, time, type_incident, comments, id_pupil, id_user, subject, id_trimester) ...
0
votes
0answers
11 views

New To SQL and looking for some advice [on hold]

I have just finished my first SQL server class and would like to continue learning how to develop databases. The problem that I am having is that I am a noob at this, and I cannot think of a simple ...
0
votes
1answer
138 views

MySQL slave stuck at 'System lock' most of the time, high CPU usage

Let me describe what we are facing now: We have a MySQL Master-Slave, Row Based Replication setup and at the moment, the slave is stuck with a perpetual System Lock. The Master is an active server ...
1
vote
0answers
20 views

Migration error: “Invalid date literal detected” when reading decimal

I'm attempting a migration from MSSQL to MySQL and keep coming across a "Invalid date literal detected" error when reading certain decimal columns. I'm running the following (all up-to-date as of ...
1
vote
3answers
152 views

How to remove master role from MySQL server

I have 2 MySQL servers, one is the master and other one is slave, that's all good. The problem I have is that the slave is also set up as a master. I would like to disable or remove the master role ...
0
votes
0answers
7 views

In MySQL 5.6, schema changes in master blocks the slave?

I have a question with a MySQL 5.6 master-slave setup. If you were to modify the master's schema with an ALTER TABLE SQL query, when the slave tries to execute that ALTER TABLE statement too, would it ...
0
votes
2answers
38 views

Is it ok to have 40+ columns in a table

I am currently re-designing some of DB's for a project. There is one DB in particular that is giving me a little of a headache. The idea is that for every client_id and date (client_id + date would be ...
0
votes
1answer
71 views

MySQL add few column exception for TRIGGER UPDATE FOR EACH ROW

How to effectively add column id, name exception for trigger: CREATE TRIGGER updated BEFORE UPDATE ON table1 FOR EACH ROW SET NEW.date=NOW() so that date=NOW() will be affected on updating any ...
1
vote
1answer
70 views

MySQL: IF statement check is a table exists

I run in the following issue and can't figure out how to resolve it. delimiter # create procedure pr1() begin declare v1 double default 0; start transaction; ...
0
votes
2answers
1k views

How to join two result sets from same table with different conditions on same column?

select * from unit_of_measure; +--------+-----------+--------+------------+--------------+-----------------+-------------+---------------+------------------+ | uom_id | uom_name | symbol | created_by ...
0
votes
1answer
667 views

Why does max_connections in my.ini not match concurrent connections in Mysql instance config wizard?

MySQL 5.1.x | Windows Server 2003 Can someone please clarify why max_connections in my.ini is much larger than the manual value I specify in the Concurrent Connections Dialogue? For example, if I ...
0
votes
1answer
133 views

Mysql closing immediately after new installation

I am using mysql as an backend for my webapp ,the software ran without any glitch but today it gave unexpectedly ERROR:2003 i tried many solution on the internet but none worked. so reinstalled the ...
0
votes
0answers
9 views

Are ZRM (Zmanda Recovery Manager) incremental backups reliable?

I had an issue while restoring incremental backups and I'm wondering if they are reliable. I'm making weekly full backups and daily incremental backups and I needed to restore a single database after ...
1
vote
1answer
68 views

Custom Collation on MySQL Unknown

I've created a new collation as per the instructions mysql. In fact this tutorial was the exact use-case I needed. I've added the collation, and restarted mysql. When I try to run ALTER TABLE ...
1
vote
0answers
11 views

Sysbench insert data between a given range

I was trying to insert 1000000 records of data into 1000 tables in sysbench. But after installing about 278, sybench just crashed with the following error: FATAL: failed to execute function ...
0
votes
2answers
4k views

MySQL shutdown unexpectedly

2013-09-09 10:21:44 5776 [Note] Plugin 'FEDERATED' is disabled. 2013-09-09 10:21:44 1624 InnoDB: Warning: Using innodb_additional_mem_pool_size is DEPRECATED. This option may be removed in future ...
2
votes
1answer
19 views

What is the Best way to set Disaster recovery setup for percona Xtra DB Cluster?

We do have a Percona XtraDB Cluster(Master-Master-Master) setup in one country. Now we want to setup a disaster recovery setup in some other country. Please provide us the best possible ways to do ...
7
votes
5answers
15k views

Why does MySQL say I'm out of memory?

I was trying to execute a fairly large INSERT...SELECT in MySQL with JDBC, and I got the following exception: Exception in thread "main" java.sql.SQLException: Out of memory (Needed 1073741824 bytes) ...
1
vote
3answers
33 views

MySQL select with between optimization

I got issues with some geo IP query. So basically here is create code of table: CREATE TABLE `geo_ip_city` ( `id` INT(5) UNSIGNED NOT NULL AUTO_INCREMENT, `begin` BIGINT(20) NOT NULL DEFAULT ...
0
votes
0answers
34 views

Select these if this, or select these…

Here is my problem: organization_category.id can be either 1,2. With organization_category.id = 1, then the organization_type.id can be 0,1,2, or 3. With organization_category.id = 2, then the ...
1
vote
1answer
16 views

How to Paginate a MySql Ranking Query

I have the following ranking query working fine with a limit of 25 records per page, it shows 1st - 25th for the first 25 records, but when i go to the next page, the rank stays the same 1st - 25th ...
0
votes
1answer
14 views

Select all results from two independent tables

I have two tables: Comments -------- id comment_content time_stamp Activities ----------- id activity_content time_stamp And I would like to combine the results from both, ordered by their ...
0
votes
1answer
82 views

getting “table is full” error even if the table size is much smaller than tablespace

Currently I am using MySQL NDBCluster 7.3.5. I have created one UNDOFILE hhme.dat with INITIAL_SIZE=200m. Also one tablespace hhmefep_tbs with DATAFILE hhmefep_tbs.dat having INITIAL_SIZE=500M ...
0
votes
0answers
12 views

upload updated details in excel to mysql database

I have a batch file which updates the excel file by adding the latest values to it. The details are already there in the MySQL as a table. Once the details are updated. For eg after the end of day ...
0
votes
1answer
76 views

A single, simple update takes 10+ seconds

We are running MySQL 5.1.71-log and have a table with 2.7 million rows. Simple updates to it are regularly taking more than 10 seconds to execute. The table structure is: CREATE TABLE `person` ( ...
0
votes
1answer
22 views

How to update Large table in MYSQL

I want to update a large number of rows (more than 80k) from an external data source (from file) into an existing mysql table. This database is InnoDB. Database structure: CREATE TABLE IF NOT EXISTS ...
0
votes
1answer
19 views

Newly created user has rights on MySQL database

I use the root to create a new user, like this: I have no more operations on it. Then I use this user to log in: I try to do some operations like this: Here "test" is a database which I created ...
0
votes
1answer
144 views

Mysql can't write to filesystem

I need to output some queries as csv files. The directory is in the webroot and I want it to be writable by apache too, so I'm trying to add mysql to the www-data group (on Ubuntu). I thought this ...
0
votes
1answer
109 views

Very slow update with subquery (different tables)

I run this query to update "domains" table based on "log" table: UPDATE domains SET domains.mx_collected = 0 WHERE domains.domain IN (SELECT log.mail as domain_name FROM log WHERE `time` >= ...