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refactor(peerdb): rewrite postgresql peers sections
This commit is contained in:
Michele Cereda
@@ -10,6 +10,8 @@ Fast, simple, and cost effective Postgres replication.
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1. [Peers](#peers)
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1. [Mirrors](#mirrors)
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1. [Alerts](#alerts)
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1. [PostgreSQL peers](#postgresql-peers)
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1. [AWS RDS PostgresSQL peers](#aws-rds-postgressql-peers)
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1. [Gotchas](#gotchas)
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1. [Further readings](#further-readings)
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1. [Sources](#sources)
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@@ -92,96 +94,6 @@ If Catalog and Temporal are HA, then the whole service is pretty much HA.
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Peers are connection settings to databases that PeerDB can operate upon.
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_Source_ PostgreSQL peers **require** logical replication to be enabled.
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<details style="padding: 0 0 1rem 1rem">
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```sql
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-- Check settings
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sourceDb=> SELECT name,setting FROM pg_settings WHERE name IN ('wal_level','rds.logical_replication');
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name | setting
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-------------------------+---------
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rds.logical_replication | on
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wal_level | logical
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(2 rows)
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```
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```sql
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-- Configure sources
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ALTER SYSTEM SET wal_level = logical;
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ALTER SYSTEM SET max_wal_senders = 10;
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ALTER SYSTEM SET max_replication_slots = 10;
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```
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</details>
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Operations:
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<details style="padding: 0 0 0 1rem">
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<summary>List</summary>
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```sql
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SELECT id, name, type FROM peers;
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```
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```plaintext
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GET /api/v1/peers/list
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```
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</details>
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<details style="padding: 0 0 0 1rem">
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<summary>Create or update</summary>
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```sql
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CREATE PEER IF NOT EXISTS some_postgresql_peer
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FROM POSTGRES
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WITH (
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host='pg.example.org',
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port='5432',
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database='postgres',
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user='postgres',
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password='password'
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);
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```
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| Peer type | `peer.type` attribute | Configuration attribute |
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| ---------- | --------------------- | ----------------------- |
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| ClickHouse | `8` | `clickhouse_config` |
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| Kafka | `9` | `kafka_config` |
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| PostgreSQL | `3` or `'POSTGRES'` | `postgres_config` |
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> The optional `"allow_update": true` attribute in the API seems to do **absolutely nothing** as of the time of writing.
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```plaintext
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POST /api/v1/peers/create
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{
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"allow_update": true,
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"peer": {
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"name": "some_postgresql_peer",
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"type": "POSTGRES",
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"postgres_config": {
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"host": "pg.example.org",
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"port": "5432",
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"database": "postgres",
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"user": "postgres",
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"password": "password"
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}
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}
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}
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```
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</details>
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<details style="padding: 0 0 0 1rem">
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<summary>Delete</summary>
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```sql
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DELETE FROM peers WHERE name == 'some_postgresql_peer';
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```
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</details>
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### Mirrors
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Mirrors can be in the following states:
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@@ -340,6 +252,192 @@ GET /api/v1/alerts/config
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</details>
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## PostgreSQL peers
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> [!caution]
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> Specific implementations of PostgreSQL (e.g., AWS RDS) should be configured in their specific way.<br/>
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> Refer the specific section or upstream documentation.
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Refer [Generic PostgreSQL Source Setup Guide].
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Requirements:
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1. Configure _generic_ _source_ PostgreSQL DBs as follows:
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- WAL level must be set to `logical`.
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- Max WAL senders must be set to a reasonable amount (more than `1` is advised).
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- Max replication slots must be set to a reasonable amount (at least `4` is advised).
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<details style="padding: 0 0 1rem 1rem">
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```sql
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-- Check settings
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postgres=> SELECT name,setting FROM pg_settings WHERE name IN ('wal_level','max_wal_senders','max_replication_slots');
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name | setting
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-------------------------+---------
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max_replication_slots | 20
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max_wal_senders | 35
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wal_level | logical
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(3 rows)
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-- Configure settings
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ALTER SYSTEM SET wal_level = logical;
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ALTER SYSTEM SET max_wal_senders = 10;
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ALTER SYSTEM SET max_replication_slots = 10;
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```
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</details>
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1. Create a DB user with `REPLICATION` permissions.
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<details style="padding: 0 0 1rem 1rem">
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```sql
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CREATE ROLE peerdb WITH LOGIN REPLICATION PASSWORD 'someSecurePassword';
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GRANT USAGE ON SCHEMA public TO peerdb;
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GRANT SELECT ON ALL TABLES IN SCHEMA public TO peerdb;
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ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO peerdb;
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```
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</details>
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1. Create a publication for the mirrors to use.
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<details style="padding: 0 0 1rem 1rem">
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```sql
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CREATE PUBLICATION peerdb FOR ALL TABLES;
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```
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</details>
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Operations:
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<details style="padding: 0 0 0 1rem">
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<summary>List</summary>
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```sql
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SELECT id, name, type FROM peers;
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```
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```plaintext
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GET /api/v1/peers/list
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```
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</details>
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<details style="padding: 0 0 0 1rem">
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<summary>Create or update</summary>
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```sql
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CREATE PEER IF NOT EXISTS some_postgresql_peer
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FROM POSTGRES
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WITH (
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host='pg.example.org',
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port='5432',
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database='postgres',
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user='postgres',
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password='password'
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);
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```
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| Peer type | `peer.type` attribute | Configuration attribute |
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| ---------- | --------------------- | ----------------------- |
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| ClickHouse | `8` | `clickhouse_config` |
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| Kafka | `9` | `kafka_config` |
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| PostgreSQL | `3` or `'POSTGRES'` | `postgres_config` |
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> The optional `"allow_update": true` attribute in the API seems to do **absolutely nothing** as of the time of writing.
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```plaintext
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POST /api/v1/peers/create
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{
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"allow_update": true,
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"peer": {
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"name": "some_postgresql_peer",
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"type": "POSTGRES",
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"postgres_config": {
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"host": "pg.example.org",
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"port": "5432",
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"database": "postgres",
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"user": "postgres",
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"password": "password"
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}
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}
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}
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```
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</details>
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<details style="padding: 0 0 0 1rem">
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<summary>Delete</summary>
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```sql
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DELETE FROM peers WHERE name == 'some_postgresql_peer';
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```
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</details>
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### AWS RDS PostgresSQL peers
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Refer [RDS Postgres Source Setup Guide].
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- Configure _source_ AWS RDS PostgreSQL DBs as follows:
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- RDS logical replication must be enabled.
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- WAL sender timeout must be set to `0`.
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- WAL level must be set to `logical`.
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- Max WAL senders must be set to a reasonable amount (more than `1` is advised).
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- Max replication slots must be set to a reasonable amount (at least `4` is advised).
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<details style="padding: 0 0 1rem 1rem">
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```sql
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-- Check settings
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postgres=> SELECT name,setting
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FROM pg_settings
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WHERE name IN ('rds.logical_replication','wal_sender_timeout','wal_level','max_wal_senders','max_replication_slots');
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name | setting
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-------------------------+---------
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max_replication_slots | 20
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max_wal_senders | 35
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rds.logical_replication | on
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wal_level | logical
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wal_sender_timeout | 0
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(5 rows)
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```
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</details>
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Prefer modifying the settings by creating a parameter group for one's Postgres version and apply that to the RDS
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instance.<br/>
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It will require the instance to be rebooted.
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- Peers need a DB user with `REPLICATION` permissions.<br/>
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AWS RDS does not allow that directly. Assign the `rds_replication` role to that user instead.
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<details style="padding: 0 0 1rem 1rem">
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```sql
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CREATE ROLE peerdb WITH LOGIN PASSWORD 'someSecurePassword';
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GRANT USAGE ON SCHEMA public TO peerdb;
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GRANT SELECT ON ALL TABLES IN SCHEMA public TO peerdb;
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ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO peerdb;
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GRANT rds_replication TO peerdb;
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```
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</details>
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- Create a publication for the mirrors to use.
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<details style="padding: 0 0 1rem 1rem">
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```sql
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CREATE PUBLICATION peerdb FOR ALL TABLES;
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```
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</details>
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||||
## Gotchas
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||||
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||||
- The [documentation] is **sorely lacking**.
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||||
@@ -502,10 +600,12 @@ GET /api/v1/alerts/config
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[blog]: https://blog.peerdb.io/
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[codebase]: https://github.com/PeerDB-io/peerdb
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[documentation]: https://docs.peerdb.io/
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[Generic PostgreSQL Source Setup Guide]: https://docs.peerdb.io/connect/postgres/generic_postgres
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[helm chart]: https://github.com/PeerDB-io/peerdb-enterprise
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[peerdb ui - deeper dive: part 1]: https://blog.peerdb.io/peerdb-ui-deeper-dive-part-1
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[peers.proto#PostgresConfig]: https://github.com/PeerDB-io/peerdb/blob/6a591128908cbd76df8f7e4094ec838fac08dcda/protos/peers.proto#L73
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[public ips for peerdb cloud]: https://docs.peerdb.io/peerdb-cloud/ip-table
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[RDS Postgres Source Setup Guide]: https://docs.peerdb.io/connect/postgres/rds_postgres
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[sql reference]: https://docs.peerdb.io/sql/reference
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[website]: https://www.peerdb.io/
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