InnoDB : MySQL's ACID-compliant Storage Engine

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Why does MySQL choose this execution plan?

I have two queries, select some_other_column from `table` order by primary_index_column asc limit 4000000, 10; and select some_other_column from `table` order by secondary_index_column asc ...
6
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2answers
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Is one-to-one relationship normalized?

Consider we have a large set of statistical data for a record; e.g. 20-30 INT columns. Is it better to keep the entire set in one table as they all belong to a record OR creating a another table ...
2
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1answer
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Sort buffers and tables on disk, MySQL/InnoDB

I have the following type of query frequently running: # Time: 120322 13:03:29 # User@Host: root[root] @ localhost [127.0.0.1] # Query_time: 17.039286 Lock_time: 0.000141 Rows_sent: 24 ...
3
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1answer
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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 ...
1
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1answer
2k views

How to recover the innodb when mysql data dir moved from one system to another system?

I have transfer the mysql data dir from one linux box to another box. When i start the mysql server. I can find that the innodb based DB are corrupted. So, may i know how to recover the corrupted ...
4
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2answers
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“freeing items” taking forever on inserts, updates and deletes

Recently I migrated all my MySQL database tables from MyISAM engine to InnoDB. I'm using the DotCloud MySQL service as my server (http://docs.dotcloud.com/services/mysql/). After the migration, ...
5
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2answers
10k views

Using multiple cores for single MySQL queries on Debian

I am running a MySQL server for tests on a VM (VMWare) with Debian as guest OS. The guest has four emulated CPU cores, so I set thread_concurrency to four. I am doing expensive joins on large tables, ...
0
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1answer
927 views

Problem with Error: InnoDB: page … log sequence … number is in the future!

i know this question was asked before, but i am at a point where i am really stuck and do not know how to continue with this problem and i would really like to know, what causes this error to come up. ...
1
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1answer
4k views

How to set a specific directory location for individual MySQL database?

Is it possible to set each database in MySQL to use a separate datadir? I'm running a userdir development (sandbox) server and would like to put the MySQL data files for the database(s) for that user ...
3
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1answer
143 views

What are some key configuration settings for using an InnoDb table for session storage?

I want to start clustering my PHP app servers but don't want to go for a sticky-sessions load balancing setup at this point. However, I want sessions that are persisted to disk and implement proper ...
5
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4answers
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MySQL subquery slows down drastically, but they work fine independently

Query 1: select distinct email from mybigtable where account_id=345 takes 0.1s Query 2: Select count(*) as total from mybigtable where account_id=123 and email IN (<include all from above ...
2
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1answer
996 views

ACID-compliance of MySQL master-master replication?

I've created two MySQL 5.1 servers, replicating off each other (log-bin) in a low latency environment (different AZs within an EC2 region). All tables that are being replicated are using the InnoDB ...
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3answers
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InnoDB table SELECT returns ERROR 2006 (HY000): MySQL server has gone away (after power outage)

This server is a virtual machine running CentOS 6.0, MySQL 5.5.21 There is a database named devSystem. There are InnoDB tables within. Running the following commands causes error ERROR 2006 ...
3
votes
1answer
4k views

How can I find who holds the lock based on the hex-dumped?

I've been reading the Diagnosing MySQL InnoDB Locks article. Karl E. Jørgensen writes on 2008 so I'm consfusing it is in effect. I would like to supply a snippet of the SHOW ENGINE INNODB STATUS: ...
2
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1answer
2k views

Why can't I get a lock on an InnoDB table?

I have problem with lock table command: LOCK TABLE v3_cam_date WRITE; the command always running with state: "Waiting for table metadata lock". Try to find out which thread was hold the lock on ...
10
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2answers
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innodb_file_format Barracuda

I have a couple questions for those more familiar. Most of my instances have been running Antelope despite having support for Barracuda. I was looking to play around with some compresses innodb ...
3
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1answer
1k views

Getting duplicate primary key for auto increment coloumn

I have a MySQL Innodb table with 'id' as auto increment primary key coloumn. My Scripts are doing following operations: insert ignore into tablename set x='a', y='b' update ignore tablename set ...
2
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2answers
7k views

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, ...
2
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1answer
719 views

Number of locks exceeded when adding foreign key constraint

I'm adding a foreign key constraint to table a (17mil rows) that references table b (15mil rows): >ALTER TABLE a ADD FOREIGN KEY (b_id) REFERENCES b (id); ERROR 1206: The total number of locks ...
1
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2answers
5k views

Innodb UPDATE performance

We recently switched one of our tables to innodb and now we are experiencing very slow UPDATE execution times. An update which used to take 0.010-0.030 seconds can now take over 70 seconds. Some ...
4
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1answer
1k views

Can SHOW TABLE STATUS query performance on MySQL be improved - Amazon RDS

I have a fairly large database on the Amazon Relational Database Service (RDS) running on MySQL 5.1.57. There are 900+ tables, so that running the "SHOW TABLE STATUS" query can take up to 30 seconds. ...
6
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1answer
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Tuning dedicated Percona Server with XtraDB for OLTP

Hardware specs for an OLTP DB dual quad core xeon with hyperthreading 24GB ram Hardware RAID10 BBU Software specs Standard install of Ubuntu 10.04LTS with default LVM partitioning Installed ...
2
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1answer
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MariaDB XtraDB Performance Tuning

I believe that innodb has a single read thread. However, with MariaDB you can set multiple read threads. I'm unsure what the recommended value would be. Questions Does anyone have any experience ...
6
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2answers
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Ibdata usage and Recommendations?

I have a Production server On November 5,2011 the ibdata size was 100G. In Approximate 3 months it is increased to 200G.So it has just doubled its size.So it is a Huge Data.Currently lvm is 251G. I ...
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2answers
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Usage of RESTRICT or No ACTION in FOREIGN KEY Constraints

Sorry if this question is naive, but I was unable to understand possible usage of RESTRICT or No ACTION. Consider a simple database of CREATE TABLE column1 ( first_id int(11) NOT NULL AUTO_INCREMENT, ...
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2answers
264 views

How to recover previous values in Mysql Table?

I have MySQL Innodb table of 14M rows. There was a coloumn called is_disabled which had different values. By mistake I ran the query without the where clause: update url_queue set is_disabled=1 ...
1
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1answer
2k views

How to update mysql my.cnf without getting error?

I updated the MySQL my.conf file and and restarted my server without a problem. As soon as I tried to access a table I received the error mysql #1033 - Incorrect information in file: I reverted ...
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2answers
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What would be the fastest approach to bulk update this mysql table (Innodb)?

I have a table with 100M rows. I am able update my table like 850 updates / minute. How to speed this up? I am using following approach: mysql -uroot < query_file where query_file contains 1M ...
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3answers
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Is it safe to use innodb_flush_log_at_trx_commit = 2

I turned innodb_flush_log_at_trx_commit = 2 and get a very fast write speed. But is it safe be used in production web site?
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0answers
809 views

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2?

Why can I not start mysql server on ubuntu after change the innodb_flush_log_at_trx_commit value to be 2 ? updated to answer the 3 questions: mysql> show variables like 'version%'; ...
5
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2answers
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Recommended structure? %70 write %30 read. 10M row. 200 query/sec. Select, update, insert, search

Followings are what I need to do on my project: 1- If a search term is new and unique, then add the search term 2- Show lastest searched 1000 search terms (I don't need to store dates of all search ...
2
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1answer
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How to recover a crashed innodb table…?

I Have a Innodb table i got the error as mysql> check table City; +-------------------+-------+----------+----------------------------------------------------------+ | Table | Op | ...
5
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1answer
2k views

Find out MySQL index size for a concrete index

In MySQL, for InnoDB engine, how do I find out the size of one of the indexes I have in the same table ? I know I can select the index_length from information_schema.tables, but this gives the total ...
3
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2answers
3k views

LOAD DATA (400k rows) INFILE takes about 7 minutes, cannot kill the “logging slow query” process?

MySQL version: 5.5.13 The query that I'm using: SET AUTOCOMMIT=0; LOAD DATA INFILE '/data10/select_into.outfile/v3_zone_date.out' INTO TABLE v3_zone_date FIELDS TERMINATED BY ','; COMMIT; ...
3
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1answer
288 views

Xen snapshots and live Innodb tables?

I am wondering if I can trust my host doing it's nightly snapshots with live Innodb tables. From what I have read: "Innodb is ACID-compliant, so you can "safely" use fs snapshot with Innodb tables." ...
2
votes
1answer
88 views

Moving the binary location of MySQL for replication

Is it possible to move the contents of /var/lib/mysql when setting up replication instead of doing mysqldump > for export and mysql < for insert on the slave, because in our current setup it takes ...
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1answer
400 views

Why is Mysqlcheck on 5.1.41 still showing as Innodb table corrupted after a table dump and restore?

I had a very large corrupt innodb table. mysqld would crash whenever I did a check table on it. I did a innodb-force-recovery=1 and did a dump of the table. No errors showed up. I dropped the table ...
4
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3answers
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MySQL tables/databases into different disks

I am aware that there is a possibility to have a single database server with many tables/databases, and you can separate some of those tables/databases into separate disks. Lets say you have 5 ...
2
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1answer
731 views

How do you verify that all InnoDB tables are in good shape?

Without using a script, Is there a way to get mysql to check all the tables at once to make sure they're not corrupted?
3
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2answers
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Scheduled optimization of tables in MySQL InnoDB

What is the best way to schedule automatic optimization of tables in a MySQL InnoDB database? Can I use events for example? I have recently had a big performance issue (when querying) with one of the ...
2
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2answers
663 views

mySQL 5.1 changed innodb_log_file_size getting error on restart

In order to optimise my MySQL 5.1 (running on Window 2008 WebServer). I changed a few InnoDB options in my.ini namely the innodb_buffer_pool_size and innodb_log_file_size. But now when I am trying to ...
2
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1answer
571 views

InnoDB not enabled

I have a mysql database that when I run SHOW ENGINES; innodb does not show up as an engine. This seems strange as I have an identical server setup where innodb is enabled and in use. I have checked ...
1
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1answer
429 views

Good strategy to replicate MySQL data

I'm working on MySQL database, well i have a master instance and slaves, and i need to add a new slave to Master. I adopt a simple strategy to do so: Stop slave, import data to new slave, and finally ...
2
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1answer
2k views

importing myisam 5.0 database into a 5.5 innodb server

I have MySQL 5.0 and 5.5 servers (but not a 5.1 server). The 5.0 server is myisam only, the 5.5 default is innodb. I need to move a database from the 5.0 server to the 5.5 server. The database is ...
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1answer
344 views

“SQL_NO_CACHE” for innodb buffer pool

I'm guessing the answer is no, but I was wondering if there was anyway to tell innodb to not store fetched pages in the buffer pool? The reason for looking at doing this is check summing tables. I'd ...
3
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1answer
670 views

mysqladmin debug writes out Current locks but PROCESSLIST and INNODB STATUS don't show any

I'm using the 1.1.8 mysql-cacti-templates to gather metrics on MySQL 5.0.77 (CentOS 5.7). Both the InnoDB Current Lock Waits and InnoDB Lock Structures graphs are charting with Cur[rent] values but ...
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1answer
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Is it possible to change ENUM() lists?

I wasn't sure if changing ENUM() list isn't possible so I made a test. In MySQL v5.1.58 I made a test InnoDB table that contains one field called 'bool' of type ENUM('yes', 'no'). Then I executed... ...
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2answers
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How to join two table and show one query result in MySQL?

I have a table1 (records 3), and table2 (records 3). Where i have field name in both. Now i want to make a result from those two table, which will show me both table records and take only one if there ...
4
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2answers
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Is InnoDB Engine up to speed against Memory Engine?

I am exploring the efficiency of different database engines in MySQL version 5.5.18 to see which is best suited for use with a range query on a dataset of 5 million rows: SELECT P.col1, P.col2, ...
3
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2answers
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MySql - changing innodb_file_per_table for a live db

I have a large MySql DB (150GB) and only now i've noticed that the innodb_file_per_table is set to off which cause the entire DB to be hosted on one single file (ibdata1). i want to active ...