MyISAM is the non-transactional storage engine for MySQL. It provides high-speed storage and retrieval, as well as fulltext searching capabilities. In addition, it is the default storage engine type for versions of MySQL prior to 5.5.

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Tuning MySQL MyISAM for large joined updates

I have a database with two tables that I would consider small. I need to update values on the larger of the two tables (1,100,000 rows, 75M MYD, 120M MYI) from the join of the two tables. The smaller ...
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1k views

How to configure my.cnf for Mysql 5.1, which is using too much CPU?

I am new Database engineer. I am having trouble in my server which is using too much CPU on database query(simple count statement). I have googled about it, so i found out it depends on system ...
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434 views

MyISAM : Should I be concerned by these warnings?

I restored some tables from recent Databases backups. Because Im supporting a legacy system that only uses MyISAM tables in their DBs, for backing up I used a little script that pretty much copies all ...
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MySQL instance stalling “doing SYNC index”

Problem An instance of MySQL 5.6.20 running (mostly just) a database with InnoDB tables is exhibiting occasional stalls for all update operations for the duration of 1-4 minutes with all INSERT, ...
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1answer
714 views

INSERT take too much time

I have in my MySQL DB a few tables Most of the time, I'm only doing INSERT in my db. I have up to 4 connections to the DB, each one inserting into a different table. There cannot be two connections ...
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Migrated servers… Innodb tables stayed innodb, but database is showns as MyISAM. Problem?

I moved servers. I exported DB on old, imported to new. Kept getting syntax error on import until I tried no compression. Weird, but it worked. I was skeptical so I compared the two carefully and ...
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1answer
121 views

Need help in increasing maximum table size

Two of the tables vb_post, vb_profilevisitor getting corrupted again and again. The hosting company suggested the following: Looks like the problem is that the .MYD table was converted to a .TMD ...
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142 views

WordPress MySQL writes during “Flush Tables With Read Lock” are rejected instead of being queued

I'm running into an odd issue when setting MySQL into a brief read-only mode for backup. Reads continue fine during that "read only" minute, but writes are just rejected instead of being queued to ...
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1answer
300 views

MySQL fulltext selection performance

I have 1.5M rows in a table. Following is the table create code: CREATE TABLE `jobs` ( `id` INT(8) NOT NULL AUTO_INCREMENT, `job_id` VARCHAR(50) NOT NULL DEFAULT '', `title` VARCHAR(255) ...
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2answers
42 views

Database Tuning Issues

I'm not a DBA so looking for some advice on tuning a MySQL (MyISAM) database. I've found that during peak hours we are getting pretty severe load spikes which are slowing down the web front-end. I've ...
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1answer
208 views

How to update a (very) large table without locking in MySQL

I have a large table (58+ million records) which represents a relation between two records (player and target) in a second table. Unfortunately, whoever designed our schema didn't think things ...
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1answer
2k views

mysqlcheck --repair a specific table?

I logged in my server via SSH and committed a "repair table xxx" query on a MyISAM table with 34 million rows and 69GB of data. Unfortunately the SSH connection was lost. When I logged back in I found ...
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2answers
87 views

Add UNIQUE index fails with duplicate entry error, but no duplicates found

Given table: CREATE TABLE mytable ( field_a CHAR(15) NOT NULL DEFAULT '', field_b MEDIUMINT UNSIGNED NOT NULL DEFAULT 0, field_c SMALLINT UNSIGNED NOT NULL DEFAULT 0, field_d SMALLINT ...
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25 views

Tuning Issue / Temporary Tables

I've got a MySQL database (MyISAM) that handles a lot of read/writes and uses temporary tables quite frequently. Recently it's started having massive load spikes at peak load, and noticed that there ...
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1answer
718 views

Why would the size of MySQL MyISAM table indexes (aka MYI file) not match after mysqldump import?

I've been archiving some MySQL (version 5.0.96) MyISAM tables locally and deleting from my server after checking the data. Every time the process has been pretty similar and comes off mostly without a ...
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1answer
90 views

Configuration required for a big mysql database around 20GB

I need to host a single machine database (constraints), wherein the database size is roughly 20gb. Most of the tables are in MyISAM. Any way I can actually run it with decent speed ? Alternatives I ...
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1answer
50 views

MySQL: OPTIMIZE TABLE vs. myisamchk

I have a very large table (~50GB) and periodically rows are purged from it and I want to run OPTIMIZE TABLE to recover the space. But I do not have enough space to run it. If I do run it the server ...
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2answers
49 views

Disable Primary Key on MyISAM Table

I wanted to speed up a large insert bulk by disabling keys. So I ran the following command on a MyISAM table: alter table my_table disable keys; When I execute show index from answer_2011, I see a ...
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2answers
123 views

Invision Power Board 3.4.6 - mysql locks during query with pending updates

about 2 weeks ago, we started experiencing random lockups and slowdowns on our forums. We've been running this site for around 6 years minimum with no issues. the site and db are on dedicated vms. The ...
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1answer
45 views

Cannot delete MySQL trigger. Appears in information_schema, but no .TRN file

I have a MySQL database with a few tables and triggers. A process was trying to drop one of the triggers and it failed with the following error: Malformed file type header in file 'trigger_name.TRN' ...
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61 views

MySQL - high CPU usage (MyISAm tables) in LAMP

I have a LMAP stack running on Centos 6.6. Here is the detail which may help. # cat /etc/redhat-release CentOS release 6.6 (Final) MySql version # rpm -qa | grep -i mysql ...
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Database storage engine and performance [duplicate]

What will be the performance issue when I change my database storage type from MyISAM to InnoDB?
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4answers
56k views

Which is faster, InnoDB or MyISAM?

How can MyISAM be "faster" than InnoDB if MyISAM needs to do disk reads for the data? InnoDB uses the buffer pool for indexes and data, and MyISAM just for the index?
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1answer
49 views

How important is InnoDB versus MyISAM? [duplicate]

Does it really matter if the default storage engine is InnoDB? My default storage engine is MyISAM
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135 views

Are TEXT fields stored separately from the row in MySQL-ISAM?

We have a "notes" table and some of the queries are getting very slow even though we're not searching on the note contents. We're wondering if moving the note content into a separate table would speed ...
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2answers
69 views

Optimal engine for small lookup tables in MySQL

I have following question: I am designing web application with several dozens of small lookup tables: These tables usualy contain three columns (ID, Name, Description) and a couple of rows (mostly ...
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1answer
36 views

Confused over table_open_cache

I've been reading about the table_open_cache and I'm slightly confused about how big it should be, I've seen conflicting advice. My DB is running on MyISAM and has 199 tables. I ran into an issue ...
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2answers
42 views

Fixing MyISAM database without losing data

My old server was crashed but I was able to recover the databases from MySQL through testdrive. I'm trying to dump a database using mysqldump but it gives error for certain tables are crashed and ...
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1answer
69 views

How to speed up query containing concat() in WHERE clause?

In my company we use a commercial software running with mysql 5.5 (MyISAM) that often executes a query of this form: SELECT table1.attrib1 FROM table2, table1 WHERE table2.status = 'Active' ...
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31 views

Got an error from unknown thread, /pb2/build/sb_0-13157587-1410170252.03/rpm/BUILD/mysql-5.5.40/mysql-5.5.40/storage/myisam/mi_write.c:226

I am using mysql 5.5.40-log and my default storage engine is Innodb, I found this error in my error log "[ERROR] Got an error from unknown thread, ...
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1answer
59 views

Delete and Recreate Indexes in MySQL to reduce table size for copying the db to a new server?

I have to move a given database of 100gb from server a to server b and later this year to server c with a copy for testing to server d. So all servers are Unix (mostly Debian) with MySQL. The ...
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33 views

How to backup huge Mysql db containing both InnoDB & MyISAM tables in Aws RDS?

I am running a Mysql RDS with 150GB+ data. The DB size is growing very fast(But normal considering the application's nature) Till now we were having only InnoDB storage engine, so we were using the ...
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2answers
59 views

Best configuration for MySQL? InnoDB and MyISAM

I read that InnoDB is supposed to be better at writing into MySQL than MyISAM, however, I'm trying it out, by running 3000 MySQL queries(Inserting rows, 8 Columns + id)... but results haven't turned ...
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1answer
54 views

Why MySQL SELECT performance depends on table size? [closed]

I've got two identical tables with the following structure: CREATE TABLE words ( id bigint(20) NOT NULL, `text` int(11) NOT NULL, w1 int(11) NOT NULL, w2 int(11) NOT NULL, w3 int(11) NOT ...
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2answers
36 views

How to define partition according to Date?

I am currently using MySQL 5.6. In my database, I have a log table called paramlog_ems. It has 2M rows I want like to partition this log table according to Date. Here is the table structure: ...
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1answer
360 views

MySQL select by primary key against 100M of records within 30ms

I have no expirience with MySQL and database performance tuning in general. Wondering whether it is possible to perform a large number of selects against 100 millions of records by primary key within ...
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1answer
38 views

MySQL, can't find MYD files on OS X, MAMP

Try as I may I can't find the data files for my MAMP installation! FRM files are here: /Applications/MAMP/db/mysql/database_name/ but, there are no corresponding MYD or MYI files anywhere. The ...
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1answer
48 views

Query databases that have MYISAM tables that do not have only fulltext index tables

I am trying to query from the information_schema where the database (table_schema) has MYISAM tables but does not have only fulltext index tables. The statistics tables is very poorly designed for ...
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2answers
43 views

MySQL - SELECT on MyISAM Table on index - Does table size (rowcount) matter?

I was arguing with a coworker if SELECT * WHERE t BETWEEN ? AND ? on a MyIsam table where t is an index is significantly slower for huge tables. The hypothetically returned dataset is always the ...
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1answer
60 views

how to cache a subset for cascading select queries in mysql

Here is another database problem I stumbled upon. I have a date-range partitioned MyIsam look-up table with 200M records and ~150 columns. On this Table I need to perform cascading SELECT-Statements ...
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9answers
73k views

What are the main differences between InnoDB and MyISAM?

What are the main differences between InnoDB and MyISAM?
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My.cnf tuning for a MySQL Slave [duplicate]

I have a MySQL Slave (MyISAM) where I only run SELECT statements. I would like to have a standard configuration in order to easily duplicate it on new slaves in the future. Currently the my.cnf is ...
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1answer
818 views

MySQL hangs in killed state

I have a strange situation where a mysql OPTIMIZE query will never end. After killinh it, it remains in the "killed" state. Scenario to reproduce: OS: CentOS 6.5 MySQL: 5.6 Engine: MyISAM (with at ...
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1answer
49 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 the dump file into MyISAM-based DB, I got the set of tables without any connections between them via foreign ...
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0answers
2k views

MySQL - high CPU usage (MyISAM tables)

We have a server running LAMP stack on CentOS release 5.6 (Final) MySQL is having high CPU usage constantly which causes server to lag as shown top - 13:50:47 up 80 days, 13:53, 1 user, load ...
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1answer
32 views

Will 'sleeping' connections open files other than the socket in MySQL?

Recently, in our MySQL replication setup, the replication slave crashed due to 'too many open files' error. We brought it backup, but trying to figure out what caused the unexpected hike in the number ...
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251 views

Is searching an alternate index on a partitioned myISAM table concurrent or serial?

I have a myISAM table with 30 partitions. The primary key is a SHA1 hash value, which is also used in the partition selection function. I also have an alternate key - an autoincrement integer. Since ...
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103 views

Complex query performance in MySQL InnoDB versus MyISAM

I am running on MariaDB 10.0.15 on a 4GB RAM cloud server with Local SSD disk for database. My model: users <n---n> right_holders <n---n> tracks ---n> raw_detections I have this ...
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1answer
1k views

Space not reclaimed after dropping MyISAM table

I just dropped a rather large MyISAM table (~4 gb); it was 350k rows with about 11k of data per row. However, when I run df -h on my database server, I am still at 100% disk usage, so much so that I ...
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3answers
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MySQL Table not repairing

Table info: Database name: user_motiva Table name: wp_options.frm wp_options.MYD wp_options.MYI wp_options.TMD when I do a mysqlcheck -r --all-databases it gets hung on that table even if you ...