MySQL : Open-Source, Relational Database Management System

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primary key: username+current time or serial

I need to choose a primary key, but I'm not sure what the best option would be. Currently I'm in a scenario where a user has machines (workers) calculating hashes. For each user I track the current ...
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4 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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464 views

mysqlbinlog failing with “ ERROR 1032 (HY000) at line 48: Can't find record in `` ” Error

I am facing some issue with PITR restore using mysqlbinlog . It is failing with the following error . # mysqlbinlog mysql-bin.000035 | mysql -u root -p db Enter password: ERROR 1032 (HY000) at ...
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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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1answer
11 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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39 views

SQL File Upload to MySQL Server

I'm fairly new to databases. I want to upload a .sql file to a mysql server. However the database I want to update contains many .frm .myi .myd files. Should I delete those files and replace with the ...
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1k views

How to add 'root' MySQL user back on MAMP?

On PhpMyAdmin, I removed 'root' user by mistake. I was also logged in as 'root'. How can I add the user 'root' back, on MAMP?
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15 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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269 views

mysql cluster table full error

I installed a new mysql cluster on windows (for evaluation). I created a table using command below. After I insert just over 1 million records into the table it gives me the "table datadump is full" ...
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66 views

What are possible causes for consistently volatile INSERT performance in MySQL tables?

I have a Java program running on a VM that is sequentially feeding a queue of single row INSERTs through a single connection to a MySQL server on the same VM. The queue execution is not artificially ...
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30 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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44 views

MySQL 5.1: change datadir variable value in my.cnf

Below is my system configuration: OS: RHEL5 MySQL: 5.1.73 Default datadir=/var/lib/mysql/ But, the above directory has space crunch. So, I decided to change the path. I found /u000 directory has ...
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3k views

How to find dependencies on a table in mysql 5.0?

I am trying to drop a table in MySQL but its complaining about "Cannot delete or update a parent row: a foreign key constraint fails"... Questions Is there a way to find out all the table ...
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273 views

Mysql - How to Optimize Retrieval Time in a Table

I have query like this! which has 200 million Records in a single table.. I am using BTree Indexes in my table... mysql> select COUNT(DISTINCT id) from [tablename] where [columname] >=3; ...
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1answer
178 views

Is this amount of disk IO expected with MySQL?

I am running MySQL 5.5.34 on an Amazon EC2 micro instance with EBS (elastic block storage). The instance has been running for around 10 days and according to Amazon I've accumulated around 8.5 ...
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16 views

MySQL instance stalling - due to InnoDB log flushes?

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, UPDATE and ...
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35 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
99 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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104 views

Query multiple rooms with different conditionals (Adults, Children)

I have a simple query where I select available x Rooms with x Adults + x Children per hotel that matches a date range, but I'm having a hard time trying to figure out how to query a list of rooms per ...
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17 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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62 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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1answer
2k views

MySQL requires FORCE INDEX on huge table and simple SELECTs

We have an application which stores articles from different sources in a MySQL table and allows users to retrieve those articles ordered by date. Articles are always filtered by source, so for client ...
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50 views

Issue when connecting to open shift via mysql workbench on Mac

I am trying to connect to open shift with mysql workbench on an iMac. A colleague has shown me his setup on Windows which looks exactly as follows (other than the usernames / passwords changing) ...
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2answers
62 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 ...
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86 views

Mysql replication is enabled but stuck at “waiting for binlog to be updated”

I have set up replication between an existing database (server-id=23), and a new one (server-id=51). I have followed the steps in this stackoverflow question, but replication is not happening. On ...
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1answer
14 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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123 views

How to improve the performance of SELECT queries with multiple JOINs on a 50GB database hosted on AWS m3.medium MySQL RDS?

Example query: SELECT p.ListAgentEmail, p.ListAgentFirstName, p.ListAgentLastName, p.ListingKey FROM Property_RES AS p INNER JOIN Property_RES_COUNTIES_OR_REGIONS ON ...
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92 views

Query only for the first n results of like

What I'm trying to accomplish is a huge speedup (read: incremental results) when searching a database with a like operator which is kind of a last resort, if everything else already failed, to come up ...
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81 views

JOIN on variable number of columns

I have the two tables courses AND something_about_courses: courses course_code course_session course_type something_about_courses course_code course_session some_description To ensure that I ...
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1answer
45 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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2answers
159 views

Hierarchical Structure

Every single user has say, 3 of GROUP_A, 10 GROUP_B's per GROUP_A, and 20 GROUP_C's per GROUP_B. And each of the 20 GROUP_C's involve lots of inserts/deletes... I'm not an expert, but I've done ...
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63 views

Mysql 5.6.17 drop large table locks the server for minutes

We run Mysql 5.6.17. Dropping a large InnoDB table 10GB caused the whole server to lock for about 40 seconds. We have 55GB innodb buffer pool size. I read bunch of old bugs that could be the source ...
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1answer
578 views

Designing database with Category and Tags for Posts - Seeking for guidance/advice

I'm not really a database novice but I'm not an expert either. Problem: I'm having this difficulty on designing my Post, Category and Tags relationship. I've read Normalization many times but could ...
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1answer
99 views

Please suggest my.cnf configuration based upon mysqltuner findings

I have been facing a lot of slow browsing on my site nerdeky.com. My server administrator suggested me to use mysqltuner.pl to find and tune my databases. Can anyone select me what should be the good ...
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1answer
25 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
146 views

Problem in Fetching Result set in Desired Format

I have 2 tables having the following columns Person ------ person_id, first_name, middle_name, last_name Items ----- person_item_id, person_id, item_type, status, ordered_date The query is ...
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46 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
690 views

Table Design - User Management

I have designed a database design for a simple User Management System, this system consist of the following things, User - A user may be a Vendor / Employee / Buyer. User - A user may have more than ...
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1answer
732 views

MySQL - run SELECT statement on another server without defining the table structure

In MySQL I can query information on another server using federated tables, as long as I've defined the same table structure locally. In MS SQL Server, however, I can run any SQL statement against a ...
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34 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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1answer
126 views

How can i import 150GB database after deleting ibdata1,logfile in MYSQL?

I have 150GB database and my ibdata1 file size is 240GB so i want shrink the ibdata1 file so for that i have to export the DB and then drop the tables and then stop mysql, delete the ibdata1 file and ...
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4answers
960 views

How can I replicate some tables without transferring the entire log?

I have a mysql database that contains some tables with private information, and some tables with public information. I would like to replicate only the tables containing public information from one ...
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2answers
41 views

MySQL user without SUPER privilege

This may be a simple question and may not be the right place to ask but I couldn't find any useful information from Google. Here is my question. When creating users in mysql using grant all ...
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1answer
2k views

MySQL: Lock wait timeout exceeded

I have a developer that has been trying to alter a large table (~60M rows). Via LiquidBase/JDBC they're running ALTER TABLE foo DROP FOREIGN KEY fk_foo_1; Today while it was running I checked in ...
2
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1answer
38 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 ...
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1answer
46 views

Need help with data model

Schema does not list all fields, but only the relevant ones User adds credits/funds to his account using paypal or Internet Banking (which has to be verified manually, and approved, so the 'status' ...
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3answers
115 views

Why MAX() of SUM() giving wrong output?

I have a table employee id name salary city 1 ram 50000 c1 2 sham 20000 c2 3 jadu 80000 c1 4 madhu 90000 c4 5 hari 10000 c2 6 gopal 34000 c3 7 ...
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64 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 ...
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3answers
127 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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204 views

How to migrate data from SQL database to MySQL including flat files?

one of my friend has asked some asp developer to make online application where user can upload files also. jpg, doc, pdf and all these files are saved in SQL database as flat file. Now my friend asked ...