Introduction

pgloader loads data from various sources into PostgreSQL. It can transform the data it reads on the fly and submit raw SQL before and after the loading. It uses the COPY PostgreSQL protocol to stream the data into the server, and manages errors by filling a pair of reject.dat and reject.log files.

pgloader knows how to read data from different kind of sources:

  • Files
    • CSV
    • Fixed Format
    • DBF
  • Databases
    • SQLite
    • MySQL
    • MS SQL Server
    • PostgreSQL
    • Redshift

pgloader knows how to target different products using the PostgresQL Protocol:

  • PostgreSQL
  • Citus
  • Redshift

The level of automation provided by pgloader depends on the data source type. In the case of CSV and Fixed Format files, a full description of the expected input properties must be given to pgloader. In the case of a database, pgloader connects to the live service and knows how to fetch the metadata it needs directly from it.

Continuous Migration

pgloader is meant to migrate a whole database in a single command line and without any manual intervention. The goal is to be able to setup a Continuous Integration environment as described in the Project Methodology document of the MySQL to PostgreSQL webpage.

  1. Setup your target PostgreSQL Architecture
  2. Fork a Continuous Integration environment that uses PostgreSQL
  3. Migrate the data over and over again every night, from production
  4. As soon as the CI is all green using PostgreSQL, schedule the D-Day
  5. Migrate without suprise and enjoy!

In order to be able to follow this great methodology, you need tooling to implement the third step in a fully automated way. That’s pgloader.

Commands

pgloader implements its own Command Language, a DSL that allows to specify every aspect of the data load and migration to implement. Some of the features provided in the language are only available for a specific source type.

Command Line

The pgloader command line accepts those two variants:

pgloader [<options>] [<command-file>]...
pgloader [<options>] SOURCE TARGET

Either you have a command-file containing migration specifications in the pgloader Command Language, or you can give a Source for the data and a PostgreSQL database connection Target where to load the data into.