All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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MySQL Server hitting 100% unexpectedly (Amazon AWS RDS)

We've been struggling with this issue for months. This week we upped our RDS instance to the highest performing instance and although the occurrences have reduced, we're still seeing our database ...
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0answers
92 views

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 ...
2
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0answers
216 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 ...
2
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0answers
1k views

MySQL re-install fails under Mountain Lion

I have problems to reinstall MySQL on Mac OS X after it was running on my system. I uninstalled it because the PreferencePane wasn't working as expected, using the procedure described here: ...
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0answers
1k views

Index usage for database server

How can i fix the Index usage on one of our database server? It says from our Nagios control panel that: Service: DB Index Usage Host: MySQL Cluster Address: ( our IP ) State: CRITICAL Additional ...
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0answers
1k 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 ...
2
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0answers
103 views

Can't connect to MySQL Cluster Storage (data) nodes

I've deployed a MySQL Cluster with a few nodes, and I want to access the storage nodes directly from another machine using NDBAPI. When I tried to connect from the same host it worked, but when I try ...
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10 views

pub/sub database schema

I am having a hard time creating a pub/sub database schema with stateful metrics. Saying it aloud it sounds easy enough: "There are many organizations that will subscribe to checklists that are ...
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17 views

Getting InnoDb internal Errors on every query run

I am having following errors in error.log at the run of each query due to which I am not able to use error.log properly. 2016-05-30 09:39:58 7f7c7e3cb700 InnoDB: Error: Column last_update in table ...
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28 views

Null instead '0000-00-00 00:00:00' in mysql 5.7

Before: mysql 5.6. One of the columns in the table is created as follows: `f_stamp` datetime NOT NULL DEFAULT '0000-00-00 00:00:00' When i view this field in mysql client or using DataGrip, this ...
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13 views

Add index to mysql table with ndbcluster engine

I'm having trouble while adding index on mysql table with ndbcluster storage engine below is the error . [mysqlcluster ver. 7.4 GA] mysql> alter table `sks_staff_office` add index `pid_index` ...
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30 views

Converting a composite primary key to composite unique, and adding an auto-incremented PK column

Background I have taken over responsibility for a table that, in the long run, will grow monolithic. The table is a very simple link table with 2 columns, call them col1 and col2, both being foreign ...
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22 views

UTF8 Trouble while migrating from MSSQL to MySQL with MySQL Workbench

I am tasked with migrating part of our database from an on-site MSSQL server to an Amazon RDS MySQL. This will be my first attempt with a database migration, so I am doing a dry run from our MSSQL ...
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0answers
39 views

howto read/interpret “show engine innodb mutex” output?

We use a 3 node Galera cluster with version 5.5.41-MariaDB-wsrep MariaDB [(none)]> show engine innodb mutex; +--------+---------------------------------+------------------+ | Type | Name ...
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53 views

MySQL is using swap memory while I have plenty of free RAM

I have a 6 GB buffer pool size for my database; however, mysqld process is moving to swap while there is plenty of RAM available. I think pool size and pages along with pool of reads and pool of read ...
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46 views

MYSQL:[Note] InnoDB: page_cleaner: 1000ms intended loop took 4303ms. The settings might not be optimal. (flushed=396 and evicted=0, during the time.)

In MySQL5.7.11,the error log display the "[Note] InnoDB: page_cleaner: 1000ms intended loop took 4303ms. The settings might not be optimal. (flushed=396 and evicted=0, during the time.)" ...
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26 views

MySQL 5.1 - Display the error-message returned inside a stored precedure

I'm trying to find an alternative to display the error-message returned from MySQL-5.1/5.5 inside a stored procedure. The example below is what I'm looking for, however it's seems to be only allowed ...
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23 views

Can MyISAM tables affect the backup recovery of innodb tables on Amazon RDS?

I have an Amazon RDS instance containing several databases. All the tables are innnodb except from one, that is MyISAM and currently cannot be converted to innodb. I know that the recovery of MyISAM ...
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22 views

hosting mysql server on the cloud or local network pc

I have a question on whether to host a mysql server on the cloud or a local network pc. In the current work environment all users log on to the cloud and work from the cloud. All the work ...
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0answers
13 views

MariaDB strange user privileges issue

Server version: 5.5.47-MariaDB-log MariaDB Server / CentOS Linux 7 x86_64 I have two users: user@% and user@localhost with the same password but apparently different privileges (some privileges the ...
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29 views

MySQL/JDBC: Can a commit on server get missed on client?

I am wondering about when conducting a transaction of one or two updates/inserts from a JDBC client to MySQL Server over the network... In the event of losing the network during the commit, can I get ...
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15 views

Wildcard in CREATE grant in MySQL

MySQL allows the use of wildcards for database names, in order to allow an user to operate only on a subset of databases: GRANT ALL PRIVILEGES ON `foobar%`.* TO 'user'@'%' IDENTIFIED BY ...
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23 views

MySQL Error 111 caused by remote connection

This database has been running for years, such that all connections have came from the localhost address. Recently, I have been using xampp to develop new software, and have been connecting to the ...
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31 views

Access denied when trying to use Mysqlimport Utility (using Root Credentials)

We are trying to import large CSV files through Mysqlimport as described in This & This article. But even though I am using root credentials I keep getting the following error: mysqlimport: ...
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28 views

Groupwise max then join

I have a votes table that has many subitems. I have a subitems action table that records what action was performed by which user on which group, on which subitem, on which vote Users can either ...
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31 views

What is the maximum value for the index_length of a MySQL 5.5 table?

I'm trying to find out why a series of inserts is painfully slow (1 minute 15 seconds, on average) on a dedicated MySQL 5.5.47 server, while the same inserts are normally fast (less than 5 seconds) on ...
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34 views

Redis along with Mysql

I'm currently working on a mobile app alike Google Maps or Wave, but also including parking. The application its running with MySQL primarily. With at this stage most of our data is loaded by python ...
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64 views

mysql replication takes 6 seconds

I am struggling trying to understand why MySQL 5.7.11 semi-sync replication using RBR takes around 6 seconds between 2 VMs on the same physical host. I have verified the network bandwidth b/w the 2 ...
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0answers
40 views

How can I partition records vertically across machines?

I recently asked two questions: (1) how to store and connect partial records in two or more machines, with the record halves correctly associated, and (2) how to determine the increase in time/space ...
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0answers
25 views

MYSQL Created_tmp_disk_tables value increases on almost every query

Should I be concerned that tmp_disk_table # is growing even when I run a simple query like elect id from table with 1000 rows where id is an integer and is primary key) I've fiddled with other ...
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0answers
56 views

How can I migrate a WordPress site from MySQL to SQL Server Express?

I have developed a web portal in WordPress using xampp server. I have my database in MySQL. Now I need to deploy this WordPress portal on other system with SQL Server Express Edition. So how can I ...
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41 views

Missing DDL and table

I encounter the following errors after reinstalling MySQL Server. These seem to affect only one out of the several tables in the schema. The following errors are generated from MySQL Workbench. When ...
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38 views

MySQL Event scheduler not generating CSV

The scheduler seems to be running from INFORMATION_SCHEMA.EVENTS but there is no CSV output. The event scheduler has to automatically produce a csv to pass on the data to another system. It's like ...
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0answers
30 views

Using Galera-Replication, what's the use in having a GTID associated with your backup?

On the topic of using a backupscripts the documentation for galera-cluster states that: You can use backups of this kind to recover data, but they are insufficient for use in recovering nodes to ...
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0answers
44 views

Database has thousands of randomly named tables

Preface: First of all excuse me for bringing forwarding this weird question, as it could be just me. Situation: We have a Centos 6.5 Cloud VPS hosting our website, running MySQL 5.1 and it is also ...
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0answers
37 views

MySQL Slows Down after MYD file reaches 2GB (64 Bit OS)

MySQL seems to be writing rows OK (75,000 rows/min) until when the MYD file reaches 1.8 GB, and then the insert rate drops immensly (10,000 rows/min), and 1 hour later it's even slower (6k rows /min). ...
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0answers
37 views

use IFNULL in laravel

I have a query in laravel which is working fine. $subjects = $app->db->table('subjects')->LeftJoin('downloads', 'subjects.subjectID', '=', 'downloads.subject_id') ...
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0answers
92 views

Haproxy + Mysql Lost connection to MySQL server during query

I have setup a master-slave replication and added a haproxy before them. #HA-Proxy version 1.4.24 global log /dev/log local0 log /dev/log local1 notice chroot /var/lib/haproxy ...
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24 views

Trouble getting automysqlbackup to keep connection to MySQL server

I am trying to follow the instructions from the following page to set up backups for mysql. https://www.howtoforge.com/tutorial/mysql-incremental-backup-point-in-time-recovery/ However, once I get ...
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0answers
27 views

Visualize the effects of a cascading delete or update?

In MySQL, I'm working with a database that has integrity constraints on foreign keys (nothing overly special here). Is there a method to somehow visualize the effects of a cascading delete or update? ...
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0answers
26 views

When are UPDATE / INSERT operations processed in Online DDL in MySQL 5.6?

MySQL 5.6 includes functionality called Online DDL which allows ALTER operations to proceed on tables without applying a LOCK to the table (technically referred to as allowing Concurrent DML). ...
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328 views

Negative InnoDB Write Log efficiency in mysqltuner.pl results

I noticed something strange in results from mysqltuner.pl. I see this in mysqltuner output from three of my four servers with MariaDB 10.1.12: [OK] You have the latest version of ...
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27 views

MySQL master to slave dump fails when done over SSH pipe

When we need to [re]build a MySQL-5.5 slave, our usual approach is this (CHANGE MASTER TO / START SLAVE omitted for clarity): master$ mysqldump -uroot -p --all-databases --master-data > dump.sql ...
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0answers
19 views

Clustered index on last_update_at timestamp

I have a Votes table , which can be considered a wrapper. I have a sub_items table, which holds one votable item. One Vote has many sub_items. On sub_item is owned by only one Vote. I have a ...
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0answers
29 views

How to improve on this database design

I have different 'modules' . Currently , they are: Votes Chats To-do lists I am using mysql and long polling to get updates about these modules in near real time. I have also have a table called ...
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31 views

Joining and combining MySQL tables from Informix

I previously asked this in StackOverflow, But I couldn't find a solution, so I thought I'd share my problem here too. I have an old system that uses Informix for data storage, and I'm working on ...
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0answers
29 views

Manually specifying candidate masters in Maxscale

Looking over the documentation, I haven't quite been able to find if its possible to manually set the candidate master status of a server in Maxscale. The reason I am looking for this is because some ...
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0answers
63 views

Database design in MySQL workbench

After doing some change As Mr Vérace told me here in this question, by changing the id names of each table into table_name_id and using the singular notation, I still need your opinion about this ...
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0answers
32 views

how to edit kvp data as crosstab/pivot

I am keeping data in key/value pairs. I know how to convert that data into crosstab form using queries like this: <!-- language: lang-sql --> SELECT master.tag, MAX(CASE WHEN data.key = ...
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35 views

AWS RDS: Running db dumps in to the server really slow

I am migrating data from out servers to AWS (from MySQL to Aurora) and inesrting the data is terribly slow. Is there a way to speed things up? Right now I'm creating gzipped dump files on our server ...