InnoDB : MySQL's ACID-compliant Storage Engine

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Slow Query Performance - Can't Debug

I have a MySQL query that I am trying to debug the performance issue but cannot. I know that the majority of the query is reading/processing rows (Sending Data state). However, in the explain output, ...
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trying to understand table size

Can somebody help explain the "data_length" of the table? Why is it so big in my example below of a table with just one column and one row? mysql> create table `network_type` ( `id` int(11) NOT ...
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Percona XtraDB and innodb_flush_log_at_trx_commit=2

I'm running Percona XtraDB on a three nodes cluster. Each one has this piece of configuration: innodb_flush_log_at_trx_commit=2 sync_binlog=0 I perfectly know that this is not the safest ...
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1answer
50 views

Can I lose data if I use InnoDB? [on hold]

During a power failure, is it possible to lose data if I use InnoDB? I remember reading such things.
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ERROR 2013 (HY000) When long string data managed

This is my first question on this community, I'll explain the situation: I have a server with PHP and Mysql on it, on that server I have a wordpress blog. Lately i've been receiving a lot of spam ...
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25.000+ rows - MySQL SELECT consecutive numbers performance issue

I have tried to be as explicit as I could. Below you have the query explained in details What I want to obtain? - I want to SELECT start_number and end_number from a set of consecutive numbers from ...
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1answer
18 views

MySQL InnoDB restoration from hardware failure

One of my server went down due to old hardware failure on a old Dell server that's over 10 years old. I was able to recover the files and got it to a local machine. I want to restore a MySQL instance ...
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181 views
+50

SELECT INTO OUTFILE vs INSERT INTO … SELECT

During my cursory research I have not been able to find a definitive answer on the benefits that SELECT INTO OUTFILE provides over INSERT INTO ... SELECT. Upon reading the docs related to INSERT INTO ...
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1answer
49 views

DELETE seems to hang

The following command: DELETE FROM hours WHERE id IN (SELECT id FROM holdkey WHERE persons_id=60) seems to hang indefinitely. However, the corresponding SELECT * command completes in a fraction of ...
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1answer
26 views

What's the approach to figure out reason for mysql crash?

The database I'm using crashes a lot recently. And I can't find a decent way to dig into the issue. I looked into mysql error log, but don't know how to start. I know there was a "load data infile" ...
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32 views

MySQL/Percona Server is taking long and I'd prefer to skip all this waiting even if it means data loss

Originally posted to https://www.facebook.com/groups/GNUAndLinux/permalink/10155020539805019/ but no replies received. I run Percona Server 5.6.21-70.0-688 x64 on Ubuntu Server 12.04 LTS x64, 64GB ...
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3answers
62 views

Drop Tables with Bigger size

We have a mysql database with a size of 2 TB, in which we have for to five big tables ranging from 110GB to 350GB. When we try to drop these tables the mysql goes to the defunct mode and hangs in that ...
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4answers
76 views

How to backup live mysql database?

I have 12 GB MySQL InnoDB Database with around 800 queries per second. No sooner I start 'mysqldump' over it to make backup I start getting '503' on my website. How do I make backup of my live ...
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31 views

Blob datatype issue with log file

I am getting continuously below error message in mysqld.log [ERROR] InnoDB: The total blob data length (10152274) is greater than 10% of the redo log file size (3072). Please increase ...
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1answer
40 views

InnoDB & Isolation Levels - Aren't repeatable reads a bad thing?

I was reading about InnoDB's isolation levels and it makes sense for the most part, but what I don't get is why are unrepeatable reads a bad thing? Shouldn't it be the other way around? For examples: ...
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1answer
128 views

InnoDB inserts 100 times slower than SQL Server inserts

I have a simple table with two columns: id (autonumber) and name (char(255). When I use C# to insert 100 records in a loop it takes about 30 milliseconds per insert. This is way too slow. So I ...
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MySQL what is the order of the table lock for this query?

An example query looks like this: INSERT INTO Adventure (sword, fighter, quest) SELECT Swords.id, Fighters.id, Quests.id FROM swords Swords, fighters Fighters, quests Quests WHERE Swords._id = ...
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How do I recover from MySQL InnoDB table/index corruption?

While trying to upgrade a database (in place) I got the following error. The server starts up and everything seems to be fine, except that the table mentioned in the message is no longer accessible. ...
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2answers
29 views

MySQL insert position value

I have trouble while inserting the values corresponding to a column: position. I have multiple inserts like this: INSERT INTO category_product(id_category,id_product,position) VALUES(2,1,1); INSERT ...
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34 views

Problems with migration from Amazon RDS MySQL to MariaDB

We are trying to migrate from Amazon RDS MySQL to MariaDB for the performance benefits given by MariaDB. We have copied all the data from Amazon RDS MySQL to MariaDB and the database is up and ...
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1answer
28 views

Can I use xtrabackup to import a database without altering others?

Context: Each time a demo branch is built, I want to download a copy of the prod database and setup it onto the demo server. This way under the MySQL I have X database corresponding to X demos. I ...
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1answer
39 views

How much space is needed to reclaim space from a table in INNODB

I inherited a MySQL InnoDB table that has approximately 200 GB worth of data, as well as several unneeded indices that amount to approximately 500 GB. I've archived approximately 75 percent of the ...
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1answer
18 views

What does FTS_ file mean after converting from MyISAM to InnoDB?

I have convert some tables in database from MyISAM to InnoDB. After that, I see some modification on file system. The size of database is grown up, from 2.8GB to 4.8GB and there are many file with ...
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1answer
34 views

Does a database update force index rebuild regardless of updated field?

With MySQL (InnoDB), I understand that having indexes slow down UPDATE queries. I would like to know if this happens regardless of what fields are updated. For example, if I have a table with 20 ...
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1answer
24 views

MySQL table indexes change location [on hold]

Is it possible to move the MySQL Table indexes to another location rather than "datadir" ? for example a ssd drive or memory partition ?
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1answer
37 views

MySQL no query cache hits

My database have been up and running for a while with query cache enabled, but there are 0 hits. I have tried to check the settings but I am not sure what the problem is. Using InnoDB. mysql> SHOW ...
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1answer
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75% of RAM for Innodb_buffer_pool size

I have read many documentation including percona and MariaDB documentation where they recommend setting innodb_buffer_pool_size to 70-80% of RAM. My question is, is that total RAM or available RAM? ...
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42 views

MySQL 5.6.19a InnoDB Concurrent Insert

I've looked through most of the threads on this topic but still had question I was hoping someone would be gracious enough to help with. I am seeing low CPU usage and write latency but transaction ...
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0answers
21 views

Need advice on optimizing database on a recurring basis

I have a search engine with approx 3.5 million rows in the searchable table. There are many suppliers that feed into the table each day, so primary keys are constantly being removed and added and the ...
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2answers
79 views

MySQL any way to import a huge (32 GB) sql dump faster?

I have this huge 32 GB sql dump that I need to import into MySQL. I haven't had to import such a huge sql dump before. I did the usual: mysql -uroot dbname < dbname.sql It is taking too long. ...
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1answer
38 views

Statements in State “Copying to tmp table” disrupt performance [on hold]

On a MySQL database (version 5.1.73) a Magento-Shop executes a statement (A) that uses distinct, see http://pastebin.com/A2sy45nF and therefore is "Using temporary" according to "explain". ...
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1answer
47 views

How to batch multiple insert statements for database dump with MySQL?

I have a MySQL database with some large tables. In particular, the largest table (by far) currently has ~11,000,000 rows. According to the a query I ran, the table clocks in at around 1.7GB, but it's ...
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25 views

Advice on table structure change

I am in the process of converting an Access application that stores and reports evaluations to being web-based using php and mysql. I have converted the structure and data over from Access and I have ...
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37 views

How to notice data lost in innodb engine

I have a web-application installed in some desktop pc, and I experienced some troubles with mysql innodb. In case of hardware fault (disk failure) or just power fault I lost many data in my database ...
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1answer
54 views

How mysql (innodb) handles auto increment column

I am working on a OLTP environment with multiple parallel write operation. I found this in documentation about auto increment locking but still i am interested to know much about it in details. Can ...
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2answers
111 views

Do I need to reindex mysql table after bulk delete?

I have a table in MySQL with a lot of INSERT and SELECT at every second. And there is a bulk delete of some older data once in a day. Do I need to reindex the table after delete? I want to increase ...
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2answers
63 views

Do I need to reindex my table in mysql after delete?

I have a table in mysql with a lot of INSERT and SELECT at every second. And there is a bulk delete of some older data once in a day. Do I need to reindex the table after delete? I want to increase ...
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1answer
33 views

MySQL InnoDB + high table creation-destruction rate

We are transferring a microsoft SQL based website (+app + plugins) structure to MySQL. The website has a high "Content + Comments + Activity Tracking" behaviour. Mainly because of the activity ...
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32 views

mysql uses a lot of virtual memory

I've a mysql server with a lot of small size innodb databases (each db also contains a lot of small tables) & 6GB of RAM dedicated to mysql server. Recently I've increased my ...
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Can't seem to optimize joined select query

Can't seem to figure this one out. Query is taking upwards of 7-8 seconds which is just not acceptable and seems as though it will get worse as the table(s) get larger. Without going into a ton of ...
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23 views

moving binary database folder is causing issues with innodb tables

so I have a mix of myisam and innodb tables on a database. (its a pretty big db 30gb) I copied the folder of the database from one server to the next /var/lib/mysql/databasename well the myisam tables ...
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MySQL Inno DB Crash

This is the log of the crash. Basically every time I run a query it looses connection an crash. 2014-11-03 19:46:42 58021 [Note] Event Scheduler: Loaded 0 events 2014-11-03 19:46:42 58021 [Note] ...
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Does InnoDB Log Files take RAM space or Disk Space

When I set InnoDB Log File size to 512M, does it take the space (512M * 2) from RAM or the SSD Disk space? When I explored, I can see that the log files are located inside /var/lib/mysql folder. So ...
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MySQL Crash due to “InnoDB Assertion” after Query

Current setup: Ubuntu 12.04 LTS MySQL 5.5.31 Current Use: Slave - Only ETL queries 64 GB RAM Intel(R) Xeon(R) CPU X5670 @ 2.93GHz - 12 Cores - Hyperthreaded (24 Logical) MySQL Main Settings: ...
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1answer
27 views

Move a MySQL 5.5 database to a server running MySQL 5.1

I have a backup of a MySQL database (using InnoDB) from a Windows machine that was running MySQL 5.5. The Windows machine is no longer available and now I need to import the backup into an Ubuntu box ...
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1answer
25 views

Query perfomance with multiple JOINs on MyISAM-based DB

I'm working with Enron Email Dataset in MySQL database. After I executed data import from dump-file into MyISAM-based DB, I got the set of tables without any connections between them via foreign keys. ...
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62 views

How to resolve “InnoDB data dictionary has tablespace id N” [duplicate]

I recently messsed up a migration to table-per-file for my dbs. In the end I (thought) I dropped all dbs, deleted any left over files, and then started over from scratch, importing only dbs I needed ...
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241 views

Hyperthreading & MySQL InnoDB Thread Concurrency Performance

I have a dedicated DB Server with the following specs" Ubuntu 12.04 LTS Server Intel(R) Xeon(R) CPU X5670 @ 2.93GHz 12 Cores MySQL 5.5.29 64 GB RAM RAID10 We are currently doing Hyperthreading ...
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MySQL - Pending flush list, aio write, and the innodb_use_native_aio parameter

I'm running an Amazon RDS instance with MySQL 5.5. The applications using that are very write intensive, and there's over 1TB of data. Everything was fine until a recent minor version upgrade and ...
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75 views

Best Innodb Buffer Pool Size for 8GB RAM?

I found out that my MySQL server is configured with only 128MB for innodb_buffer_pool_size. That is not enough considering that I have a 8GB RAM server. It hosts MySQL server and an Apache/Catalina ...