InnoDB : MySQL's ACID-compliant Storage Engine

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Why does mysql make delete offset?

I am implementing database(College project).So I come across innodb diagrams in github ...
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906 views

MySQL 5.7 InnoDB is extremely slow on spatial data compared to MySQL 5.6

I have a table area which contains ~300,000 rows. It is defined as follows: CREATE TABLE `area` ( `area_id` bigint(20) NOT NULL AUTO_INCREMENT, `boundary` geometry NOT NULL, `name` varchar(255) ...
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Our app lags “randomly” due to Disk I/O spikes?

Our database (InnobDb) is spiking at 99% I/O at random times. After the spike it goes down to about 2% until it spikes agian. There aren't any spesefic, huge queries running in these intervals that ...
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Optimizing a group by/where in/min() query in MySQL

Assume I have a table that looks like such (The actual column names of my real table would only make things harder to explain, so I have created a mimic that behaves similarly). id | cond1 | cond2 ...
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Trick for AUTO_INCREMENT on composite keys in InnoDB

In contrast to the MySQL MyISAM-Engine, the InnoDB-Engine can not handle when one column of a composite primary key is declared as AUTO_INCREMENT. For example consider the following table: CREATE ...
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52 views

Mysql only using 10% of cache [duplicate]

I have a dedicated Mysql server that only uses 1.1 GB out of 16 GB ram (picture link 1). I belive this leads to my Disk I/O utilization beeing at 75% peaks (picture link1). How can i configure sql ...
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1answer
2k views

MySQL InnoDB page_cleaner settings might not be optimal

Seeing this note in mysqld.log: [Note] InnoDB: page_cleaner: 1000ms intended loop took 15888ms. The settings might not be optimal. (flushed=200 and evicted=0, during the time.) There seems to be ...
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1answer
45 views

MySQL: Point in Time query using InnoDB log sequence number?

Is it possible to do a point in time query based on a log sequence number? For example, I would like to do something similar to Oracle's "as of" query select foo from bar as of scn 123923455; ...
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766 views

Mysql (percona-server 5.5) completely stalls during import (myloader)

While configuring our new servers (IBM X3650M4, 2x Intel Xeon E5-2620, 64G RAM, RAID 10 (4x 240G SSD)) we bumped into a strange problem. We're trying to import dumps (mydumper) from our (old) ...
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slow query on mysql innodb table with 2 million rows

I have a table with about 2 million rows (growing at about 1 million every 3 months) and am having trouble with slow queries. I've tried changing my query and indexes (ensuring left most order) to no ...
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153 views

Corrupt InnoDB: Start mysqld only innodb_force_recovery=6

I am working with version 10.0.19-MariaDB-1~trusty-log and I'm only able to restart mysqld with innodb_force_recovery=6 and I don't know why. The output of the /usr/sbin/mysqld is the following: ...
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367 views

Mysql Tuning for a small server

I have a small Cloud Server running under Ubuntu 2 core, 2GB ram and 2GB swap, with Plesk Panel, Apache, Nginx as reverse proxy and Mysql 5.5. I have about 18 domains hosted here and each domain has ...
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59 views

Optimizing slow query

For a few days now, i'm trying to optimize this query. But still I haven't found the right solution in how to fix this. The contents table contains about 20 million records. As the connect table ...
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95 views

MySQL: equivalent of Oracle's SCN and “as of” queries?

Does MySQL have a similar concept to Oracle "SCN" (system change number)? Is there an equivalent way to do "as of" queries? e.g. select foo from bar as of SCN 104086584;
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MySQL InnoDB Error [duplicate]

I'm currently experiencing issues with my server MySQL databases as I keep receiving the following error: InnoDB: The log sequence in ibdata files is higher InnoDB: than the log sequence number in ...
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1answer
651 views

What does “cleaning up” mean in MySQL InnoDB transaction status and how to prevent it?

In our database (MySQL 5.6.22 on RDS) we have a lot of transactions (~500) in a state "cleaning up" under the load: > SHOW ENGINE innodb STATUS; ... ------------ TRANSACTIONS ------------ ... ...
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mysql innodb db full text search FTS_DOC_ID column

I am adding full text search to already existing mysql tables that have primary auto incrementing key of id integer. When I add the full text index I get a warning: /*!50604 ALTER TABLE ...
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41 views

Is it safe to run parallel innodb single-transaction of individual tables

I can't seem to find the internals for --single-transaction mysqldump option for InnoDB tables, but is it possible to use --single-transaction for single tables in a parallel dump so that the ...
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2answers
122 views

DB randomly locks up when innodb_buffer_pool_size is set high

I have been struggling to work out what could be happening here but for many months, since upgrading to mysql 5.6 we seem to be experiencing random lag spikes in page loads which has been tracked back ...
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1answer
93 views

Mysql is shutting down in every 5 minutes

My MySQL 5.6 is shutting down about in every 3-5 minutes. I only can use it after restart. I don't know what happened; everything was OK 2 days ago. What do you suggest to me? Here is my ERR file ...
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1answer
665 views

mariadb won't start (InnoDB error: space header page consists of zero bytes in data file ./ibdata1)

The following messages are in /var/log/mariadb/mariadb.log when I try to start mariadb: 151103 13:42:01 [Note] InnoDB: Initializing buffer pool, size = 128.0M 151103 13:42:01 [Note] InnoDB: Completed ...
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Does MySQL Workbench lock database during migration process?

I am doing a migration of my database from one server (RDS) to another (localhost) via the MySQL workbench tool. I want to know if during this process my database will be locked for write and read ...
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3answers
141 views

UPDATE query periodically is slower by factor of 5000x

I run a site (Magento) which have a problem with a specific UPDATE query. Under heavy load, this query runs ~200 times/minute, and takes in average 1 ms (stdev 0.2 ms). However, at intervals of 1-2 ...
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1answer
125 views

Is it ok to have 'view count' column in the same table?

Let's say I have a website similar to YouTube where I'm storing and displaying the 'view counts' for each video. It is ok if I'm storing the view count column in the same table as the actual view ...
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What would cause database CPU load to increase 5x+ during peak hours, when traffic only doubles?

I'll start with a screenshot of CPU load on my database server for the past three days. http://i.imgur.com/sSZJdCb.jpg As you can see, it spikes from 20% to 100% load every day (would be even higher ...
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73 views

Memory usage still growing

I have problem with my production mysql server. The memory usage is still growing and I don't know why. Trouble started when we changed the server. My mysql version: 5.5.44-0+deb8u1-log - (Debian). ...
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14 views

Memcached innodb plugin load testing

I am testing with memcached innodb plugin for MYSQL and so far I have been able to create containers and insert data. This works well for me. I only have one issue and that is to load test/stress ...
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1answer
56 views

Why does STRAIGHT_JOIN consume more CPU?

Why does STRAIGHT_JOIN consume more CPU than a regular JOIN? Do you have any idea? When I use STRAIGHT_JOIN on one of my queries, it speeds up the query like from 12 seconds to 3 seconds. However, ...
2
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1answer
127 views

autoincrement column issue in MYSQL

We are using an autoincrement column in a temporary table, and doing multiple time inserts. The autogenerated ids are not being generated consecutive (I have attached a sample simple query: 16 is ...
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3answers
224 views

Performance impact of NOT using a foreign key (many dedicated 1:many key-key tables vs non-fk generic key-key table)

We're using a lot of association tables to manage 1:many relationships among a variety of different objects in our system. To illustrate the question, two examples would be: users, events, ...
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MySQL database hangs but less CPU

I create an application for 30 concurrent users using C# and InnoDB of MySQL (mysql-5.1.35). The size of database is more than 100M lines (~20GB). Most of data is come from 7 active table (2M ...
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MySQL Command to Mass Change Specific DB from MyISAM to InnoDB and vice versa?

I have an mu WordPress database and I want to change it from MyISAM to InnoDB to test its performance. Which MySQL command/commands will do it for all of the tables instead of doing manually one by ...
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326 views

MySQL - Slow InnoDB Write Speeds on Windows 10

I have Windows 10 bootcamped. I've installed the latest version of MySQL community server. I've also installed WordPress onto IIS. The MacBook has 16Gb of memory. Here is my config file [client] ...
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How to determine the best index on a table with 3 nullable columns?

I am examining a users table similar to this: CREATE TABLE `users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(50) DEFAULT NULL, `email` varchar(255) DEFAULT NULL, `password` ...
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Columnar & Row Oriented DB

In a previous question, I discussed some challenges with a row-oriented table. I have two tables in this application. The first table is well-suited for row-oriented operation; the second is ...
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Get Master Server Information from Slave instance

We need to get Master server information such as server IP and Port, we know this information is dumped into master.info file by default but what if it required within MySQL prompt as we are using ...
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1answer
94 views

How to stop Mysql ibd files from continuously growing

I have a mysql 5.5.44-0ubuntu0.14.04.1-log DB that has 2 tables that get a lot of data written to them then deleted within 48 hours, it is for a Salt system. The my.cnf is specifying ...
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1answer
95 views

LAST_INSERT_ID without AUTO_INCREMENT

I have following table, which does have an UUID as primary key, which also acts as foreign key. CREATE TABLE `xxx` ( `guid` char(36) NOT NULL, .... PRIMARY KEY (`guid`) ) ENGINE=InnoDB ...
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Find the last record of group of overlapped records

I have a little dilemma with filtering out result. The result and what I want to achieve is not very trivial and I didn't find an answer anywhere after extensive search. So here is my problem: I ...
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1answer
65 views

Does InnoDB store row counts in secondary index B-Tree non-leaf nodes?

Does InnoDB store row counts of child nodes in secondary index B-Tree non-leaf nodes? If so, does MySQL use this information to speed up COUNT(*) queries with range constraint (assuming appropriate ...
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1answer
264 views

MySQL Write performance bottleneck

We are trying to diagnose a MySQL Bottleneck, specifically for data writes. Basically, we have a single process that picks files from a folder and load into a MySQL table X using LOAD DATA CONCURRENT ...
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2answers
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Moving an ibd file temporarily to free up disk space

I want to optimize an InnoDB table but I do not have enough disk space. I have enabled innodb_file_per_table, so each table has *.ibd for each of their partitions. For example: 512MB ...
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1answer
34 views

MySQL 100+ instances on one Windows server

Please don't ask why I need 100+ instances on one server because I cannot say; suffice to say that I'm not impressed. They will be very small databases and not definitely not under any great load ...
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2answers
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Automatically set timestamps for “create” and “modified”?

I have currently following SQL table: CREATE TABLE IF NOT EXISTS `xyz` ( `id` bigint(20) NOT NULL, `guid` char(36) NOT NULL, `ts_created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, ...
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How do flush innodb table, copy files, then unlock tables from Windows bat file?

I can successfully execute "FLUSH TABLES myTable FOR EXPORT;" in MySql Workbench. Then I can copy the cfg and ibd files I need, and then I can go back to workbench and run "UNLOCK TABLES" and all is ...
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MySQL InnoDB over a Raw Device in an Active/Passive topology

We have an Active/Passive topology where there are two x86 complexes with a shared raw storage, where only one of the nodes in a given moment has an access to the shared storage (AKA the active node). ...
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Replication of MySQL databases, but only some of the data

I need to set up a system to do basically a partial backup/replication of a couple of MySQL databases (actually Percona XtraDB 5.5, all tables are InnoDB). There are a few hundred tables in one of ...
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innodb_flush_log_at_trx_commit=1 and flush-to-disk reality

I use the default settings of MySQL 5.5 on various servers and I have the following table: create table test._perf ( name varchar(255) not null ) engine=InnoDB; I have an .sql script which ...
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Where does InnoDB store transaction data before committing it?

I've done some tests using READ_COMMITTED and READ_UNCOMMITTED at home, using the JDBC technology. I see that READ_UNCOMMITTED can actually read uncommitted data, e.g. data from some transaction not ...
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How does lock works when delete rows through secondary index in InnoDB?

step1: InnoDB Transaction Isolation Level Repeated Read. step2: Table schema CREATE TABLE `follows` ( `id` int(11) NOT NULL AUTO_INCREMENT, `followable_type` varchar(255) DEFAULT NULL, ...