nmig/README.md

NMIG - the database migration tool.

WHAT IS IT ALL ABOUT?

NMIG is an app, intended to make a process of migration from MySQL to PostgreSQL as easy and smooth as possible.

KEY FEATURES

• Ease of use - the only thing needed to run this app is the Node.js runtime.
• Accuracy of migration the database structure - NMIG converts MySQL data types to corresponding PostgreSQL data types, creates constraints, indexes, primary and foreign keys exactly as they were before migration.
• Ability to migrate big databases - in order to reduce RAM consumption NMIG will split each table's data into several chunks.
  Chunk size can be adjusted easily via configuration file.
• Speed of data transfer - in order to migrate data fast NMIG uses PostgreSQL COPY protocol.
  Note: migration of tables, containing "varbinary" or "blob" columns may be considerably slower.
• Ease of monitoring - NMIG will provide detailed output about every step, it takes during the execution.
• Ease of configuration - all the parameters required for migration should be put in one single JSON document.

SYSTEM REQUIREMENTS

• Node.js 5.x.x

USAGE

1. Create a new database.
Sample: 

 CREATE DATABASE my_postgresql_database;

2. Download NMIG package and put it on the machine running your PostgreSQL.
Sample: 

 /path/to/nmig

3. Edit configuration file located at

/path/to/nmig/config.json

with correct details.

Note:  config.json contains brief description of each configuration parameter.

4.Go to nmig directory, install dependencies, and run the app.
    Sample:

$ cd /path/to/nmig

$ npm install mysql

$ npm install pg

$ node main.js

5. At the end of migration check log files, if necessary.
    Log files will be located under "logs_directory" folder in the root of the package.
    Note: "logs_directory" will be created during script execution.

6. In case of any remarks, misunderstandings or errors during migration,
    please feel free to email me anatolyuss@gmail.com

VERSION

Current version is 1.0.0
(major version . improvements . bug fixes)

TEST

Tested using MySQL Community Server (5.6.21) and PostgreSQL (9.3).
The entire process of migration 59.6 MB database (52 tables, 570754 rows),
which includes data types mapping, creation of tables, constraints, indexes,
PKs, FKs, migration of data, garbage-collection (VACUUM) and analyzing the newly created
PostgreSQL database took 1 minute 18 seconds.

Remark:  it is highly recommended to VACUUM newly created database!
Just keep in mind, that VACUUM is a very time-consuming procedure.
So if you are short in time - disable VACUUM via config.json ("no_vacuum" parameter).
Such step will save you ~25% of migration time.
The migration process described above without VACUUM took 58 seconds only.

LICENSE

NMIG is available under "GNU GENERAL PUBLIC LICENSE" (v. 3)
http://www.gnu.org/licenses/gpl.txt.

REMARKS

Errors/Exceptions are not passed silently.
Any error will be immediately written into the error log file.