MySQL random data loader
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Random data generator for MySQL

Build Status

Many times in my job I need to generate random data for a specific table in order to reproduce an issue.
After writing many random generators for every table, I decided to write a random data generator, able to get the table structure and generate random data for it.
Plase take into consideration that this is the first version and it doesn't support all field types yet!

This is an early stage project.

Supported fields:

Field type Generated values
tinyint 0 ~ 0xFF
smallint 0 ~ 0XFFFF
mediumint 0 ~ 0xFFFFFF
int - integer 0 ~ 0xFFFFFFFF
float 0 ~ 1e8
decimal(m,n) 0 ~ 10^(m-n)
double 0 ~ 1000
char(n) up to n random chars
varchar(n) up to n random chars
date NOW() - 1 year ~ NOW()
datetime NOW() - 1 year ~ NOW()
timestamp NOW() - 1 year ~ NOW()
time 00:00:00 ~ 23:59:59
year Current year - 1 ~ current year
tinyblob up to 100 chars random paragraph
tinytext up to 100 chars random paragraph
blob up to 100 chars random paragraph
text up to 100 chars random paragraph
mediumblob up to 100 chars random paragraph
mediumtext up to 100 chars random paragraph
longblob up to 100 chars random paragraph
longtext up to 100 chars random paragraph
varbinary up to 100 chars random paragraph
enum A random item from the valid items list
set A random item from the valid items list

How strings are generated

  • If field size < 10 the program generates a random "first name"
  • If the field size > 10 and < 30 the program generates a random "full name"
  • If the field size > 30 the program generates a "lorem ipsum" paragraph having up to 100 chars.

The program can detect if a field accepts NULLs and if it does, it will generate NULLs ramdomly (~ 10 % of the values).


mysql_random_data_load <database> <table> <number of rows> [options...]


Option Description
--bulk-size Number of rows per INSERT statement (Default: 1000)
--debug Show some debug information
--fk-samples-factor Percentage used to get random samples for foreign keys fields. Default 0.3
--host Host name/ip
--max-fk-samples Maximum number of samples for fields having foreign keys constarints. Default: 100
--max-retries Maximum number of rows to retry in case of errors. See duplicated keys. Deafult: 100
--no-progressbar Skip showing the progress bar. Default: false
--password Password
--port Port number
--Print Print queries to the standard output instead of inserting them into the db
--user Username
--version Show version and exit

Foreign keys support

If a field has Foreign Keys constraints, random-data-load will get up to --max-fk-samples random samples from the referenced tables in order to insert valid values for the field.
The number of samples to get follows this rules:
1. Get the aproximate number of rows in the referenced table using the rows field in:

EXPLAIN SELECT COUNT(*) FROM <referenced schema>.<referenced table>

1.1 If the number of rows is less than max-fk-samples, all rows are retrieved from the referenced table using this query:

SELECT <referenced field> FROM <referenced schema>.<referenced table>

1.2 If the number of rows is greater than max-fk-samples, samples are retrieved from the referenced table using this query:

SELECT <referenced field> FROM <referenced schema>.<referenced table> WHERE RAND() <= <fk-samples-factor> LIMIT <max-fk-samples>



CREATE TABLE `test`.`t3` (
  `tcol01` tinyint(4) DEFAULT NULL,
  `tcol02` smallint(6) DEFAULT NULL,
  `tcol03` mediumint(9) DEFAULT NULL,
  `tcol04` int(11) DEFAULT NULL,
  `tcol05` bigint(20) DEFAULT NULL,
  `tcol06` float DEFAULT NULL,
  `tcol07` double DEFAULT NULL,
  `tcol08` decimal(10,2) DEFAULT NULL,
  `tcol09` date DEFAULT NULL,
  `tcol10` datetime DEFAULT NULL,
  `tcol12` time DEFAULT NULL,
  `tcol13` year(4) DEFAULT NULL,
  `tcol14` varchar(100) DEFAULT NULL,
  `tcol15` char(2) DEFAULT NULL,
  `tcol16` blob,
  `tcol17` text,
  `tcol18` mediumtext,
  `tcol19` mediumblob,
  `tcol20` longblob,
  `tcol21` longtext,
  `tcol22` mediumtext,
  `tcol23` varchar(3) DEFAULT NULL,
  `tcol24` varbinary(10) DEFAULT NULL,
  `tcol25` enum('a','b','c') DEFAULT NULL,
  `tcol26` set('red','green','blue') DEFAULT NULL,
  `tcol27` float(5,3) DEFAULT NULL,
  `tcol28` double(4,2) DEFAULT NULL,
  PRIMARY KEY (`id`)

To generate 100K random rows, just run:

mysql_random-data-load test t3 100000 --user=root --password=root
mysql> select * from t3 limit 1\G
*************************** 1. row ***************************
    id: 1
tcol01: 10
tcol02: 173
tcol03: 1700
tcol04: 13498
tcol05: 33239373
tcol06: 44846.4
tcol07: 5300.23
tcol08: 11360967.75
tcol09: 2017-09-04
tcol10: 2016-11-02 23:11:25
tcol11: 2017-03-03 08:11:40
tcol12: 03:19:39
tcol13: 2017
tcol14: repellat maxime nostrum provident maiores ut quo voluptas.
tcol15: Th
tcol16: Walter
tcol17: quo repellat accusamus quidem odi
tcol18: esse laboriosam nobis libero aut dolores e
tcol19: Carlos Willia
tcol20: et nostrum iusto ipsa sunt recusa
tcol21: a accusantium laboriosam voluptas facilis.
tcol22: laudantium quo unde molestiae consequatur magnam.
tcol23: Pet
tcol24: Richard
tcol25: c
tcol26: green
tcol27: 47.430
tcol28: 6.12
1 row in set (0.00 sec)

How to download the precompiled binaries

There are binaries available for each version for Linux and Darwin. You can find compiled binaries for each version in the releases tab:

To do

  • Add suport for all data types.
  • Add supporrt for foreign keys.
  • Support config files to override default values/ranges.
  • Support custom functions via LUA plugins.

Version history


  • Fixed connection parameters for MySQL 5.7 (set driver's AllowNativePasswords: true)


  • Added support for bunary and varbinary columns
  • By default, read connection params from ${HOME}/.my.cnf


  • Fixed error for triggers created with MySQL 5.6
  • Added Travis-CI
  • Code clean up


  • Support for MySQL 8.0
  • Added --print parameter
  • Added --version parameter
  • Removed qps parameter


  • Improved generation speed (up to 50% faster)
  • Improved support for TokuDB (Thanks Agustin Gallego)
  • Code refactored
  • Improved debug logging
  • Added Query Per Seconds support (experimental)


  • Fixed handling of NULL collation for index parser


  • Fixed handling of time columns
  • Improved support of GENERATED columns


  • Fixed handling of nulls


  • New table parser able to retrieve all the information for fields, indexes and foreign keys constraints.
  • Support for foreign keys constraints
  • Added some tests


  • Fixed random data generation


  • Initial version