InnoDB : MySQL's ACID-compliant Storage Engine

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3
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1answer
2k views

MySQL: Lock wait timeout exceeded

I have a developer that has been trying to alter a large table (~60M rows). Via LiquidBase/JDBC they're running ALTER TABLE foo DROP FOREIGN KEY fk_foo_1; Today while it was running I checked in ...
3
votes
1answer
53 views

Row size error with MySQL

I'm running a MySQL server on my Macbook (for testing). Version is 5.6.20 from Homebrew. I started running into "Row size too large" errors, and I've been able to reduce it down to this test case. ...
8
votes
2answers
187 views

Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
1
vote
1answer
22 views

Table is dropped but ibd file still exists

I was dropping some unwanted tables I have in the MySQL. When I run a drop table, its showing table doesnot exists. But when a check in the data directory, the .ibd file exists and its almost 1GB. How ...
2
votes
1answer
80 views
+50

MySQL RDS Instance eating up memory and swapping

I have an issue with memory on a RDS instance which is of db.m2.4xlarge class. Below are the specifications of the RDS instance Instance Class: db.m2.4xlarge ( 68.4 GB of RAM ) Engine: ...
1
vote
1answer
22 views

InnoDB deadlock with INSERT .. SELECT

I am trying to understand why a deadlock occurs when two workers in parallel are running INSERT .. SELECT queries on a table which has both 1) auto incremented primary key, 2) a unique index on ...
2
votes
1answer
99 views

poor and/or unreliable InnoDB performance

I recognize that there are a ton of posts like this, but after reading up on InnoDB performance problems, nothing I tried has helped. I have a database containing four InnoDB tables. The largest ...
2
votes
1answer
27 views

Innodb DB Consuming IO even when no operations are being done

I am currently doing some stress testing where I am pushing inserts to the database as fast as I can. The simulation inserts 10000 records per second. After inserting around 200 million records I ...
0
votes
2answers
2k views

MySQL 5.5 Fail start Fedora 16

I installed mysql and mysql-server from the repos (MySQL version 5.5). Then tried to start it, but got an error. [root@server]# service mysqld start Redirecting to /bin/systemctl start ...
1
vote
1answer
22 views

MySQL Delete Rows from Slave

I want to truncate the majority of data on a slave such that it only has the most recent records. I'll eventually demote the current master, making it a read-only archive, and promote the truncated ...
6
votes
3answers
30k views

MySQL: how to restore table stored in a .frm and a .ibd file?

I have previously saved a copy of /var/lib/mysql/ddms directory ("ddms" is the schema name). Now I installed a new MySQL on a freshly installed Ubuntu 10.04.3 LTS by running apt-get install ...
0
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0answers
19 views

MySQL DATE vs DATETIME read/write performace

Did anyone perform accurate read/write performance comparisons of MySQL's DATE vs DATETIME column types? Please do not bother writing "It should be faster" or "I think it's faster". I am looking for ...
0
votes
1answer
93 views

Need help to understand how information_schema.TABLES get updated

I created large innodb table mysql> select count(*) from big_data; +----------+ | count(*) | +----------+ | 23822336 | +----------+ checked the stats in informaion_schema.TABLES mysql> ...
6
votes
4answers
6k views

Cannot open table mysql/innodb_index_stats

After a fresh install of XAMPP and import from my linux live db that is working to the windows Dev-stage, I started encountering problems with INSERT. Everything else seems to work well. The errors I ...
2
votes
2answers
36 views

Copying datadir directory enough for backing up a database with InnoDB tables?

I have an innodb table with 80 million rows and it's extremely slow with mysqldump so I'm thinking of copying the datadir directory for a backup / transfer. I used to copy database with only MyISAM ...
1
vote
2answers
42 views

Difference between On Delete Cascade & On Update Cascade in mysql

I have two tables in MySQL database- parent, child. I'm trying to add foreign key references to my child table based on the parent table. Is there any significant difference between ON UPDATE CASCADE ...
1
vote
1answer
36 views

Revoke write privileges vs setting database to readonly

I am planning to do a database migration to a new server. During the transition stage, I do not want Apache user to be able to write anything to the database. I have two options. Revoke write ...
3
votes
4answers
113 views

How do I prove that the act of removing foreign keys doesn't corrupt existing data?

TL;DR: Prove that in practice, the execution of the alter table table_name drop foreign key constraint_name statement does not corrupt existing data. The important consideration is the execution of ...
1
vote
2answers
475 views

Which one to use? InnoDB Replication or MySQL Cluster?

I am building a url shortener and I use InnoDB as the storage engine for link data. I will start with a single VPS containing both application instance and MySQL database instance on the same Virtual ...
2
votes
1answer
37 views

Why is there no data loss with mysql innodb_flush_log_at_trx_commit set to 0?

Here is the MySQL info: mysql> show variables like 'innodb%flush%log%'; +--------------------------------+-------+ | Variable_name | Value | ...
3
votes
2answers
760 views

How much data is needed to show MySQL Cluster's performance scaling vs. InnoDB

I am evaluating MySQL Cluster as a possible replacement for an InnoDB schema. So far, I have tested it with 10s of MB of data, and found MySQL Cluster slower than InnoDB; however, I have been told ...
0
votes
0answers
9 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
0
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1answer
27 views

select where index + other field

Learning indexing I have made an index, consisting of usergroupid and birthdate I understand that queries will then benefit from indexing when searching usergroupid and/or birthdate But what ...
0
votes
1answer
1k views

What is the actual difference between innodb_autoinc_lock_mode 0,1,2

I would like to understand the differences between innodb_autoinc_lock_mode options 0,1 and 2 when parallel load data infiles are given. I see in "0" option, it locks the entire table and does the ...
0
votes
2answers
908 views

InnoDB Tablespace critical error in great need of a fix

Link to screenshot : http://www.nouvellesduquartier.com/i/1/p/Munin_%20Critical_MySql_InnoDB_.JPG (The value reported is outside the allowed range - Byte free, free, gauge, warn, critic) Question: ...
3
votes
1answer
497 views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: ...
2
votes
3answers
197 views

MySQL buffer pool usage + high load

We've got a quite powerful server: HP ProLiant DL360p Gen8, 2xIntel Xeon E5-2630 2.30GHz, 128GB of RAM. The whole data set should fit in memory: mysql> SELECT ...
1
vote
2answers
839 views

Why would increase in innodb_buffer_pool_size slow down MySQL?

5.1.68-cll - MySQL Community Server on CentOS The system has 32GB of RAM. I increased innodb_buffer_pool_size from 10240M to 15360M (10GB -> 15GB). Time taken for a series of identical operations ...
3
votes
2answers
227 views

MySQL runs out of memory when importing innodb database

I have a small VPS with 512MB RAM and no swap (can't have any). I am importing a 1.5GB innodb database with mysql -u -p < database.sql Before the operation can finish it says : Lost connection ...
0
votes
1answer
197 views

MySQL select by primary key against 100M of records within 30ms

I have no expirience with MySQL and database performance tuning in general. Wondering whether it is possible to perform a large number of selects against 100 millions of records by primary key within ...
0
votes
1answer
122 views

innodb completely crashed after interruption

I am having a major crash on mysql affecting a lot of websites. We had a crash on our SAN storage. Since that time, mysql refuse to start. I tried to reinstall mysql, but still no luck. I think ...
2
votes
1answer
34 views

MariaDB ALTER TABLE produced a separate .ibd file, how can I re-integrate the data into the shared table space?

We have a multi-GB InnoDB MariaDB (recently switched from MySQL). For some reason, the value of innodb_file_per_table changed to ON (we wanted only one innodb data file explicitely). So when I ran an ...
1
vote
1answer
27 views

MySQL: Merge Same Database on Several Location into Single Location

I have registration form, which exactly same for several location. Each of them has REG column, which this field is unique for each row. Basically each data input have different REG number for it, ...
1
vote
1answer
139 views

Innodb buffer pool indexes versus data usage

The server has 128GB of RAM. The innodb_buffer_pool_size is set to 106GB. mysql> show global variables like 'innodb_buffer_pool_size'; +-------------------------+--------------+ | Variable_name ...
0
votes
1answer
291 views

The total number of locks exceeds the lock table size, even after increasing buffer pool size

I am trying to partition a table with 200 million records in it. This table already exists: CREATE TABLE linkmap_ntoken ( target_nToken varchar(200) NOT NULL, ntoken_hashcode int(15) NOT NULL, ...
0
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1answer
49 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?
2
votes
1answer
46 views

Wordpress blog where pages are almost-always served from cache: SSD or more RAM?

I am working on the design of a Wordpress blog which when finished will almost-always serve pages from disk cache and this is because all posts will be published in batch and then cached, with at ...
0
votes
1answer
25 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 ...
0
votes
2answers
18 views

Restoring data from dumped sql file gives: mysql: unknown option '--innodb_file_per_table

I was trying to separate DB indexes from ibdata1 I took the steps in what-is-the-best-way-to-reduce-the-size-of-ibdata-in-mysql I dumped data, dropped databases, and started mysql service. I got the ...
0
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0answers
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 ...
1
vote
1answer
829 views

MySQL SELECT query hangs - Opening Tables INNODB

On my server I have 6 MySQL databases. They all power Wordpress websites. For some reason, 2 of these databases are not accessible. To my knowledge they use INNODB, but I can't confirm it as even ...
0
votes
0answers
27 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 ...
0
votes
1answer
26 views

Is it possible to restore a database snapshot from a 64 bit system to a 32 bit one?

I would like to perform a restoration test on a snapshot backup of my MariaDB database using a test server running on a 32-bit OS. My production server is a 64-bit system. I would like to know if the ...
0
votes
1answer
98 views

InnoDB Failure of some kind

I have MySQL 5.5 installed. I tried to install Joolma but it failed. I went into their sql and replace EGNINE=InnoDB with MyISAM and the install worked. InnoDB is listed under SHOW ENGINES; Any idea ...
1
vote
2answers
659 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 ...
0
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1answer
67 views

MySQL - Indexes deleted, reduced column size but table size increases

Here is the original table definition which contains 107547934 (~107.5M) rows CREATE TABLE `twitter_tweets` ( `id_str` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL ...
3
votes
2answers
1k views

MySQL information_schema doesn't update

I have a database, say abc, in mysql server. It has only one table named test. test uses innodb engine and I've set innodb_file_per_table to true. After I run the query delete from abc.test, I want ...
1
vote
1answer
34 views

MySQL consistent nonlocking reads vs. INSERT … SELECT

So, from my reading of the MySQL 5.5 documentation and some experiments I did with colleagues, I understand that the following is the case: With InnoDB tables, a simple SELECT statement (one that ...
0
votes
0answers
60 views

Finding the right MariaDB configuration

I’ve read several articles about how to configure MySQL/MariaDB, but now I’m kind of confused how to find the right values. Some articles suggest not choosing to high values, others recommend adapting ...
0
votes
1answer
47 views

How to start mysqld with read-only data directory?

I'm trying to start MariaDB in a docker container, using a data directory from the host mounted read-only. MySQLd is of course shut down on the host. Unfortunately, even with adding the read_only flag ...