MySQL : Open-Source, Relational Database Management System

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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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24 views

Latitude and Longtitude Distance Calculation

I'm using MySQL and I am trying to calculate the distance in meters between two different longitude, latitude coordinates. I wrote a stored function in MySQL but it calculates just 1 for each row in ...
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1answer
1k views

The InnoDB log sequence number is in the future

Our site was getting intermittent database errors and I asked my webhost to check what's happening. After some inspection they found that the database has few issues and tried repairing it. Finally I ...
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1answer
10 views

Problem with mysqldump and view

When using mysqldump to backup MySQL, I got following error. mysqldump --all-databases --routines >> all.sql mysqldump: Couldn't execute 'show table status like 'hdkien'': SELECT command denied ...
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2answers
60 views

Why is MySQL not using the index with the higher cardinality?

I have an index called source with cardinality of 1122 and a second index called state with cardinality of 22. MySQL keeps using the state index when when query SELECT C1 FROM tbl WHERE source = 'x' ...
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30 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 ...
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+100

MySQL schema for recurring events - Query by specific date

I've just asked this exact same question on stackoverflow so apologies for cross posting but I only just noticed dba so thought I'd ask across here as well. I'm just about to start putting together a ...
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1answer
272 views

How do I restore a SQL backup, while excluding a specific table?

How do I exclude a specific table during a SQL backup RESTORE operation? My question is specific to restoring a backup sql file. I am using Putty and bash server.
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?deactivate facebook for multi-site forcing reactivation site-wide? [on hold]

I am connecting to a remote mysql database of my wordpress-website using SSH and mysql-workbench, and have found "key 32228 - facebook activated - wp_databasetab3_changes_tracker". Can I deactivate ...
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1answer
72 views

Select different time

I looked on the internet and I found your post on the stackexchange. I will try to explain in more detail what we really need I do not know well to write English It is a system for airporttaxi id ...
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2answers
37 views

How to stop the execution of a long running insert query?

I've executed an INSERT INTO ... SELECT as a job on my MySQL instance and then I realized that number of records that is selected by the WHERE condition is more than my patience. It's already taken 12 ...
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Check for table corruption

I monitor MySQL databases by querying various things remotely. I recently came across an issue where by a table had become corrupted but I did not know about it until the daily mysqldump failed. Is ...
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3answers
57 views

How MongoDB indexes differs from MySQL indexes?

I am a newbie to MongoDB. I know how Indexes works and what it's importance in MySQL. Are MongoDB indexes are the same as MySQL ?
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1answer
15 views

MySQL query using left join on two inline views not returning rows without values in second view

For some reason when I execute the code below I'm only getting results back that have sku in both views. I thought this should give me everything in the first view and add the content from the second ...
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0answers
16 views

What is a loose index scan?

I was reading that MySQL can not use an index on 2 range conditions due to not having a "loose index scan" What exactly does this mean? Is it related to the underlying or the implementation of the ...
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1answer
22 views

How to prevent crashes connected with dropped tables during mysql import?

I have made a mysql dump with mysqldump, tables are dropped and re-created with DROP TABLE IF EXISTS `users`; CREATE TABLE `users` ( However for a read-intensive database I sometimes get crashes ...
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218 views

multiple connections on MySQL database with no users on httpd

My database seems to have many open connections despite having no users on httpd. mysql> SHOW PROCESSLIST; ...
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2answers
14 views

Mysql Master Offline

In a unidirectional Master-Slave setup, should the slave be manually stopped in cases where the Master is offline due to Maintenance, Crash etc. ? Or should one just leave it so that it keeps trying ...
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17 views

Optimizing a slow MySQL query

I'm trying to optimize a ~100GB database. All data values are in one single innodb table, is this bad? Here's what a common query looks like: SELECT `CensorCode`, `LocalDateTime`, `UTCOffset`, ...
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1answer
18 views

Is it faster to load several small files, or one big file?

We have a 26GB file that we have to load into an empty table. I was curious, is it faster to load nine 3GB files or one 26GB file? Or is there no difference?
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2answers
956 views

Replication on MySQL server

I had to stop the slave server to test something. After I started the server again there is a problem with replication on MySQL server On the problematic server mysql> SHOW SLAVE STATUS\G ...
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1answer
20 views

What is the difference between uniqe index/unique/unique key/unique constraint keywords?

I am using mysql 5.5.16 What is the difference between the following DDL statements? 1) create table sql_query ( id int not null , query_text varchar(21826) not null , query_md5 ...
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1answer
89 views

Does MySQL load the entire row into memory, or just the columns used in WHERE, ORDER BY and GROUP BY?

I have a table that isn't very large row wise (in the 100ks range), but that contains a lot of raw data that is very large in size. Despite having a relatively little number of rows, it's around ...
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4answers
485 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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1answer
22 views

Fan-In replication 4 Master -> 1 slave

I am trying to merge 4 source db's (one for each region) into a global db. We use ID ranges as primary key on the tables in each region and so the merge should happen nicely. I have a fairly high ...
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1answer
1k views

“Can't find file mysql/plugin.frm” when starting up MySQL

When I start my MySQL server, I get this error: /usr/libexec/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13) [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create ...
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1answer
22 views

How can I optimize a big query when EXPLAIN hints don't work?

We have an application that uses MySQL Ver 14.14 Distrib 5.5.35, for debian-linux-gnu (x86_64) using readline 6.2, which esentially manages lots of data from lots of people over lots of tables and ...
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1answer
22 views

How can I rewrite the following removing the date_format function?

I have a table with a column when that is of type datetime. I am doing the following filter which can not use and index: AND DATE_FORMAT(t1.when, '%Y-%m-%d') <= LAST_DAY(now() - interval 1 month ) ...
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20 views

MySQL Query for combobox

I have two tables in my database.namely books and bookidofid. where bookidofid from books table is referenced to bookidofid from bookidofid table Table books ...
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2answers
173 views

MySql InnoDB tables are missing after restarting

I had a MySql database with a few InnoDB tables. After restarting the server, and starting MySql Server again, I connected to the MySql Server using MySql Workbench, and couldn't see the database at ...
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1answer
138 views

MYSQL Timezone support

We are having a shared hosting plan and they are saying that do provide MYSQL Timezone support in a shared hosting plan. I can create timezone related tables in our database and populate them with ...
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1answer
108 views

Debugging error report percona 5.6

I'm running percona 5.6 on a new centos 6.4 server. Things seem to work OK. I personally only really use InnoDB tables for my databases, but only the standard 'mysql' table is in MyISAM format. I ...
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2answers
30 views

What's the best way to translate a website

I have a website in Django using MySQL, and I have more than 4.000 entries that I want to translate. What's the best way to do it? Create a new database for every language? Create other table for ...
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1answer
22 views

Impact of replication compression & encryption on performance, traffic?

What is the impact of MySQL compressed-slave-protocol on replication traffic? According to High performance MySQL it can lower the traffic to a third of the same replication without the compression. ...
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MariaDB Galera setup with drastically different amounts of memory used on cluster nodes - why?

We have a 3 node MariaDB Galera cluster. All nodes are identical and the config on each is identical. They have 64GB of RAM each. The output of the following query is 28: SELECT ...
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2answers
32 views

Fastest way to create local copy of live InnoDB MySQL database?

We have a MySQL database (InnoDB) on our live Ubuntu 12.04 server which has grown quite large (25gb+). Every month or so we need to copy this database to our development machines to work on locally. ...
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1answer
248 views

Strange Locking issues while playing back logs via percona playback

Problem while replaying logs I am in the process of benchmarking a new DB node (specs at the end) and have run across some strange behavior: As described here i: Created a dump (innobackupex ftw) ...
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7 views

How to link a MySQL Table with a binary key into Access?

In MS Access I've created a linked table via ODBC to a MySQL table with a binary(16) primary key column (UUID). MS Access only shows the first row, all other rows have #deleted entries. I guess the ...
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Securing Your MySQL Server within your team?

Recently I have been having an issue with our internal team members changing the password of the root user. I noticed the following things: OLD_PASSWORD = 1 (So all passwords on our development ...
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+50

Replication from EC2 Master to RDS Slave - Connecting to master

I am migrating my company's database from an EC2 instance to an RDS instance. I have already migrated a snapshot of data and am now trying to set up replication to get the data that has been added ...
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22 views

How to use Select query just right after Insert on master in a query.?

I have a question on mysql replication. As usual, I deployed my db structure like the Update on master db, the select on slave. My questions. If I use SELECT query just right after INSERT in a query, ...
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1answer
94 views

How to recover from two queries stuck in kill state causing all the database to not respond?

During a INSERT INTO new_table (f1, f2, ..., fn) (SELECT f1, f2, ..., fn FROM table) I clicked the new_table in php-myadmin which ran a simple SELECT * FROM new_table LIMIT 0, 30 which ofcourse ...
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1answer
34 views

MySQL silly query plan

I'm using 5.6.15-56-log Percona Server. Here's my table(which has over 5M records) CREATE TABLE `promotion_codes` ( `id` int(11) NOT NULL AUTO_INCREMENT, `code` varchar(255) DEFAULT NULL, ...
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1answer
40 views

Formatting a float value

I am fetching data from MySQL using PHP. I know that most values stored in the database are float. Sometimes, the database outputs values like 3.9999E-5 and sometimes like 0.00104961904762 (14 ...
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1answer
289 views

multiple line text values in mysqldump text export file

I'm trying to export +100mil record table into txt file. My plan is split up txt file to small pieces by size or line then import. I have one text field has multiple line like blog post text, in txt ...
2
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1answer
107 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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1answer
106 views

MySQL replication using a lot of IO

I'm having big troubles on a database pool I've setup recently. There is a master, and 4 slaves replicating one DB. All using MyISAM engine. Thing is, during the replication period (when the slave ...
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2answers
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MySQL Slave not updated

This might be a duplicate of questions on the same problem asked before. But all the suggestions to the previous questions do not seem to work in my case. I have set up Replication using SSH Tunnel. ...
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1answer
65 views

Get child record from specific root

I have two tables articles and topics and I am using MySQL 5.6 Articles id topic(fk on Topics.id) featured 1 1 1 2 2 0 3 3 ...
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1answer
105 views

Avoiding Multiple Queries when Searching for Records Associated with a Set of Records

So, I am sure I have done something really stupid while designing this, and I'm open to schema changes if they'll really help me out. On to the problem: I have a custom shopping cart system (backed ...