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https://github.com/ankane/pgsync

Sync data from one Postgres database to another
https://github.com/ankane/pgsync

postgresql

Last synced: about 2 months ago
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Sync data from one Postgres database to another

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# pgsync



Sync data from one Postgres database to another (like `pg_dump`/`pg_restore`). Designed for:



- **speed** - tables are transferred in parallel

- **security** - built-in methods to prevent sensitive data from ever leaving the server

- **flexibility** - gracefully handles schema differences, like missing columns and extra columns

- **convenience** - sync partial tables, groups of tables, and related records



:tangerine: Battle-tested at [Instacart](https://www.instacart.com/opensource)



[![Build Status](https://github.com/ankane/pgsync/actions/workflows/build.yml/badge.svg)](https://github.com/ankane/pgsync/actions)



## Installation



pgsync is a command line tool. To install, run:



```sh

gem install pgsync

```



This will give you the `pgsync` command. If installation fails, you may need to install [dependencies](#dependencies).



You can also install it with Homebrew:



```sh

brew install pgsync

```



## Setup



In your project directory, run:



```sh

pgsync --init

```



This creates `.pgsync.yml` for you to customize. We recommend checking this into your version control (assuming it doesn’t contain sensitive information). `pgsync` commands can be run from this directory or any subdirectory.



## How to Use



First, make sure your schema is set up in both databases. We recommend using a schema migration tool for this, but pgsync also provides a few [convenience methods](#schema). Once that’s done, you’re ready to sync data.



Sync tables



```sh

pgsync

```



Sync specific tables



```sh

pgsync table1,table2

```



Works with wildcards as well



```sh

pgsync "table*"

```



Sync specific rows (existing rows are overwritten)



```sh

pgsync products "where store_id = 1"

```



You can also preserve existing rows



```sh

pgsync products "where store_id = 1" --preserve

```



Or truncate them



```sh

pgsync products "where store_id = 1" --truncate

```



## Tables



Exclude specific tables



```sh

pgsync --exclude table1,table2

```



Add to `.pgsync.yml` to exclude by default



```yml

exclude:

  - table1

  - table2

```



Sync tables from all schemas or specific schemas (by default, only the search path is synced)



```sh

pgsync --all-schemas

# or

pgsync --schemas public,other

# or

pgsync public.table1,other.table2

```



## Groups



Define groups in `.pgsync.yml`:



```yml

groups:

  group1:

    - table1

    - table2

```



And run:



```sh

pgsync group1

```



## Variables



You can also use groups to sync a specific record and associated records in other tables.



To get product `123` with its reviews, last 10 coupons, and store, use:



```yml

groups:

  product:

    products: "where id = {1}"

    reviews: "where product_id = {1}"

    coupons: "where product_id = {1} order by created_at desc limit 10"

    stores: "where id in (select store_id from products where id = {1})"

```



And run:



```sh

pgsync product:123

```



## Schema



Sync the schema before the data (this wipes out existing data)



```sh

pgsync --schema-first

```



Specify tables



```sh

pgsync table1,table2 --schema-first

```



Sync the schema without data (this wipes out existing data)



```sh

pgsync --schema-only

```



pgsync does not try to sync Postgres extensions.



## Sensitive Data



Prevent sensitive data like email addresses from leaving the remote server.



Define rules in `.pgsync.yml`:



```yml

data_rules:

  email: unique_email

  last_name: random_letter

  birthday: random_date

  users.auth_token:

    value: secret

  visits_count:

    statement: "(RANDOM() * 10)::int"

  encrypted_*: null

```



`last_name` matches all columns named `last_name` and `users.last_name` matches only the users table. Wildcards are supported, and the first matching rule is applied.



Options for replacement are:



- `unique_email`

- `unique_phone`

- `unique_secret`

- `random_letter`

- `random_int`

- `random_date`

- `random_time`

- `random_ip`

- `value`

- `statement`

- `null`

- `untouched`



Rules starting with `unique_` require the table to have a single column primary key. `unique_phone` requires a numeric primary key.



## Foreign Keys



Foreign keys can make it difficult to sync data. Three options are:



1. Defer constraints (recommended)

2. Manually specify the order of tables

3. Disable foreign key triggers, which can silently break referential integrity (not recommended)



To defer constraints, use:



```sh

pgsync --defer-constraints

```



To manually specify the order of tables, use `--jobs 1` so tables are synced one-at-a-time.



```sh

pgsync table1,table2,table3 --jobs 1

```



To disable foreign key triggers and potentially break referential integrity, use:



```sh

pgsync --disable-integrity

```



This requires superuser privileges on the `to` database. If syncing to (not from) Amazon RDS, use the `rds_superuser` role. If syncing to (not from) Heroku, there doesn’t appear to be a way to disable integrity.



## Triggers



Disable user triggers with:



```sh

pgsync --disable-user-triggers

```



## Sequences



Skip syncing sequences with:



```sh

pgsync --no-sequences

```



## Append-Only Tables



For extremely large, append-only tables, sync in batches.



```sh

pgsync large_table --in-batches

```



Note: This requires the table to have a numeric, increasing primary key



The script will resume where it left off when run again, making it great for backfills.



## Connection Security



Always make sure your [connection is secure](https://ankane.org/postgres-sslmode-explained) when connecting to a database over a network you don’t fully trust. Your best option is to connect over SSH or a VPN. Another option is to use `sslmode=verify-full`. If you don’t do this, your database credentials can be compromised.



## Safety



To keep you from accidentally overwriting production, the destination is limited to `localhost` or `127.0.0.1` by default.



To use another host, add `to_safe: true` to your `.pgsync.yml`.



## Multiple Databases



To use with multiple databases, run:



```sh

pgsync --init db2

```



This creates `.pgsync-db2.yml` for you to edit. Specify a database in commands with:



```sh

pgsync --db db2

```



## Integrations



- [Django](#django)

- [Heroku](#heroku)

- [Laravel](#laravel)

- [Rails](#rails)



### Django



If you run `pgsync --init` in a Django project, migrations will be excluded in `.pgsync.yml`.



```yml

exclude:

  - django_migrations

```



### Heroku



If you run `pgsync --init` in a Heroku project, the `from` database will be set in `.pgsync.yml`.



```yml

from: $(heroku config:get DATABASE_URL)?sslmode=require

```



### Laravel



If you run `pgsync --init` in a Laravel project, migrations will be excluded in `.pgsync.yml`.



```yml

exclude:

  - migrations

```



### Rails



If you run `pgsync --init` in a Rails project, Active Record metadata and schema migrations will be excluded in `.pgsync.yml`.



```yml

exclude:

  - ar_internal_metadata

  - schema_migrations

```



## Debugging



To view the SQL that’s run, use:



```sh

pgsync --debug

```



## Other Commands



Help



```sh

pgsync --help

```



Version



```sh

pgsync --version

```



List tables



```sh

pgsync --list

```



## Scripts



Use groups when possible to take advantage of parallelism.



For Ruby scripts, you may need to do:



```rb

Bundler.with_unbundled_env do

  system "pgsync ..."

end

```



## Docker



Get the [Docker image](https://hub.docker.com/r/ankane/pgsync) with:



```sh

docker pull ankane/pgsync

alias pgsync="docker run -ti ankane/pgsync"

```



This will give you the `pgsync` command.



## Dependencies



If installation fails, your system may be missing Ruby or libpq.



On Mac, run:



```sh

brew install libpq

```



On Ubuntu, run:



```sh

sudo apt-get install ruby-dev libpq-dev build-essential

```



## Upgrading



Run:



```sh

gem install pgsync

```



To use master, run:



```sh

gem install specific_install

gem specific_install https://github.com/ankane/pgsync.git

```



With Homebrew, run:



```sh

brew upgrade pgsync

```



With Docker, run:



```sh

docker pull ankane/pgsync

```



## Related Projects



Also check out:



- [Dexter](https://github.com/ankane/dexter) - The automatic indexer for Postgres

- [PgHero](https://github.com/ankane/pghero) - A performance dashboard for Postgres

- [pgslice](https://github.com/ankane/pgslice) - Postgres partitioning as easy as pie



## Thanks



Inspired by [heroku-pg-transfer](https://github.com/ddollar/heroku-pg-transfer).



## History



View the [changelog](https://github.com/ankane/pgsync/blob/master/CHANGELOG.md)



## Contributing



Everyone is encouraged to help improve this project. Here are a few ways you can help:



- [Report bugs](https://github.com/ankane/pgsync/issues)

- Fix bugs and [submit pull requests](https://github.com/ankane/pgsync/pulls)

- Write, clarify, or fix documentation

- Suggest or add new features



To get started with development:



```sh

git clone https://github.com/ankane/pgsync.git

cd pgsync

bundle install



createdb pgsync_test1

createdb pgsync_test2

createdb pgsync_test3



bundle exec rake test

```