MySQL : Open-Source, Relational Database Management System

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How to profile individual queries using PERFORMANCE_SCHEMA

I've been looking at SHOW PROFILES, which seems ideal for what I am doing. However, I've noticed a warning that SHOW PROFILES is being deprecated and that PERFORMANCE_SCHEMA should be used instead. ...
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MySQL Partioning: Is there a performance tradeoff between number of partitions and size of each partition?

I have a large table (several 100 million rows) that I would like to efficiently partition. My question is whether there is a tradeoff between partition size and number of partitions. As far as I ...
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215 views

Improving database design for category based site

I'm working on a site that gets about 30k visits a day and it makes use of a lot of queries which uses UNION's over about 45 different tables, these tables generally range from about 15k rows to about ...
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251 views

MySQL GROUP BY and ORDER BY giving inconsistent results

I'm currently working with WordPress, and I've added a new meta value which is a number between 0 and 30. Zero is ignored and up to 30 need to be organised in order and only the latest (based on the ...
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162 views

Get all comment.message, status.message, users.* and profiles.* where users.user_id exists in friend.friend_id or friend.user_id

I need some help building this query because it's a bit complicated at least for me. I need to get all comment.message, status.message, users.* and profiles.* where users.user_id exists in ...
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859 views

SQL query optimization in Prestashop e-Commerce solution

I'm working on a layered navigation module within Prestashop e-Commerce solution. I'm trying to optimize a SQL query which creates a temp table during execution. I think this is creating a ...
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107 views

Why do we need myisam spatial extension anyway?

If just to determine whether a point is within a rectangle, What is wrong with this query? EXPLAIN SELECT DISTINCT TB.ID, TB.Latitude, TB.Longitude FROM TableBusiness AS TB WHERE ...
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216 views

mysql server is not sending result set back after query execution to client and staying in sending data state

When I pass a query from my Java application to mysql server, it stays in Sending Data state and not returning result set back to application. When I execute the same query in SQLYog directly, it ...
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894 views

Tables don't exist after MySQL restart

I recently made changes to optimize performance for InnoDB engine-based DB and soon after when restarting I encounter into the following strange behavior: I have some tables with data in them I made ...
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165 views

Enforce a hard limit on write execution time during Amazon RDS write stalls

I am trying to recover from the situation where Amazon RDS write operations stall (some discussion on why this is here). If I show full processlist, I will see something like this: 318263 myapp1 ...
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815 views

stored procedure returns ERROR 1305 (42000): FUNCTION does not exist

I have a stored procedure and function as below CREATE PROCEDURE ProcName() begin .... DECLARE curs CURSOR FOR select A.PList, B.nid from persons A inner join articles B on A.aid=B.id; .... ...
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794 views

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2?

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2 ? updated to answer the 3 questions: mysql> show variables like 'version%'; ...
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2 views

MySQL Utilities seems outdated?

http://dev.mysql.com/downloads/utilities/ has MySQL Utilities 1.4.4 for Mac OS X 10.7. Is this still updated and recommended to use along with MySQL Workbench? I'm at the latest MySQL Workbench 6.1 ...
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5 views

Can having a LIMIT on DELETE degrade performance dramatically?

I have a database project in php and mysql. For, hopefully redundant, data security I added a LIMIT 1 to the delete($uniqueID) php function we use. Nobody cared because records really aren't ...
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2 views

MySQL starts from shell but doesn't start from MySQL Workbench

Being in need for MySQL database for a Django project i performed its installation from official website. It starts well from bash shell though "sudo service --status-all" shows status like this - [ ? ...
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11 views

EXPLAIN (with subqueries) is giving results I don't understand

I have a query that relies on a subquery, and that subquery relies on another subquery. When I run an EXPLAIN on the full query, in does a full table scan of the table in the primary select. However, ...
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19 views

Schema for multi-account database

I'm building an app which will have accounts for organisations leading to organisation.myapp.com subdomains for their account access. I'm putting together the schema for it and I have a few ...
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13 views

MySQL Cluster lock wait timeout exceeded when trying to deal with huge amount of queries

I'm trying to deal with many connections and sometime I get following error: ERROR : Lock wait timeout exceeded; try restarting transaction The bigger number of queries the least number of ...
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16 views

Connect to a Remote MySQL

I'm trying to connect to a MySQL remote Server but I always get: RROR 2003 (HY000): Can't connect to MySQL server on 'IP' (111 "Connection refused") I follow this rule in the remote server GRANT ...
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22 views

Insert results of concat

I have a table with 4 columns: ID ORDER_ID QTY VALUE 1 153 1 0 2 476 1 0 3 453 9 1 4 719 2 2 ...
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8 views

MySQL: What are the pros and cons of running with engine=Memory vs on a memory-mapped filesystem?

What is the difference (in terms of read and write perf, alter tables, backup and recoverability and consistency) of running a MySQL database on a memory-mapped filesystem vs with ENGINE=MEMORY
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34 views

Nesting multiple INNER JOIN within LEFT OUTER JOIN in sql on deifferent side of keyword

I am having some problems with one of the question's answered in the book "SQL FOR MERE MORTALS". Here is the problem statement Problem Statement Here is the Database Structure The Database ...
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20 views

Multiple Queries with overlapping results and column level permissions

Sorry for the obtuse Title, I'm having a hard time knowing how to summarize. I'm trying to do this with pure SQL(mySQL) and server-side(Perl) data manipulation. A user table is defined: id, uid, ...
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19 views

Correct Schema Design for form builder?

I'm attempting to build a form builder app that allows users to: signup build a form store the data from that form into this db. I have designed the following schema: ...
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49 views

Combine two mySQL sum queries into one which use different where clauses

I have two sum quires referencing different tables in mySQL. How can I combine the two in order to calculate the difference between the two values for each user in the database? Query 1: SELECT ...
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18 views

How to change the domain name or IP address in mysql database in every tables

I was using Openfire chat server in Ubuntu, whose IP address was 192.168.1.15. Then, I wanted to move it to other ip (192.168.1.55), so i took a backup of my database. The database I was using is ...
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27 views

Moving datadir OK start, but socket error for mysql client

I'm trying to move my MySQL datadir from /var/lib/mysql over to /home/mysql (an ssd drive as I'm having iowait issues on /var/lib/mysql when MySQL is running on that drive). The OS is CentOS 5.6 ...
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8 views

Logging all user actions

I'm creating a community-driven project and, of course, I want to be protected against spam or evil users. In case of undesirable changes in the DB I would log all users' actions ...
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28 views

Result of query not showing in phpmyadmin

I have a 500,000 row database that I am running a reasonably complex query on: SELECT yfog, (SELECT AVG(yds) FROM pbp_yards_gained p2 WHERE p2.yfog=p1.yfog AND type = ...
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14 views

Pasting into PHPMyAdmin

This is probably really simple but I have had a look on the web but can't seem to find an answer. I am experimenting with MySQL + PHPMyAdmin on a WAMPserver stack and was saving queries in Excel When ...
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16 views

What is safe way to restore mysql database?

When database is online. I want to restore dump file to it. Here is my plan: set global read_only=ON use root with super_priv to drop all databases do restore all databases set global read_only=OFF ...
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14 views

mysqld: page allocation failure. order:3, mode:0x20

I've been running a mysql server in production for some time, lately the db has been locking up at around 10:30 every day. There's no cron jobs running at that time or anything like that, and I'm at a ...
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7 views

MySQL replication: Understanding content of binlog

I am using MySQL replication with GTID. I did mysqlbinlog to see some binary log. This is a section in binary log that I am considering: SET @@SESSION.GTID_NEXT= 'servre-uuid:248283'/*!*/; SET ...
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27 views

SOLVED:MySql: how do I insert a large data set into existing rows automatically?

I'm revising a static website and striping via grep all links, titles, etc. to put into my mysql database. Since it's 400+ links/titles, I just load the text file of titles and then links with a ...
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22 views

MySQL replication working, but data is out of date

I'm trying to figure out why even though SHOW SLAVE STATUS isn't reporting any errors, nothing is replicating (see below): both nodes are running: mysql> SELECT VERSION(); +------------+ | ...
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12 views

MySQL upgrade steps - review

I read the MySQL upgrade documentation and the upgrade questions in stack exchange and have a fairly good understanding at this point. I am an accidental MySQL dba and this is my first upgrade and ...
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13 views

MYSQL Stored Procedure Problem. Need Help

MySQL Stored procedure: Delimiter $$ DROP PROCEDURE IF EXISTS spGetCompanyNames $$ Create procedure spGetCompanyNames (IN Employer nvarchar(75), Out Employer_Namee nVarchar(75)) begin Select ...
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26 views

MySQL select query runs forever in Toad

I'm trying to run a simple SELECT query in Toad (for MySQL 7.2.0.2922). SELECT * FROM sometable When I click execute (or press F9) a small timer shows up in the status bar (bottom right) and it ...
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17 views

Conditional value lists in MySQL

apologies in advance if the language I use here is insufficiently specific. Please let me know if there's anything that I can clarify. Does MySQL provide a means of creating conditional value lists a ...
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17 views

Text comparison select query needed that finds most whole word matches within larger string

I have a database of products, many with similar names. For example... iPhone 5s (GSM model) A1533 iPhone 5s (GSM model China) A1518 iPhone 5s (GSM model China) A1530 iPhone 5c (GSM model) ...
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Markup Languages and SQL Queries

I need to store some metadata in an MySQL database. This data will need to be stored in some form of markup language and reside in a 'meta_data' field on a table. I will need to run searches ...
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38 views

Show single value of one column for multiple rows of other columns

I have a SQL query which displays my data results like this. date emp_id emp_name spent_hours 19-08-2013 1024 jack 10 19-08-2013 1024 jack 11 19-08-2013 1024 jack ...
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27 views

Auto increment holes in primary key - any issues?

I have an application that is creating large holes in the auto incremented primary surrogate key to the table as it uses lots of INSERT ... ON DUPLICATE KEY UPDATE queries. I'm looking into changing ...
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21 views

How do triggers work on partitioned tables?

I have partitioned a table on the basis of a column. This column can either have 0 or 1. So, only two partitions (p0, p1) have been created internally. On this table there are 3 triggers which execute ...
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37 views

Copying a table with its structure, indexes, and associated triggers?

I have studied this post on Stack Overflow: Fastest way to copy a table in MySQL. But no answer is copying everything like the table's structure, data, indexes as well as associated triggers. Is it ...
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8 views

Database for large dynamic network graph - best practise?

I am constructing a MySql database which is to contain data for a large network graph. There will be thousands of nodes and ten thousands of edges. The nodes and edges will be assigned a category. ...
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26 views

Previously inserted rows disappear at call of PHP script

I am developing a server-side portion of a sport manager application using MySQL (5.1.67), with InnoDB as storage engine, and PHP (5.3.3). When I try to execute a script containing any kind of query ...
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14 views

self join of single table to find time difference of adjacent rows of a single column which are not in sequence

I want to find the time difference between two adjacent rows of a single table which are not in sequence.i made a self join of table and tried but i did not achieve what i need .can anyone please help ...
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8 views

Load data from file only for specific column based on other column value

I am familiar with basic usage of 'load data local infile' and importing specific columns only. What I want is however to import a single column from file based/related on data from another column. So ...
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66 views

hot/live sql backup

please excuse my ignorant question as I am still fairly new to database things so I have a mysql database and a part of it has file with average size of 10M I store them in their own directory and ...