Random data generator for MySQL and PostgreSQL

Forked from https://github.com/Percona-Lab/mysql_random_data_load

This tool aims to produce a quick working environment to reproduce a query execution behavior in order to optimize it. It is meant for cases where we cannot access real data, only schema and cardinalities.

Based on the table(s) schema and a query, it will generate random data with respect to fields, foreign keys defined in databases, foreign keys infered from the query pattern, (plan: from existing cardinalities and distributions).

Notice: This is early stage

Usage

random-data-load run --engine=(mysql|pg) --rows=INT-64 (--query=SELECT ...|--table=table_name) [options...]

Supported fields:

Field type	Generated values
bool	false ~ true
tinyint	0 ~ 0xFF
smallint	0 ~ 0XFFFF
mediumint	0 ~ 0xFFFFFF
int - integer	0 ~ 0xFFFFFFFF
bigint	0 ~ 0xFFFFFFFFFFFFFFFF
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 --max-text-size chars random paragraph
text	up to --max-text-size chars random paragraph
mediumblob	up to --max-text-size chars random paragraph
mediumtext	up to --max-text-size chars random paragraph
longblob	up to --max-text-size chars random paragraph
longtext	up to --max-text-size chars random paragraph
enum	A random item from the valid items list
set	A random item from the valid items list

Options

Option	Description
--engine	mysql/pg
--host	Host name/ip
--user	Username
--password	Password
--port	Port number
--bulk-size	Number of rows per INSERT statement (Default: 1000)
--workers	how many workers to spawn. Only the random generation and sampling are parallelized. Insert queries are executed one at a time (Default: 3)
--table	Table to insert to. When using --query, --table will be used to restrict the tables to insert to.
--query	Providing a query will analyze its schema usage, insert recursively into tables, and identify implicit joins
--default-relationship	Will define the default foreign-key relationship to apply. Possible values: binomial,1-1. The default relation can be overriden with other parameters --binomial or --1-1
--binomial	Defines a 1-N foreign key relationships using repeated coin flips. Postgres' tablesamples Bernouilli or mysql RAND() < 0.1 (can be tuned with --coin-flip-percent). E.g: --binomial="customers=orders;orders=items"
--coin-flip-percent	When used with --binomial, it will set the likeliness of each rows to be sampled or not. 10 would mean each rows have only 10%% chance to be selected when sampling a parent table. Using large values will favor hot rows: the coin flips are done with a table full scan, with a limit set at --bulk-size, so with a large percent chance most of the time the first rows will be selected. No effects when used with --1-1 (Default: 10)
--1-1	Defines a 1-1 foreign key links relationships. E.g: --1-1="citizens=ssns"
--virtual-foreign-keys	Add foreign keys, if they are not explicitely created in the table schema. The format must be parent_table.col1=child_table.col2. It will overwrite every foreign keys guessed from the --query. Example --virtual-foreign-keys="customers.id=purchases.customer_id;purchases.id=items.purchase_id"
--skip-auto-virtual-foreign-keys	Disable foreign key autocomplete. When a query is provided, it will analyze the expected JOINs and try to respect dependencies even when foreign keys are not explicitely created in the database objects. This flag will make the tool stick to the constraints defined in the database only.
--quiet	Do not print progress bar
--dry-run	Print queries to the standard output instead of inserting them into the db
--debug	Show some debug information
--pprof	Generate pprof trace at --cpu-prof-path. Also opens port 6060 for pprof go tool
--version	Show version and exit

Foreign keys support

If a field has Foreign Keys constraints, random-data-load will get samples from the referenced tables in order to insert valid values for the field.

Compounds foreign keys are supported. With very low chances to sample rows, we might sample too little. The tool will loop until it sampled enough rows to fill the next bulk insert.

1. 1-1 relationships will sample with LIMIT and OFFSET:

SELECT <field[, field2]> FROM <referenced schema>.<referenced table> LIMIT <--bulk-size> OFFSET y

This isn't the fastest method but it works for every types. The value of the current OFFSET is protected by mutex to prevents frequent duplicates, however there are currently no ORDER BYs to truly secure against re-using samples.

2. binomial relations will sample differently between postgres and mysql

2.1 For postgres it relies on TABLESAMPLE

SELECT <field[, field2]> FROM <referenced schema>.<referenced table> TABLESAMPLE BERNOUILLI (<--coin-flip-percent>) LIMIT <--bulk-size>

2.2 For mysql, it relies on RAND()

SELECT <field[, field2]> FROM <referenced schema>.<referenced table> WHERE rand() < (<--coin-flip-percent>/100) LIMIT <--bulk-size>

Guessing implicit foreign keys from queries

If no foreign keys are explicitely defined in the schema, but the query is using JOINs with a "ON" clause, random-data-load will infer the foreign keys and insert valid values so that JOINs work.

An estimation can be made using:

random-data-load query --query="$(cat huge_select.sql)"

It will skip guessing foreign keys for those cases:

• JOINs relying on subqueries instead of tables
• JOINs made implicitely without JOIN keywords or "ON" clauses
• (limitation) JOINs having its ON clause between parenthesis are currently thought to be subqueries and are skipped
• JOINs conditions using ambiguous columns, without expliciting to what table it belongs. Example FROM x JOIN y ON apple=pear instead of FROM x JOIN y ON x.apple=y.pear

Example

CREATE DATABASE IF NOT EXISTS test;

CREATE TABLE `test`.`t3` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `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,
  `tcol11` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `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`)
) ENGINE=InnoDB;

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:

https://github.com/Percona-Lab/random-data-load/releases

To do

• better datetime random generation. It should be flexible over its range
• helpers to get schema (generate pgdump/mysqldump commands, get index stats, ...)
• import col/index stats and reproduce data distribution

Version history

0.2.0

• Support for postgres
• parallelism
• bool types
• uniform foreign key patterns
• skipping unecessary columns and backfilling missing foreign keys through query analysis

0.1.10

• Fixed argument validations
• Fixed ~/.my.cnf loading

0.1.10

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

0.1.9

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

0.1.8

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

0.1.7

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

0.1.6

• 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)

0.1.5

• Fixed handling of NULL collation for index parser

0.1.4

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

0.1.3

• Fixed handling of nulls

0.1.2

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

0.1.1

• Fixed random data generation

0.1.0

• Initial version