InnoDB : MySQL's ACID-compliant Storage Engine

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what's a reliable way to determine the ideal innodb_thread_concurrency setting?

on an article from 2006 , here they suggest such formula. 2*(number of cpus + Number of Disks) has anyone tried their settings according to this formula ? or do you have any other formula ? our ...
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2answers
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Minimizing database size (Many small tables)

Our database is interesting in that we have a large amount of tables that take up a correspondingly large amount of space, but when we do a MySQL dump of said database, it is surprisingly small. ...
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Pagination, check number of selected records

I am working on pagination for a complex join query and unfortunately I am not sure what's the best way to go... Right now I am thinking about the following solution. Imagine that SELECT id... is the ...
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1answer
92 views

#1025 - Error on rename of table errno: 150 : Table was deleted while tried to assign foreign key

When I tried to assign foreign key to a table named mydb.table1 it was deleted from my database, I could not understand the reason and tried to move on. For this tried to create same table with create ...
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1answer
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MySQL: InnoDB keeps crashing - how to recover?

# free -m total used free shared buffers cached Mem: 48289 35288 13000 0 347 30399 -/+ buffers/cache: 4541 43747 ...
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2answers
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When is it safe to disable InnoDB doublewrite buffering?

MySQL InnoDB allows us to disable doublewrite buffering by setting innodb_doublewrite = 0. Other databases doesn't seem to allow this setting to be tweaked. How could InnoDB still be able to maintain ...
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35 views

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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1answer
3k views

Allocating 8GB memory to MySQL on a 64bit system

Specs - MySQL 5.0.x , Redhat 5.9 , Physical memory - 16GB I am trying to set innodb buffer pool size to 8GB (innodb_buffer_pool_size=8G). When i do, and start mysql, i get following error - ...
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1answer
285 views

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
26 views

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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9 views

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
54 views

Can I lose data if I use InnoDB? [closed]

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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1answer
48 views

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

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
25 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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3answers
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InnoDB row locking - how to implement

I've been looking around now, reading the mysql site and I still can't see exactly how it works. I want to select and row lock the result for writing, write the change and release the lock. ...
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0answers
85 views

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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2answers
2k views

Unable to change engine to MyISAM in MySQL

I have installed MySQL 5.6.10 on Mac OS X 10.6.5. My issue is that MySQL is using InnoDB as its default engine. I have checked following engines are supported in MySQL: show engines\G ...
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1answer
62 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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1answer
404 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> ...
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1answer
51 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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4answers
96 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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3answers
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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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2answers
36 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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1answer
64 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: ...
3
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1answer
324 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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149 views

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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1answer
41 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
28 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 ...
2
votes
1answer
141 views

LOCK=NONE when adding NOT NULL constraint fails with “cannot silently convert NULL values” error despite no NULL values being present

I'm trying to use MySQL's online DDL feature to add a NOT NULL constraint to an InnoDB table without blocking writes to the table. According to manual, this should be possible - the linked table ...
3
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1answer
4k views

Move ibdata1, set innodb_data_file_path

I am in a bit of an awkward situation right now. I have a database with a few large InnoDB tables, one of which is about 145 GiB. I have been running a lot of maintenance on this table in particular, ...
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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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4answers
5k views

Mysql innoDB write operations are extremely slow

I'm having serious performance problems with MySQL and the InnoDB engine. Even the simplest table makes writing operations (creating the table, inserting, updating and deleting) horribly slow, as you ...
2
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1answer
72 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 ...
2
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1answer
69 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
59 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 ...
2
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1answer
38 views

MySQL table indexes change location [closed]

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
27 views

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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2answers
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How can I change the default storage engine in phpmyadmin?

I use InnoDB almost exclusively in my applications. However, if I'm not careful when setting up the table, I forget to change it and phpmyadmin sticks me with MyISAM. Is there a way to change the ...
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0answers
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MySQL 5.6.19a InnoDB Concurrent Insert [closed]

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
22 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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3answers
4k views

How to add column to big table in MySQL

I'm php developer so dont be strict. I have a big table ~5.5gb dump. Our PM decided to make new column in it to perform new feature. Table is InnoDB So what i tried: Alter table in screen with table ...
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1answer
5k views

Amazon RDS MySQL 5.5 Innodb Lock wait timeout exceeded

Ever since we've moved to Amazon RDS, we've had some pretty crazy performance issues, and today we started having locking issues. Because of that, I figured it was just a timeout issue, and went to ...
0
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1answer
298 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 ...
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0answers
29 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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0answers
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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 ...
3
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1answer
726 views

query cache hit value is not changing in my database

The query cache hit value is not changing in my database only for some queries.If I write select * from drugs_info limit 1000; the query cache hit has changed, but if I execute the following ...
2
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1answer
6k views

MySQL: Error reading communication packets

I get this warning in mysql, [Warning] Aborted connection 21 to db: 'MyDB' user: 'MyUser' host: 'localhost' (Got an error reading communication packets) I have been through few topics in google ...
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1answer
228 views

Innodb issue is preventing MySQL from starting [closed]

For some reason mysqld refused to start after I rebooted my server. Now when I try to start it I will get the following error: [root@vps1 ~]# service mysqld restart ERROR! MySQL server PID file ...