MySQL : Open-Source, Relational Database Management System

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MySQL replication - independent data update on slave

I have an unusual situation where I am migrating websites and their corresponding databases from one server to another. I have a database that is hosted on one server, A, where new records are ...
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35 views

Can I replicate slaves without a dump?

I have setup a new slave in a set and I just want to allow it to naturally cach up to the master and start using the binary log once it has caught up. However, I cannot seem to find anything on this, ...
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Configuration to stop mysql sleep

I am trying to configure a mariadb / mysql instance to stop sleeping when there is no activity for a while. The reason being is that I keep getting the following exception in my java logs when nobody ...
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27 views

Performance difference between two MariaDB slaves

I have a pool of MariaDB servers like this : master (5.5.38-MariaDB-log) slave1 (5.5.38-MariaDB-log) slave2 (5.5.38-MariaDB-log) The two slaves servers run on the exact same hardware (Dell ...
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375 views

Is Data Warehousing possible in MySQL and PostgresSQL [closed]

I am fairly new to DB design and development. My requirement is simple drilldown/slicing based on time and language of words (in a language on a particular day). However, my db is mysql. But so far I ...
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35 views

How can I transfer Mysql data to another computer and add it to an exist database

I'm trying to transfer Mysql data to another computer and add it to an exist database Here is the condition: 1. Computer A, A has a database named 'Test'; 2. Computer B, B has a database named ...
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1answer
14 views

How much memory will allocated for a mysql view

How much memory will allocated for a mysql view,if not how it works,if allocated how much will be allocated.
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11 views

MySQL: Is there any possible way to get notified about mysql-server FOREIGN KEY CONSTRAINT violation during INSERT, if FOREIGN_KEY_CHECKS=0 ?

Plese don't bite me, i'm a newbie here ... So here is the question: Is there any possible way to get notified about mysql-server FOREIGN KEY CONSTRAINT violation during INSERT, if ...
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20 views

Mysql performance tunning [closed]

I have 2 VM : one x.x.x.22 "16G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8Core " and one x.x.x.21 "8G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8core" Now , app is installed ...
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2answers
30 views

what is the difference between mysql community server and mysql cluster

I am starting to look into different database's for different use cases. I see there is a mysql community server and mysql cluster. What is the difference between the two? Are they both database ...
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49 views

is this dead simple query too slow?

I have added and removed a few indexes from my user table and, while testing, didn't see the performance gains I had hoped. As a result, I removed the indexes and tried a simple query to see what my ...
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3answers
49 views

Query to compare the structure of two tables in MySQL

To automate the backup process of one of my MySQL databases, I would like to compare the structure of two tables (current version vs old version). Can you think of a query that can compare two ...
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20 views

(libmysql): (filename not available): mysql_query

Hi everybody im running a game server connected to mysql and it crashes only because of mysql connection with the error in title.. when i dont use mysql and save data as files on harddrive it dont ...
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4 views

(libmysql): (filename not available): mysql_query [duplicate]

Hi everybody im running a game server connected to mysql and it crashes only because of mysql connection when i dont use mysql and save data as files on harddrive it dont crash at all but i cant ...
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0answers
11 views

MySql full text query with truncate sign strange behaviour

I'm implementing a search mechanism on a customer site. I need to find products with "full-text" matching description. However, I noticed a strange behavior. Taking for example two records: (A) ...
3
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1answer
271 views

Is there any performance difference in using a unique index on primary key?

I know there are lost of similar questions to this one, but none that really answers this: Is there ANY difference in performance in using an unique index in a primary key, using a MyISAM table on a ...
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2answers
48 views

How do you update a large MySQL table that's on a server?

I have an application on a web server. The PHP front end for the application queries a MySQL database which has a table that contains 60 million taken domain names. My application queries this ...
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3answers
59 views

Best approach for Legal/Natural can have many Orders

I'm working on this model: where as you may see one NaturalPerson can have many Order and the same for LegalPerson the only difference between NaturalPerson and LegalPerson are a few so in that ...
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38 views

Adding foreign key to MySQL does nothing

I have two systems: a dev system and a production system. On the dev system, I added a foreign key to a table using this statement, which has been created by phpMyAdmin: ALTER TABLE ...
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34 views

Database Migration with Liquibase using different DBMS

Our customer is using Oracle and we want to use MySQL for development. Therefore our MySQL Scheme has to be in sync with Oracle. I tried to use Liquibase, but I get problems at the time of applying a ...
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74 views

Find the closest bar, when searching for a drink

Problem: Find the closest bar that serves the drink(s) I'm looking for. Here you can find the generated MySQL code http://pastebin.com/5Uc2ewUW The API Request that interacts with this problem ...
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1answer
40 views

MySQL replication - slave hangs during ALTER table or BULK update - v5.1.71

We are facing the above mention issue. In this case if we try to STOP SLAVE then it hangs and we even can to restart DB. As I search in google for the same it looks like a bug. Id 38205 in V5.1. My ...
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12 views

How to ensure that another schema in available from the schema the webapp is connected to?

In an existing webapp and database architecture, the application connects to a MySQL instance where several schemas reside, beside the application schema; let's call it app_db. During certain ...
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2answers
40 views

show table name + number of records for each table in a mysql innodb database

How to list all tables in the current database, together the number of rows of the table. In other words, can you think of a query to come up with something like this in mysql? ...
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148 views

MySQL instance stalling “doing SYNC index”

Problem An instance of MySQL 5.6.20 running (mostly just) a database with InnoDB tables is exhibiting occasional stalls for all update operations for the duration of 1-4 minutes with all INSERT, ...
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1answer
26 views

InnoDB compression: memory usage

InnoDB offers table compression for Barracuda-type tables and the recommendation seems to be to "adjust" buffer_pool_size. The documentation is rather vague about the definite impact of compression on ...
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1answer
51 views

Calculating a running balance to store with transactions

I need to put a read-only copy of balance and transaction data from a legacy system, which will only be used to view/print statements. Balance | id | member_id | product_id | balance | | 1 | ...
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1answer
49 views

How to group uninterrupted squences and get min max?

I have table where I am storing some sequential data that indicate occurrences of some event given day. id from_id to_id date 1 2 1 2014-08-01 2 2 ...
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2answers
46 views

#1093 - You can't specify target table 'R' for update in FROM clause

As an attempt to answer Difference data between adjacent rows UPDATE Visits R SET Duration = TIMEDIFF( ( SELECT ReqTime FROM Visits N WHERE N.ID > R.ID AND N.Session=R.Session ORDER BY ID ...
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1answer
15 views

Using file .log.3.gz

I have a file which I need to look at for errors, I got it from someone its extension is mysql.log.3.gz and when I uncompressed it, it has mysql.log.3, It is a log file? And if I open it in text ...
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2answers
158 views

Online Hostel Management System ER Diagram

I have created an ER diagram for an online hostel management system. Please advise me if this diagram makes sense or needs improvement.
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2answers
75 views

How to generate auto increment values for my duplicate column in my sql?

How to display when i was run to find duplicate values from my table at this time i want to add new column in select statement with auto increment values SELECT * FROM tutorials_tbl WHERE Lscno IN ...
2
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1answer
131 views

Difference data between adjacent rows

I have a table (called Visits) with ReqTime DATETIME NOT NULL column AND Duration INT UNSIGNED column. Duration should be set to the difference of ReqTime for two adjacent rows. But Duration is not ...
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1answer
70 views

Query does not use index (according to EXPLAIN SELECT)

Can anyone give me an indication, why this query does not use the Key on the table 'gtg'): ...
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1answer
33 views

How does subpartitioning actually work and what physical files are created?

I can't understand how the subpartitioning works in mysql. I am reading the following example: create table invoices ( customer_id int not null, product_id int not null, amount decimal ...
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2answers
9 views

Mysql top up to 300%

When my table reach 100 000 row mysql %cpu top up to 200% and more. I have a server that run with Debian, 2cpu, 8G of ram and config with Myisam. I have tried different thing in my.cnf but not sure ...
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1answer
53 views

join from different tables gives same result, but it shouldn't

This is the code I'm using and I'm having a problem with it. SELECT `disenos`.*, `votos`.`valoracion`, `usuario_contacto`.`nombres`, `usuario_contacto`.`apellidos`, `users`.`username`, ...
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35 views

Emulating WITH clause in MySQL/query perfomance review

I have never really worked with MySQL queries till this last week. I was tasked with making a simple tool for my department that tracks contacts. Here are the 2 tables and the type of data they ...
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19 views

replication error Error Duplicate entry… for unique key

I have two database that one of them is replicated of another one,my tables have unique key on some column ( NOT primary key ),so if in replication process an Error Duplicate entry..... occur,these ...
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1answer
78 views

Pivot table with MySQL

I'm trying to create a pivot table like output (cross table? Not entirely sure about the difference). The idea is to have rows, columns and summary values (specifically: distinct count). The data ...
2
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1answer
51 views

MySQL CPU & Memory Spikes

Every couple of days, my server's CPU and memory usage spikes up to 100%, making our vBulletin forum almost unusable for 5-10 minutes. CPU is typically at 1-2, Memory at 3GB. During the spikes, CPU ...
3
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1answer
87 views

Row size error with MySQL

I'm running a MySQL server on my Macbook (for testing). Version is 5.6.20 from Homebrew. I started running into "Row size too large" errors, and I've been able to reduce it down to this test case. ...
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2answers
40 views

How to store user's language knowledge (150+ languages) in mysql DB

Users in my website must be able to select languages they know (English, German, etc), so I have a table languages with 150 languages (id, name) and table users (id and a lot of other fields). ...
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39 views

Slow mysql UPDATE with IF() conditions

not sure why I can't even EXPLAIN this query. Mysql refuses to EXPLAIN it. Table contains a million meaningless test entries. Full schema and data dump of the table available here: ...
2
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1answer
62 views

Is data warehouse monitoring same as database monitoring? [closed]

I have a requirement, where data warehouse population is to be monitored. I am in confusion, and needed a clear picture. Is data warehouse different than database? eg. For monitoring database we ...
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0answers
21 views

Mysql syntax error when i add on completion preserve

I have written this event in mysql DELIMITER $$ CREATE EVENT le_drop_database ON SCHEDULE EVERY 1 WEEK ON COMPLETION PRESERVE STARTS CURRENT_DATE + INTERVAL 4 - ...
1
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1answer
22 views

Import multiple CSV fields into one MySQL field

I'm trying to import our CSV data log into our MySQL. The first two fields of the CSV are Date and Time, and I would like to combine that into one date time (which can be searched) onto MySQL. CSV: ...
2
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3answers
189 views

Can I use PHP function strtotime() in SQL queries?

I have this table, and I need to use a PHP function in the query. id time lastTime 1 08:02 2 08:04 3 08:30 I am using this query with the strtotime(), and it's not working: ...
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1answer
37 views

Translating MySQL query to PostgreSQL

I have a query which works fine in MySQL, however when I try to recreate the same query in PostgreSQL (same DB structure) I just get a syntax error. MySQL: SELECT ticket.queue_id, queue.name, ...
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What is the difference between Row and Table Expressions in MySQL

Can anybody explain with example what is a Row and Table expression and what is the difference between them. Any example for clarification will be appreciated.