Cheater - Generate random database based on rules
This document describes Cheater 0.10 released on June 24, 2011.
Cheater is a tool that can generate random database based on rules. It was widely used within the LineZing team of Taobao.com.
Compared to other similar tools, cheater has the following advantages:
- it can automatically handle the association and foreign key restrictions among data tables, so it's the real "database instance generator".
- It defines a SQL-like little language to specify the data model that we want to generate from.
- It supports powerful
{a, b, c}discrete enumation sets, numerical/time/date interval syntaxa..b, Perl regular expressions/regex/, constant values'string',1.32, and etc, to describe the value range of data table field. - It can generate JSON or SQL insert statements to ease importing to RDMBSes like MySQL/PostgreSQL.
Below is a very simple example to demonstrate its basic usage.
First of all, we create a .cht input file in our working directory (say, under ~/work/),
in order to describe the data model that we want to geneate data from. Assuming we have
a company.cht file like this:
# Empolyee table
table employees (
id serial;
name text /[A-Z]a-z{2,5} [A-Z]a-z{2,7}/ not null unique;
age integer 18..60 not null;
tel text /1[35]8\d{8}/;
birthday date;
height real 1.50 .. 1.90 not null;
grades text {'A','B','C','D','E'} not null;
department references departments.id;
)
# Department table
table departments (
id serial;
name text /\w{2,10}/ not null;
)
10 employees;
2 departments;
Here we're using the little language (or DSL) defined by cheater itself. It's semantics
is self-explanatory. In particular, the last two lines state that we want to generate 10 rows
of data for the employees table and 2 rows for the departments table.
And then, we use the cht-compile command to compile our company.cht file to generate a
random database instance:
$ cht-compile company.cht
Wrote ./data/departments.schema.json
Wrote ./data/departments.rows.json
Wrote ./data/employees.schema.json
Wrote ./data/employees.rows.json
We see that it generates two .json data files for the departments and employees tables,
respectively. For example, the data/emplyees.rows.json file on my machine resulting from
a particular run looks like this:
$ cat data/employees.rows.json
[["id","name","age","tel","birthday","height","grades","department"],
["7606","Kxhwcn Cflub",54,"15872171866","2011-04-01","1.67276","D","408862"],
["63649","Whf Iajgw",55,"13850771916",null,"1.65297","E","844615"],
["348161","Nnwe Obfkln",27,"15801601215","2011-03-06","1.69275","D","408862"],
["353404","Shgpak Xvqxw",28,"15816453097",null,"1.67796","A","408862"],
["445500","Bdt Mhepht",47,"13855517847",null,"1.89943","C","844615"],
["513515","Ipsa Mcbtk",25,"13874017694","2011-01-06","1.79534","A","844615"],
["658009","Lboe Etqo",27,null,"2011-04-14","1.85162","E","408862"],
["716899","Gey Elacflr",18,"15804516095","2011-02-27","1.75681","A","844615"],
["945911","Hsuz Qcmky",39,"13862516775","2011-05-31","1.75947","B","408862"],
["960643","Qbmbe Ijnbqsb",24,"15872418765","2011-04-11","1.78864","B","844615"]]
These are the "row data". On the other hand, ./data/employees.schema.json is the table structure
definition for the employees table. It looks like this on my side:
[{"attrs":[],"name":"id","type":"serial"},
{"attrs":["not null","unique"],"name":"name","type":"text"},
{"attrs":["not null"],"name":"age","type":"integer"},
{"attrs":[],"name":"tel","type":"text"},
{"attrs":[],"name":"birthday","type":"date"},
{"attrs":["not null"],"name":"height","type":"real"},
{"attrs":["not null"],"name":"grades","type":"text"},
{"attrs":[],"name":"department","type":"serial"}]
We can generate SQL DDL statement files accepted by RDBMSes like MySQL or PostgreSQL from the
.schema.json files like this:
$ cht-schema2sql data/employees.schema.json
Wrote ./sql/employees.schema.sql
The output .sql file looks like this:
$ cat ./sql/employees.schema.sql
drop table if exists employees;
create table employees (
id serial primary key,
name text not null unique,
age integer not null,
tel text,
birthday date,
height real not null,
grades text not null,
department serial
);
If we want to eliminate the drop table statement in the resulting SQL file, we can
specify the -n option while running the cht-schema2sql utility. For instance,
$ cht-schema2sql -n data/employees.schema.json
Wrote ./sql/employees.schema.sql
At last, we can use the cht-rows2sql command to convert those .rows.json data files to
.sql files that are ready for relation database systems to import the "row data".
$ cht-rows2sql data/*.rows.json
Wrote ./sql/departments.rows.sql
Wrote ./sql/employees.rows.sql
The sql/departments.rows.sql looks like this on my side:
$ cat sql/departments.rows.sql
insert into departments (id,name) values
(408862,'dJRq7LCXL'),
(844615,'G_m9Nkh3q');
To prevent the resulting data from conflicting with extra unique key restrictions in the targeting
RDMBS table, we can use the -r option to make cht-rows2sql generate SQL replace statements
to work-around this:
$ cht-rows2sql -r data/*.rows.json
Wrote ./sql/departments.rows.sql
Wrote ./sql/employees.rows.sql
Now we're ready to import the random data into database systems like MySQL!
$ mysql -u some_user -p dbname < sql/departments.rows.sql
For now, cheater is still in active development and lacking comprehensive documentation,
the most complete documentation is its (declarative) test suite:
http://github.com/agentzh/cheater/tree/master/t/
Open one of those .t files, you can see lots of declarative test cases, like these:
=== TEST 5: datetime range domain
--- src
table cats (
birthday datetime 2010-05-24 03:45:00..2010-06-05 18:46:05 not null;
)
5 cats;
--- out
cats
birthday
2010-06-02 14:59:02
2010-06-04 03:31:00
2010-06-03 01:51:41
2010-05-28 19:29:34
2010-06-02 13:31:38
Currently we require at most perl 5.12.x and at least perl 5.10.1. Neither newer nor older versions of perl will not work.
perl Makefile.PL
make
make test
make install
The source repository of this project is on GitHub:
http://github.com/agentzh/cheater/
If you have found any bugs or feature request, feel free to create tickets on the GitHub issues page:
http://github.com/agentzh/cheater/issues
Yichun "agentzh" Zhang (章亦春) <[email protected]>, CloudFlare Inc.
Copyright (c) 2010-2016, Yichun Zhang (agentzh), CloudFlare Inc.
This module is licensed under the terms of the BSD license.
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