InnoDB : MySQL's ACID-compliant Storage Engine

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1K unused pages in each InnoDB buffer pool instance

I have configured a InnoDB buffer pool of 12 Gb, split into a dozen instances 1 Gb each. The buffer pool hit rate is 1000 / 1000, therefore so far it's looking good. Looking at the stats of the ...
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Completely reset innodb logs and files

So long story short, we've been dealing with a corrupt innodb installation on a MariaDB 10.0 server after a power outage, specifically a log in the future error. Rather than try and fake the log ...
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14 views

Monitor locks over long period of time

I am having some issues with one of my tables in a production server. I know there are many diffrent threads running on this table. I need to put some kind of monitoring tool to see how many locks ...
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How to use RESTRICT for Foreign Key in mysql?

In the database structure of CREATE TABLE Country ( name varchar(40) NOT NULL, PRIMARY KEY (name) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; CREATE TABLE City ( name varchar(40) NOT NULL, ...
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MySQL Index creation failing on table is full

UPDATE: tl;dr: The problem was MySQL uses the TMPDIR when creating indexes. And my TMPDIR was the one running out of disk space. Original Q: I'm trying to add an index to an InnoDB table, and ...
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60 views

Query with Indexes slower than without Indexes

I'm using MySQL 5.6 and my storage engine is InnoDB. I have a table with 1 million rows containing with the columns: ID (primary key) FirstName LastName foreign_key_id (foreign key, NOT NULL) ...
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173 views

Sudden MySQL freeze, with spike in dirty pages, but without obvious write queries

I'm systematically (1/2 times per day) experiencing a freeze in the DB server. Suddenly, all the COMMITs get stuck in 'init' state; they pile up (up to 20/30), an almost no other queries are executed ...
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104 views

Restore InnoDB from .frm files

My database crashed and my PC and I now only have the .frm and .ibd files left. Is there any way to restore my database?
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Making sense of INNODB buffer pool stats

After having read this page in the mysql documentation, I tried to make sense of our current InnoDB usage. Currently, we allocate 6GB of RAM for the buffer pool. Our database size is about the same. ...
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357 views

Is it a waste to set innodb_buffer_pool_instances greater than the # of CPUs?

I set the innodb_buffer_pool_size to 20GB on a server with 12 CPU cores. My full database is 11gb, however most of it is archived tables that are almost never used. The total queried data is around 3 ...
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195 views

Best configuration for MySQL? InnoDB and MyISAM

I read that InnoDB is supposed to be better at writing into MySQL than MyISAM, however, I'm trying it out, by running 3000 MySQL queries(Inserting rows, 8 Columns + id)... but results haven't turned ...
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Why does InnoDB store all databases in one file?

It was convenient that MyISAM used to store each table in a corresponding file. InnoDB has made advancements in many aspects, but I wonder why InnoDB stores all databases in one file (ibdata1 by ...
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1k views

Restore InnoDB to different machine

It was pointed to me from serverfault that the following question would be a better fit here so this is basically my original question from there. I currently have backups that were taken with ...
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InnoDB: why “non-locking” SELECT still gets locked?

This issue can be related to my first question: InnoDB: very slow random updates, hanging in “updating” state But i think it needs to be clarified in a separate thread. The Problem: a simple read ...
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1answer
59 views

Is the SQL syntax for InnoDB gauranteed to be the same between MySQL, MariaDB and Percona?

I develop an application that uses MySQL and explicitly uses InnoDB table engine. In a few cases we have clients using this application with MariaDB or Percona. I understand that MariaDB and Percona ...
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126 views

How does InnoDB access disk?

I know that block(multiple disk sectors) is the basic unit of data transfer for the virtual file system so, if NTFS uses 4 KB cluster size for files how does InnoDB access disk if it uses 8 KB page ...
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1answer
1k views

using Aria vs InnoDB vs MyISAM

I was wondering (if anyone knows) if Aria database is crash safe . I had some tables with MyISAM which were getting corrupted very often and switch them to InnoDB . However innodb is a bit slower and ...
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199 views

Too much IO to MySQL InnoDB log files

I am using MySQL version: 5.5.38 I have dedicated HDD to InnoDB log files using innodb-log-group-home-dir option. atopsar -d 30 shows big load (>50%) to this HDD The thing is that I have only 75 ...
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MySQL queries waiting for other queries to finish

We have 30-40 different projects in Python and PHP that update, insert and select more than 1 million rows of data in MySQL DB every day. Currently we use InnoDB Engine for our tables. The problem: ...
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InnoDB: very slow random updates, hanging in “updating” state

I've been fighting my problem for the whole last week, studying stackexchange threads with similar issues in the first place. The main problem is that after switching from MyISAM to InnoDB ...
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1answer
63 views

MySQL - NOT IN … vs LEFT JOIN

I am trying to understand in terms of performance which approach is better: Query 1: SELECT * FROM table1 WHERE col1 NOT IN(SELECT col1 FROM table2) Query 2: SELECT * FROM table1 LEFT JOIN table2 ...
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53 views

MySQL INSERT … SELECT Performance

I know that this query will lock table2: UPDATE table1... SELECT .. FROM table2 How about this query ? INSERT INTO table1... SELECT .. FROM table2 Does this query also create a lock on table2?
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112 views

Missing statement information from 'LATEST DETECTED DEADLOCK' InnoDB status output

I'm learning how to interpret the LATEST DETECTED DEADLOCK section in the output of SHOW ENGINE INNODB STATUS, and had a question about the output. Some sample output of SHOW ENGINE INNODB STATUS ...
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21 views

How can I disable xb_doublewrite?

Getting error while service restart. [ERROR] InnoDB: A parallel doublewrite file /test/mysql/xb_doublewrite found on startup.
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What does having the primary key as the last column in a composite secondary index in an InnoDB table do?

Say I have a 1-to-N relationship (person_id, pet_id). I have a table where pet_id is the primary key. I understand that an InnoDB secondary index is essentially a B-tree where the values are the ...
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41 views

Migrate from innodb_file_per_table to off in MySQL ALTER TABLE removing ibd files

Trying to migrate individual tablespaces back into the shared ibdata tablespace. MariaDB version 10.0.16 SET innodb_file_per_table to off in MySQL, restated mysql and new tables are in fact going ...
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388 views

Migrate from innodb_file_per_table to off in MySQL

We have a large number (2,500+) of databases and users in MySQL 5.6 on a single virtualized server (4 cpus and 8GB of memory). All the tables are using InnoDB. The actual data size is not very large ...
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41 views

MySQL InnoDB constraint does not work

I stumble upon strange behavior with innoDB constraint, and cannot find cause of it. I have tables with data. Below listed their structures: CREATE TABLE `contents` ( `id` int(10) unsigned NOT ...
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55 views

How I can reduce disk IO in MySQL 5.6.26?

I was using MySQL version 5.1.52 for my application but recently I have updated it to 5.6.26, but now I am facing very high disk IO. Following are system configuration: OS : Linux 2.6.39.4 RAM : ...
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8 views

Server memory consumption not changed after innodb buffer size change

I observed a strange thing while applying the innodb_buffer_pool_size on mysql. I applied the innodb_buffer_pool_size=20G (75% of my physical RAM size) and as per logs and innodb status the mysql is ...
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38 views

How to delete rows from the mid of the table without any where condition?

I have a table testing with two columns id: auto_increment name: varchar(20) I fired a query select * from testing limit 1, 2 which gave me 2nd and 3rd record. Now, I want to delete these records ...
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22 views

In [Percona] MySQL, is the Adaptive Hash Index included in the Total memory allocated count?

I'm debugging a memory problem with MySQL 5.6 (I'm using the Percona distribution), but I can't figure out, searching around the web, if the Adaptive Hash Index amount is part of the Total memory ...
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Better understand table indexing best practices

I'm not completely sure when would I start indexing my tables, when there are some criterias that I should consider: The tables are not that big, I think (1000 - 10,000 rows). The searches are made ...
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1answer
25 views

Partition Wise Joins in Mysql

Is it possible to create or simulate a partition-wise join in Mysql/Innodb?? Here is a good description of partition-wise joins.... ...
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35 views

InnoDB file per tablespace

I am using following syntax to create an InnoDB table: create table InnoDB_Test(a INT) DATA DIRECTORY='/var/log/storage/MySQL' INDEX DIRECTORY='/var/log/storage/MySQL' engine=InnoDB;` I want to ...
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260 views

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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51 views

Very Very Veeery slow insert queries

I am writing here because I`ve already spent days reading tutorials, other topics in here, and trying different configurations. The project : Fashion website with ~200k products which should be ...
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1answer
56 views

MySQL - Deleting old data; Select with index taking time

I am a bit confused about 2 queries. First query I am running on a 50m rows table by index on a timestamp row with a limit, I would expect the query to be immediate regardless of the size of the ...
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2answers
55 views

Memory leak on MySQL slave?

I have a Percona MySQL master-slave server configuration(5.6.20-68.0). The memory usage by MySQL on the slave server is constantly growing. Now it reached 68G despite on fact that ...
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1answer
95 views

ERROR 1031 (HY000) at line X: Table storage engine for 'TBL' doesn't have this option

I am trying to import mysqldump into following system: # cat /etc/redhat-release CentOS Linux release 7.2.1511 (Core) # rpm -qa | grep ^mysql mysql-community-libs-compat-5.7.11-1.el7.x86_64 ...
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Boosting select queries during INSERT ON DUPLICATE KEY UPDATE into 150Gb innoDb table

I have a single server with 2 innoDb tables: 35Gb (partitioned, 24M rows), 150Gb (without partitioning, 220M rows). 25% data, 75% index. 99% of select queries are SUM + WHERE + GROUP BY. 100% of ...
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1answer
109 views

Query about MySQL Semaphores in Engine Status

During a recent problem / slow down with one of our slave databases I noticed that when I ran SHOW ENGINE INNODB STATUS. I am getting the following: ---------- SEMAPHORES ---------- OS WAIT ARRAY ...
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40 views

Cannot open InnoDB table though the .frm file for the table exists

tonight, my local Server has crashed because the power went out. I do not have backups because this was only experimental. And for the sake of learning, I'd like to know what to do in this case. ...
0
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2answers
56 views

MySQL -Query with Union doesnt use index

Long story short, the following query runs immediately: SELECT COUNT(*) FROM indicators.fileso WHERE sha256 IN ( SELECT a.sha256 FROM temp.ananifilesinfo a JOIN indicators.filesi fi ON ...
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92 views

InnoDB MVCC vs Locking

From what I understand you InnoDB supports Row Level Locking MVCC (Multiversion Concurrency Control) Row Level Locking Locking is for when multiple writers are trying to update the same ...
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31 views

MySQL on idle low-end server unresponsive

I have a small virtual Server: 2 Cores, 2 GB RAM, Windows Server 2012 R2, Plesk, MySQL 5.6 (my.ini see below). Pagefile is disabled. Taskmanager says 1,3 GB RAM used. Only a single Wordpress ...
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113 views

Consistent backup of large DB --single-transaction

I need to mysqldump a large DB (330 GB) in order to set up a slave for replication. Does --single-transaction allow me to dump the entire DB without shutting mysql down and keeping it down for the ...
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MySQL Replication issues on server placed in different continents

I am running 2 cpanel servers with MySQL Replication set on them, one in france the other in US. Running a database hungary site. Replication was setup to load balance as well as for failover reason ...
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2k views

Are many NULL columns harmful in mysql InnoDB?

As I explored the clustered B-tree index system of InnoDB, I think that the presence of many NULL (or small) columns has no significant effect on InnoDB performance. Does the presence of excess ...
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1answer
20 views

Mysql locking - How to acquire a lock in the DB for each userId

Hi I have a J2EE Server(clustered) that executes requests from multiple users. I would like that each request of a given user will be handled like so: { acquireLockForUser(userId); // i.e. insert ...