InnoDB : MySQL's ACID-compliant Storage Engine

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How to UPDATE a table for the level of parents in a column?

I have a table with internal parents as id parent parent_level 1 NULL 1 2 1 2 3 1 2 4 3 3 where parent has a FK to id. How can I update the table ...
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369 views

How to increase MySQL performance with joins

I have a MySQL database with InnoDB engine. Particularly one of my queries became very slow. The query is shown below: SELECT t1.`ARTREF1` FROM `lijnen` AS t3 INNER JOIN (`kortingen` AS t2, ...
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175 views

MySQL command querying all MyISAM database

I would appreciate if anyone could help me of what's the proper command in MySQL to query all database for having "MyISAM" engine. I need to convert all DB & tables from MyISAM to InnoDB.
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63 views

Do regular ALTERs weaken the performance?

In a project, we need to frequently ALTER the tables to delete or add columns. I wonder if this weakens the database performance in long term. If it has a considerable negative impact, what is the ...
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1answer
2k views

MySQL: sysbench test - InnoDB vs Memory tables

I've done some tests in order to investigate performance issue on the new HP Gen8 server (Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz) I've created two tables, first one is using InnoDB storage engine ...
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201 views

Sleeping connections

I have a dedicated MySQL server(8GB) with following configuration. [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql lower_case_table_names = 1 ...
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1k views

Query getting periodically stuck in 'copying to tmp table' state, never completes

I am running Wordpress on a dedicated server with a MySQL backend. I have a query that usually takes <1 second to execute, but periodically, this query will get stuck in a 'copying to tmp table' ...
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3k views

bulk_insert_buffer_size and InnoDB

I read the following on this page http://dev.mysql.com/doc/mysql/en/server-system-variables.html bulk_insert_buffer_size MyISAM uses a special tree-like cache to make bulk inserts faster for ...
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1answer
386 views

Deleting 200M+ rows from InnoDB table

Basically, we have a table with the following structure: CREATE TABLE `reqs` ( `id` INT(10) NOT NULL AUTO_INCREMENT, `reqid` BIGINT(20) NOT NULL, `from` BIGINT(20) NOT NULL, `to` ...
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Percona Xtradb Cluster : How to speed up insert?

I recently installed a 3 full master node cluster based on Percona Xtradb (very easy install). But now i need to make some tuning to increase INSERT/UPDATE requests. Actually, i made around 100 ...
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1answer
1k views

mysql innodb space x did not exist in memory

Into my innodb log I got the errors below. How to fix? What did it mean? Some tables are corrupted but not all. InnoDB: space id 1753 did not exist in memory. Retrying an open. 130906 16:31:27 ...
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139 views

MySQL failures after changing innodb_flush_method to O_DIRECT and innodb_log_file_size

We changed innodb_flush_method to O_DIRECT, innodb_log_file_size to a bigger value, and 3 other things (innodb_buffer_pool_size, innodb_additional_mem_pool_size, innodb_log_buffer_size) while MySQL ...
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1answer
887 views

Spatial Index on an InnoDB table

I have a database which is in InnoDB, because I wanted consistency (cascading delete). Now, I want to use spatial indexes for selecting rows ordered by geometric distance. However, spatial indexes ...
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1answer
298 views

MySQL looking up more rows than needed (indexing issue)

In our MySQL 5.5 database, we have following InnoDB table with 30M+ rows: +----------------+-------------+-----------------+--------+ | participant_id | question_id | given_answer_id | status | ...
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1answer
245 views

Combining multiple left join for one single line

We have a query as below. SELECT tblSData.header, tblEAlert.eMessage FROM tblSData LEFT JOIN tblEAlert ON tblSData.sDataID=tblEAlert.sDataID Where tblSData.aID=".$aID." Order By tblSData.dateTimer ...
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213 views

Drupal database doesn't work after MySQL restart

I've installed Drupal 7x on my local XAMPP 1.8.3 Server. Everything went fine but after adding some modules, changing the drupal theme and restarting the MySQL Server, the MySQL Server is dropping ...
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333 views

MyISAM vs InnoDB for Forums [closed]

I want to design a forum script with MySql. Which database engine would have better performance? MyISAM or InnoDB ?
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How to prevent “ibdata files do not match the log sequence number”?

I am dealing with a very large set of databases that are all innodb. I've enountered this on mysql restart too many times for my comfort: ibdata files do not match the log sequence number But I've ...
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1answer
443 views

Deadlock from mysqldump --single-transaction, is it possible?

Is it possible to get a deadlock if you ran mysqldump with the argument --single-transaction ? or any other complication ? If it is used to backup a live site with many other querys running at the ...
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671 views

Incorrect information in .frm file after a power outage?

CentOS release 6.3 (Final) x86_64 mysql Ver 14.14 Distrib 5.5.31, for Linux (x86_64) using readline 5.1 SHOW SLAVE STATUS\G: Slave_IO_Running: Yes Slave_SQL_Running: No ...
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1answer
15k views

What is causing Waiting for table level lock errors?

We got the database hanging twice already and trying to find a cause. show processlist Waiting for global read lock | INSERT INTO {myisam_table} ... In here the disk space was full so we thought ...
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566 views

MySQL InnoDB slow inserts

I'm currently struggling with an MySQL Community Server 5.5.27 when inserting large numbers of rows into a table. We're running a 24 core Intel Xeon machine with an SSD software raid array. I did some ...
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1answer
641 views

MySQL Performance Issues

Over the past 3 weeks we have been having bottle-necking issues at our MySQL server. I have been using MonYOG to watch the processlist in an attempt to get a grasp on the issues. We are aware that ...
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1answer
4k views

Recover the disk space after deleting rows from table

I deleted millions of rows from one of the table with innodb engine. I know that I need to run optimize table to recover the space. But running that will cause lock on the table, which will affect the ...
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1answer
416 views

MySQL / Fusion IO Configuration Question

I need a little configuration optimization. I think what I have is pretty good but feel like there's still room for improvement. Current Config [mysqld] user=mysql datadir=/var/lib/mysql ...
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1answer
1k views

Finding swap causes of MySQL

In my centos 6.3 server I have a MySQL 5.5.33 database. It has 17 tables (15 InnoDB, 2 MyISAM) and total records 6.7M rows. I refactored my schemas and added indexes for my slow logs. My average query ...
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2answers
651 views

Setting innodb_buffer_pool_size in for Mysql

We have a dedicated DB box with with 8 GB of RAM and running Redhat linux 64 bit OS. Our MySQL Data + Index size almost 7.8 GB. About setting innodb_buffer_pool_size, I have read 2 suggestions Set ...
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16k 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 ...
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1answer
3k views

What happens if the mysql database's innodb log files are lost?

What I did was /etc/init.d/mysql stop then removed the files: ib_logfile0, ib_logfile1 then modified my.cnf file, variable: innodb_log_file_size and then: /etc/init.d/mysql start and allowed ...
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3answers
8k views

Why does MySQL ignore the index even on force for this order by?

I run an EXPLAIN: mysql> explain select last_name from employees order by last_name; +----+-------------+-----------+------+---------------+------+---------+------+-------+----------------+ | ...
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1answer
156 views

Why isn't the rows of an EXPLAIN accurate?

I have the following table: mysql> select count(*) from employees; +----------+ | count(*) | +----------+ | 10000 | +----------+ 1 row in set (0.03 sec) I do an EXPLAIN: ...
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How do I determine how much data is being written per day through insert, update and delete operations?

The longevity of SSDs is largely determined by the amount of bytes written by insert, update and delete operations. What is the best way to accurately determine how much data is being written by ...
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3answers
1k views

Backup / Export data from MySQL 5.5 attachments table keeps failing!

Can anyone please help! - I have a large table in a MySQL 5.5 database. It is a table which holds a mixture of blobs/binary data and just data rows with links to file paths. It has just over a million ...
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103 views

Any drawback to lots of creating and renaming tables at InnoDB?

I'm trying to optimize an important cronjob for my program, and what it basically does is generate a long list of user ids with their score points. I have a table called user_ranks and it will bulk ...
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1answer
556 views

TokuDB database size unknown in phpmyadmin

In mysql server, I installed the TokuDB storage engine. I converted database engine InnoDB to TokuDB, but my table sizes show unknown in phpmyadmin.
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124 views

Increased server load after InnoDB deadlock

I am using InnoDB instead of MyISAM for a couple of months right now, and it has really optimized my game database-wise. I was aware of the danger of deadlocks, but hadn't had any problems with it, ...
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1answer
2k views

InnoDB: Error: pthread_create returned 12

have installed MySQL in a particular folder. I was able to run the server and create accounts, databases etc. However, now whenever I try to start the server, I get an error: $ mysqld_safe ...
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1answer
1k views

Insert Speeds for large batches

In my application, my INSERTs seem to be taking a major chunk of the time. I have a large number of objects in memory (~40-50,000) which i want to insert into a table. Lets take a sample table ...
2
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1answer
99 views

Why is it slower to access records at the end of the database?

I have a mysql innodb database running with some 200k records, and I'm having some unexpected slowdown when accessing records near the end of the database. Specifically, it is taking .10 seconds to ...
3
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1answer
925 views

How to convert innodb engine tables to tokudb engine

Hi I want to migarate my server newly installed tokudb engine. i want to convert each table of database from innodb to tokudb. How can I do that using sed command ?
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2answers
5k views

MySQL 5.5 High CPU Usage

I have been working with a client with high traffic website(500k visitors and 600-800 active users at any given time). This uses wordpress and the DB is using MyISAM engine. The problem we had was ...
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1answer
1k views

Speeding up a NOT IN subquery

Good evening, I'm currently up to try to improve the performance of some of my queries. As far as I know, statements like "IN" or "NOT IN" are even faster with a large amount of values if a subquery ...
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3answers
5k views

Transaction Rollback on DROP DATABASE

Does MySQL use transactions for DROP DATABASE... statement (all tables use InnoDB engine)? Basically I would like to know if any data will be lost if I kill DROP DATABASE... query while it's running? ...
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2answers
279 views

Specific disadvantages to storing infrequently accessed large files in a large database

I have heard many times across the web that it is, for various reasons, a bad idea to store files directly in a database, the preferred method being to store filenames in the database, and files ...
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3k views

How to optimize MySQL for large BLOB updates

I have a table that holds large BLOBs (up to 10M), and is updated frequently. The problem is that UPDATE statements can take up to 1 second to execute, and due to app design this blocks UI. I need to ...
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468 views

InnoDB, Hash Table, Reference Table and Fragmentation

I have a big list of domains and URLs that I store in a database, there are around 150M domains and 300M URLs, I'm using InnoDB to store each in the format: CREATE TABLE IF NOT EXISTS `domains_list` ...
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1answer
3k views

Putting a Select statement in a transaction

What is the difference between these 2 queries: start transaction; select * From orders Where id=1; UPDATE orders SET username="John" Where id=1; commit; And without transaction: select * From ...
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2answers
2k views

Remove InnoDB files (ibdata1 and iblog files) after migration to MyISAM

I changed the only two InnoDB tables on a replication slave to MyISAM, so the slave now only has MyISAM tables. Can I now remove the ibdata1 file completely?
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6k views

InnoDB log sequence number is in the future

130711 23:03:40 InnoDB: Error: page 23 log sequence number 3336825872455 InnoDB: is in the future! Current system log sequence number 235089. InnoDB: Your database may be corrupt or you may have ...
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3answers
11k views

How to estimate/predict data size and index size of a table in MySQL

I am finding what is the best way to estimate size of a table for that i have studied lot of blogs and forums but unable to find any accurate answer For an example we have a table City with InnoDB ...