lncfg: add postgres

docs/postgres.md

@@ -0,0 +1,31 @@
+# Postgres support in LND
+
+With the introduction of the `kvdb` interface, LND can support multiple database
+backends. One of the supported backends is Postgres. This document
+describes how it can be configured.
+
+## Building LND with postgres support
+
+To build LND with postgres support, include the following build tag:
+
+```shell
+⛰  make tags="kvdb_postgres"
+```
+
+## Configuring Postgres for LND
+
+In order for LND to run on Postgres, an empty database should already exist. A
+database can be created via the usual ways (psql, pgadmin, etc). A user with
+access to this database is also required.
+
+Creation of a schema and the tables is handled by LND automatically.
+
+## Configuring LND for Postgres
+
+LND is configured for Postgres through the following configuration options:
+
+* `db.backend=postgres` to select the Postgres backend.
+* `db.postgres.dsn=...` to set the database connection string that includes
+  database, user and password.
+* `db.postgres.timeout=...` to set the connection timeout. If not set, no
+  timeout applies.

docs/release-notes/release-notes-0.14.0.md

@@ -38,6 +38,27 @@ instantaneous. Read the [guide on leader
 election](https://github.com/lightningnetwork/lnd/blob/master/docs/leader_election.md)
 for more information.
 
+### Postgres database support
+
+This release adds [support for Postgres as a database
+backend](https://github.com/lightningnetwork/lnd/pull/5366) to lnd. Postgres
+has several advantages over the default bbolt backend:
+* Better handling of large data sets.
+* On-the-fly database compaction (auto vacuum).
+* Database replication.
+* Inspect data while lnd is running (bbolt opens the database exclusively).
+* Usage of industry-standard tools to manage the stored data, get performance
+  metrics, etc.
+
+Furthermore, the SQL platform opens up possibilities to improve lnd's
+performance in the future. Bbolt's single-writer model is a severe performance
+bottleneck, whereas Postgres offers a variety of locking models. Additionally,
+structured tables reduce the need for custom serialization/deserialization code
+in `lnd`, saving developer time and limiting the potential for bugs.
+
+Instructions for enabling Postgres can be found in
+[docs/postgres.md](../postgres.md).
+
 ## Protocol Extensions
 
 ### Explicit Channel Negotiation