Questions tagged [myisam]

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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182 views

MySQL CREATE INDEX slowing down

My analytics table has 190M rows, about 150GB ins size. Storage engine is MyISAM with key-buffer-size=16G myisam_sort_buffer_size=2G myisam-max-sort-file-size=200G. Machine has 32GB memory. While ...
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Using xtrabackup backup to recover MyISAM data

Why do I have a ibdata1 file when backing up MyISAM data? I don't have a InnoDB table. I can't find anything about recovering MyISAM data on the official website. How Do Irestore a single backup of ...
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How to change default engine in WAMP to InnoDB

Can someone tell me how to change my default storage engine to InnoDB using wamp? Currently it is MyISAM.
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Change all table ENGINE at once from “MyISAM” to “InnoDB” in MySql with single query

I had some foreign key issues in my database when I change the table engine "MyISAM" to "InnoDB" then it gets working fine. I found one query to change the table engine but I had lots of tables so is ...
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Can I extrapolate from the progress reporting in MyISAM ALTER?

I'm migrating a 300 million row MyISAM table to add some indexes. Just because it might be relevant, here's my ALTER statement: ALTER TABLE my_table ADD UNIQUE INDEX my_table_abcd (a, b, c, d), ...
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Mysql separate username from client table for performance and use myisam for it

I'm creating a database for a very heavy messenger like Telegram ... I decided to use a different table for client-username and separate it from the clients table. This is My 'client' table: InnoDB ...
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78 views

MYSQL Multiple table optimization for advanced search

I have a users table where there is the basic information of each user: CREATE TABLE `users` ( `user_id` int(11) NOT NULL AUTO_INCREMENT, `account_type` varchar(10) NOT NULL, `email` varchar(...
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123 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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C API hangs in mysql_query()

I have this very strange issue and I cannot reproduce it - it occurs once in ~12 hours only for this table: CREATE TABLE `ReferenceWaves` ( `ReferenceWave` datetime NOT NULL COMMENT 'DateTime of ...
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Finding temporary table name in MariaDB

As I reported some days ago to MariaDB bug tracker the following bug: https://jira.mariadb.org/browse/MDEV-17420, slave replicas with version 10.2.x are leaking temporary tables on MyISAM files. Our ...
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Using MyISAM for reading and InnoDB for writing data

I read many articles about comparisons of MyISAM and InnoDB from performance point of view and I decided to use MyISAM for reading data and InnoDB for writing data. I want to use two structure like ...
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MySQL 5.6 row format changes when changing storage engine from MyISAM to InnoDB

I am testing an upgrade of all existing MySQL 5.6 tables from MyISAM to InnoDB. I converted all row formats to dynamic first for all the tables to be on Barracuda then running alter table <...
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157 views

Proper Way to Remove Mysql Tables

I was going to ask why mysqldump was trying to write dropped tables but I found that answer from this question, How do you remove reported non existing tables from mysql?. Removing the .frm files ...
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84 views

Convert table from MyISAM to InnoDB and keep MyISAM rows order

I'm currently rewriting old project and I've got this strange scenario. It's an online store, it has products with images. The images are stored in separate table. Here is example query. The part ...
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Explain plan : Why rows examined higher in this cased? [duplicate]

I have 450 million records in my table which contains the data for around 7 to 8 months. So per month data is around 60 million records. Table has index on empDate. When I execute below query , I ...
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181 views

Change Storage Engine on Referenced Tables

i need to change storage engine from 'InnoDB' to 'MyISAM' on some tables of different databases. So i made a script file to do so: #!/bin/bash DATABASES=$(mysql -u XXXXX -pXXXXX --skip-column-names -...
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MySQL MyIsam Compressing tables

Im packing big MyISAM tables with myisampack and came up with the following issue. (MariaDB 10.1.14 64bit windows) Indexes are rebuilt after packing the tablewhile running myisamchk -rq, so, it doesnt ...
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Much slower replication on Innodb compared to myisam

Good morning. I wanted to test how InnoDB will work on my servers and for this I made a slave and connected it to my master with myisam. The problem is that when the slave works on innodb, replication ...
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Strange MySQL replication error 1146 (Table doesn't exist)

I'm getting a very weird MySQL replication error No. 1146 for a REPLACE INTO query on a slave host replicating all tables in all databases from a master, and I'm having a bit of a hard time ...
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From MySQL to MariaDB : bad performances issue with MyISAM tables

I'm currently migrating a Debian 6 MySQL server (5.1.73) to a fresh new Debian 10 MariaDB server (10.3.18). Please note that I'm not a database expert. All tables are under MyISAM engine storage, for ...
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Inserts in MySQL 8 are slower than Inserts in MySQL 5.7

I've started to use MySQL 8 (8.0.12), and I'm realizing that the "inserts" are slower in this version than MySQL 5.6 or MySQL 5.7. It doesn't matter if the table is MyISAM or InnoDB, with just one "...
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601 views

Repair by Sort not working

I am trying to import a .sql file which has MyISAM engine, about 51 million rows with 18 columns. The file has 1 primary and 1 unique key. I have after lurking around this site and reading mysql ...
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MariaDB 10.3: InnoDB much slower than MyISAM

I'm using MariaDB 10.3.12 on Arch Linux and haven't modified any of the default settings under /etc/mysql. The following script takes 0.75 s to run on average using the default InnoDB engine: drop ...
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394 views

Safe method to rename a crashed myisam table

I have a large MyISAM table which has crashed. Repairing the table will take some time. The table only INSERTed to and SELECTed from, never updated. To allow the application to continue working, ...
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579 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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troubleshooting mysqlimport very large text file

I've been attempting to import a very large (390 GiB) text file using the mysqlimport client. I've been successful at importing a 14 GiB text file as well as numerous smaller files using this method. ...
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607 views

MySQL MyISAM REPAIR TABLE lost connection to MySQL server during query

So I've been building up over time a database, and unfortunately I was using MyISAM which didn't have any problems until the database became huge. After massive CPU spikes, I created a script to ...
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2answers
738 views

Mysql SHOW OPEN TABLES shows In_use but nothing in SHOW PROCESSLIST

I'm looking for advice for a MySQL database used for my development. I have a table is locked, although no process is active. Here's some context: I am a developer on this MySQL development database ...
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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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517 views

Extremely slow MyISAM slave updates

I have 2 slaves where one is working as expected, but the other slave is extremely slow when executing update statements. The insert and delete statements are fast. I used the command check table ...
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14k 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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Changed MyISAM to InnoDB, huge performance loss [closed]

So I'm testing on our dev server to change MyISAM to InnoDB and am having a huge performance loss. Here is my.cnf: innodb_file_per_table=1 innodb_flush_method=O_DIRECT innodb_buffer_pool_instance=2 ...
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1answer
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MySQL: error 1118 (42000) row size too large

storage_engine = MyISAM table_type = MyISAM version = 5.1.25-rc database_name.sql dump size is 3.3G: mysqldump -u user -p database_name > database_name.sql When I try to restore the database (...
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Disk full of mysql .mad and .mai files

On a (owned) shared server sometimes mysql writes alott of .mad and .mai. This happens since i think 2 or 3 months, completely random. It may happen 3 times a day, then it does not happen for a ...
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How to determine the optimal sort_buffer_size?

I read from a sample configuration file which says the following: # Sort buffer is used to perform sorts for some ORDER BY and GROUP BY # queries. If sorted data does not fit into the sort buffer, a ...
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Table column length is fine in MySQL 5.5 and 5.6, but upgrading to 5.7 results in too many columns

So I have a CMS that is being upgraded from MySQL 5.5 -> 5.7. One table has a 1000+ columns, but it works fine in 5.5 and 5.6. When reaching 5.7, queries involving this table result in a 1117 error. (...
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How to repair mysql tables using myisam storage engine from multiple repairing threads?

I am loading a csv file into a mysql database table that uses MyISAM as storage engine. From the process list I can see that this is accomplished in two phases: 1) reading the csv file and 2) ...
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Table metadata lock MariaDB

I'm having serious problems in a DB, where a "Waiting for table level lock" box is loitering and locks the whole system: Based on some research, when the problem occurred to get the command "SELECT * ...
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112 views

InnoDB errors and crashes with MyISAM database?

I have one server with one mysql database containing only MyISAM tables. There is no other databases on the server (except system ones of course). Since it moved to mysql 5.7.27 there are InnoDB ...
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MySQL: optimal configs / methods for ALTER of large MyISAM table to InnoDB (17gb+)

I have a large MySQL (5.1) MyISAM table (13gb table, 4GB indexes - 40mm+ records) I'm going to be converting this table to InnoDB in a production environment. The DB is on a cloud server with 8GB ...
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How to copy a MySQL database which is a mixture of InnoDB and MyISAM to the same server?

Because mysqldump takes forever, we decided to just move around the files. Because the 2 databases are on the same server, a cp will be fast. The problem is, from research, MyISAM is okay with being ...
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1answer
778 views

Upgrading mysql myisam 5.1 to mysql 5.6: force innodb on restore?

I inherited a DB using myisam on mysql 5.1 because of the need for fulltext search. I now read that fulltext search is available on mysql 5.6 innodb. Doing this would solve a lot of problems, as long ...
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Benefits of table level locking

What are the benefits of table level locking which is used by the MyISAM storage engine? Row level locking has lots of benefits like concurrent updates and reads that do not lock the table. Edit Its ...
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Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
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Why does MySQL produce so many temporary MYD files?

On a Debian Linux server, hosting many PHP/MySQL websites (photo galleries), sometimes I have "many" files like /tmp/#sql_6405_58.MYD. For example today : [2012-12-15 15:18:11] /tmp/#sql_6405_6.MYD :...
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MySQL: Is it safe to set `key_buffer_size` to 0 if the db doesn't have any MyISAM table?

In our system, we don't use MyISAM - only InnoDB (and occasionally, MEMORY). Is it safe to set key_buffer_size to 0? Or there are unexpected side effects? Based on the manual, it seems it's safe.
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Duplicate table names after restoring a backup

I got this weird issue today when I restored a full .sql backup from one server to another server using dbForge Studio for MySQL (third party software). Both are having same properties like table ...
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1answer
286 views

Will too many tables slow Mysql down?

I'm making a database which should be able to handle over 1,000,000,000 rows. in order to optimize it's performance i've decided to split tables. so instead of having 1,000,000,000 entries in one ...
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How to safely change MySQL innodb variable 'innodb_log_file_size'?

So I'm fairly new to tuning InnoDB. I'm slowly changing tables (where necessary) from MyIsam to InnoDB. I've got about 100MB in innodb, so I increased the innodb_buffer_pool_size variable to 128MB: ...
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136 views

Make Xtrabackup ignore myisam tables & backup only innoDB tables?

I'm using mysql 5.7 (or rather percona 5.7) Is it possible to backup only the innodb tables (easily, not to specify each table one by one because I have a lot of tables) with xtrabackup? and not take ...

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