InnoDB : MySQL's ACID-compliant Storage Engine

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MySQL: To use MYISAM or INNODB engine? (plot twist enclosed)

We use INNODB for all of our tables, but I have one special table, a 100+ GB reference table (only read-queries against it). We are loading changes to this table in a nightly batch job using LOAD ...
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2answers
12k views

Finding and fixing InnoDB index corruption

I encountered a new issue yesterday with one of my MySQL 5.5 slave DBs that runs on EC2 in AWS. The DB was created from a snapshot of another slave. The data is correct, but for at least one table a ...
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1answer
4k views

Very Slow MySQL Queries, even with indexes

I have a relatively large 4-deep relational data setup like this: client_applications: (potentially 1,000's of records)    - ...    - account_id    - ...
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1answer
697 views

InnoDB row level locks without SELECTs?

I have several (>30) MySQL clients inserting into InnoDB tables concurrently. I keep encountering lock wait timeouts and can't figure out why. Here is the situation: Each client runs the following ...
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2answers
1k views

Database space doesn't match ibdata1 size

I'm using InnoDB database with a single file configuration (in /var), so no innodb_file_per_table. In the MySql workbench, when I query for the databases used space, with this query SELECT ...
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969 views

Queries getting stuck on very simple COUNT queries

process list: | 16004 | metrics | xxx:64616 | metrics | Query | 29064 | Sending data | SELECT COUNT(*) FROM Plugin where LastUpdated >= '1356856200' | ...
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1answer
13k views

Mysql slowly uses memory until it starts to use swap

I am running a 1gb of RAM rackspace database server. For some reason in about 2 days the memory usage goes from using very little swap, to using 100mb. If I don't restart sql it will keep using more ...
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1answer
6k views

Is there a progress indicator for OPTIMIZE TABLE progress?

MySQL 5.1.4x (Windows) | Innodb I recently purged data from a mySQL DB (a few hundred thousand rows) and I'm planning to use OPTIMIZE TABLE LOGTABLEFOO1,LOGTABLEFOO2,LOGTABLEFOO3; to reduce the ...
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317 views

Set up replication and migrate to InnoDB with low downtime

Current situation is this: I have a large legacy DB using only MyISAM tables, the size of whole DB is 4GiB, one of the tables contains over 10 million rows, so it is pretty large. The database is ...
3
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1answer
943 views

Mysql Server optimization tips needed! (InnoDB)

I've recently been trying to optimize our mysql server but I've encountered some pretty serious problems on the way. We're running a game server which is coded in C#. We have two dedicated servers. ...
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1answer
549 views

Fill ibdata1 With Zeros/Nulls/etc Or Change A Table's Tablespace

I have a MySQL 5.5 server running on CentOS 6. The MySQL package is a MySQL-released version (MySQL-server-5.5.28-1.el6.x86_64), not the stock CentOS one. I have moved an existing database over from a ...
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4k views

How to UPDATE a column to SET previous row value to NULL cells?

I have a table as id value 1 music 2 3 movie 4 5 6 book 7 8 Some values are missing, and I want to assign the value of previous row to produce id value 1 music 2 music 3 movie 4 ...
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MySQL InnoDB locks primary key on delete even in READ COMMITTED

Preface Our application runs several threads that execute DELETE queries in parallel. The queries affect isolated data, i.e. there should be no possibility that concurrent DELETE occurs on the same ...
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1answer
2k views

Where is the MySQL variable - innodb_flush_method?

I would like to tweak the value of innodb_flush_method to find out its performance impact on a database server. That variable is listed when I run the command SHOW VARIABLES. But I could not find it ...
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2answers
459 views

Bin logs with high i/o

I'm DBA (IBM Informix) and already use MySQL with Drupal , where have low workload. So, my knowledge of MySQL is minimal. Few days ago I start use MySQL with a basic configuration as back-end for a ...
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2answers
5k views

Deleting MySQL table with pending transactions

Is there a way to delete an InnoDB table or database with pending transactions in MySQL (preferably on file system level)? What happened: I use MySQL 5.5.28 and ran LOAD DATA INFILE… to import a ...
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1answer
392 views

mysql freeze/crash on JOIN

here is query: SELECT nw.news_id, nw.title, nw.description, nw.url, nw.date, nw.image, nw.status, src.title as src_title, src.keyword as src_keyword, src.url as src_url, src.icon as ...
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2answers
1k views

How to split a string to and get info from another table in mysql

I have a system to assign score for each sentence stored in a column: TABLE 1: word_scores word score this 3 is 4 a 5 test 1 another 0 sentence 8 TABLE 2: ...
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1answer
269 views

Which MySQL storage engine is the most similar to ARCHIVE when that is not available?

I have a table that contains a log of events that is written to often and read very infrequently by comparison. I would love to use the ARCHIVE engine, because it is basically designed for exactly ...
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2answers
2k views

MySQL Enterprise Backup error: Log scan was only able to reach xxxx

I use MySQL Enterprise Backup to make incremental backups, but when I apply a restore (copy-back), I can't remake a backup. I get this error: mysqlbackup: ERROR: Log scan was only able to reach ...
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1answer
793 views

LOAD DATA INFILE blocks on concurrent use against MyISAM tables

I'm having trouble loading data into MyISAM table(s) concurrently using LOAD DATA INFILE. The loading operation works fine in isolation. Trying to do LOAD DATA INFILE operations concurrently, blocks ...
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Dynamic change to innodb_flush_log_at_trx_commit

This is related to this question. It does help to get better performance for InnoDB tables. According to MySQL manual, innodb_flush_log_at_trx_commit is a global dynamic variable. Thus, I can change ...
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3answers
5k views

InnoDB insertion faster

I'm a graduate school student researching OLAP with Mondrian OLAP. So I want to insert data into InnoDB (MySQL 5.5) faster at the initial loading. In this environment, the only user is me, so I think ...
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186 views

Tablestructure for fast inserts/deletes with foreign keys

Current Situation We have a table called c with ca. 300,000 rows. In this table we store the competitors for a specific product. Example: id | competitors | some infos about competitor | ...
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MySQL INNODB corruption after server crash during concurrent truncate command

My server crashed today I think due to a concurrent truncate table command on one of our INNODB tables. The server could be restarted, but after it starts up, everytime I try to issue an SQL command, ...
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797 views

How to concatenate a column after x rows?

I have a table with columns object varchar(255), frequency tinyint(3) unsigned, I want to concatenate the objects if the sum of frequencies reach a value. Currently I am doing this in PHP as .. ...
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1answer
521 views

innodb changing row format doesn't decrease table size? [closed]

We're currently using MySQL with innodb and we have some large tables that are compact in row format. When I change the row format to compressed we are still seeing the same size for the table. Anyone ...
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1answer
1k views

InnoDB, What would cause: “db1/tableABC contains 6 indexes inside InnoDB, which is different from the number of indexes 5 defined in MySQL”

MySQL 5.5.24 . We have InnoDB tables that grew almost by double (from 50GB to 100GB - file-per-table enabled) in a few weeks due to a project we are working on. The tables were freshly dumped and ...
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2answers
1k views

How to run a cold backup with Linux/tar without shutting down MySQL slave?

I run the following before tar-ing up the data directory: STOP SLAVE; FLUSH TABLES WITH READ LOCK; FLUSH LOGS; However, tar will sometimes complain that the ibdata* and ib_logfiles* files are ...
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2answers
472 views

Can I use a foreign key index as a shortcut to getting a row count in an INNODB table?

I have a table that has a large number of rows in it. The primary key (an auto-incrementing integer) is, by default, indexed. While waiting for a row count to be returned I did an EXPLAIN in another ...
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613 views

Unable to take backup of mysql database using Xtrabackup

I am trying to take mysql backup without any downtime but unable to take the backup using Xtrabackup . Actual Database is almost about 40+ GB in size. I am trying to first satisfy myself. Hence, I ...
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453 views

“InnoDB: error clustered record for sec rec not found” MySQL 5.5.28

We have a high-end server, 128GB RAM, 32 Core , Xeon, SSD RAID 10 - running Ubuntu 12.04 with MySQL 5.5.28. During high load, randomly we got the below error. MySQLcheck, innochecksum shows no ...
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jdbc+mysql: “Deadlock found when trying to get lock; try restarting transaction”

After recovering from a disk-full problem, I started getting these errors in my logs: java.sql.BatchUpdateException: Deadlock found when trying to get lock; try restarting transaction at ...
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Resolving DUPLICATE for a column with UNIQUE

I have a few column with UNIQUE INDEX. In some queries, duplicates should be acceptable, in which a postfix should be added to the value. For example, if test title exits, we change it to test ...
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MySQL 5.5 : (InnoDB) - Manually edited an .ibd file to test recovery, now entire MySQL installation is broken!

So I wanted to test MySQL recovery from Innodb corruption. file-per-table is enabled. I have a few test db's on the MySQL instance. I shutdown mysql. Manually edited/added random characters to an ...
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195 views

Is it always bad to use SELECT * FROM?

It is widely recommended NOT to use SELECT *. I understand this, as it is not a good idea to bring the entire row into memory, when only a few cells are needed. Is it still bad to use SELECT * when ...
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Innodb, MySQL 5.5.28 - Segmentation Signal 11 faults, on high load. .. my.cnf file included

We have a high-end server, 128GB RAM, 32 Core , Xeon, SSD RAID 10 - running Ubuntu 12.04 with MySQL 5.5.28 . Doing random imports to large InnoDB tables, over 50+ gigs, randomly after a few hours of ...
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649 views

I have multiple ibdata files : What should I do with them?

I have 3 different ibdata files on disk. What is the difference between them? Can I remove some of them? The goal is to migrate the files from C: to E:... I'm on MySQL 5.0.x... Directory of C:\MySQL ...
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How long can Deadlock info hold in innodb status page?

When I run SHOW ENGINE INNODB STATUS\G, I can see this timestamp ------------------------ LATEST DETECTED DEADLOCK ------------------------ 121118 17:14:31 Questions Any idea how long Deadlock ...
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mysqlcheck to optimize innodb tables — performance/scheduling

I'm attempting to optimize tables on a very large, production database server. I'm looking for statistics or benchmarks on how long it will take for certain sized databases/tables. Is there a ...
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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 ...
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773 views

inner join on PK with extra criteria slow despite indices?

Given the two tables below I am struggling to understand: why is the third query slow even though first two queries are fast what exactly is EXPLAIN saying can I do anything to significantly speed ...
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1answer
3k views

InnoDB Performance Tuning

I'm new to database administration so please excuse any omissions of what would seem like basic info to provide for this problem. I'm a RoR developer and our team is currently short a DBA, so we're ...
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What is an accepted method of keeping old data in MySQL?

I think this may be more of a programming question, but since it directly relates to MySQL, I wanted to ask it here. Some background: I am running an application whereby users can take tests using ...
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237 views

Does having Default Database Engine MyISAM and keeping InnoDB tags in my.ini create any problem?

Recently I am getting table corruption issue very often and every time when I check the logs it says "Binlog has bad magic number; It's not a binary log file that can be used by this version of MySQL" ...
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1answer
767 views

Monstrous query hanging on “copying to tmp table” in MySQL

I have a huge query being run by one of my developers which seems to hang no matter which performance tunables I adjust. Though I'm somewhat of novice at writing SQL queries, at first glance the ...
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Must an index cover all selected columns for it to be used for ORDER BY?

Over at SO, someone recently asked Why isn't ORDER BY using the index? The situation involved a simple InnoDB table in MySQL comprising three columns and 10k rows. One of the columns, an integer, ...
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2answers
2k views

How to insert into junction table using triggers

Sorry in advance if this is "basic SQL." I wanted to know how to update my junction tables automatically. For example, these are my tables. Artist and Song are base tables and SongArtist is the ...
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2k views

How to know the current log sequence number in 5.0.X

I would like to test the optimal value for iblog files on my mysql which is 5.0.77 I found the below procedure in mysqlperformance blog: ...
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169 views

What MySQL storage engine and table schema should I use?

I am making a web project and I created necessary and the most important table, but I am not sure that I did it right. In this site users will post data like text, picture, text's category, etc. I ...