Databases

WeKan stores its data in a MongoDB-compatible database. That can be MongoDB itself, or FerretDB — which speaks the MongoDB wire protocol and stores the data in SQLite, PostgreSQL, MySQL, MariaDB or SAP HANA. The default is FerretDB v1 with its embedded SQLite, so a fresh docker compose up -d needs no database server at all.

Directory	What is in it
FerretDB/1/	FerretDB v1 — the default. SQLite, PostgreSQL, MySQL, MariaDB, SAP HANA
FerretDB/2/	FerretDB 2 — PostgreSQL with the DocumentDB extension
MongoDB/	MongoDB itself: drivers, versions, the OpLog, and old CPUs
Migrations/	WeKan's own schema migrations and how they are verified
ToroDB/	ToroDB — a MongoDB proxy to PostgreSQL. No longer developed

FerretDB

Replacing MongoDB with FerretDB. Both of the v1 backends WeKan ships by default are confirmed working with a real Meteor 3 client — the embedded SQLite and vanilla PostgreSQL (#6509); MySQL, MariaDB and SAP HANA are experimental.

• FerretDB v1 — the five backends, and how to start each
• FerretDB 2 + PostgreSQL install
• https://forums.meteor.com/t/ferretdb-1-18-now-has-oplog-support-trying-replace-mongodb-6-x-with-ferretdb-postgresql-or-ferretdb-sqlite/61092

MongoDB

• Driver-System.md — which Node driver is used for which server version
• Version-Management.md — detecting the server version and switching binaries
• Compatibility-Guide.md — MongoDB 3.0 … 8.0 with Meteor
• Oplog-Configuration.md — why the OpLog matters, and how to enable it
• OpLog-Enablement.md — its status per deployment platform
• avx-qemu.md — MongoDB 5+ on a CPU without AVX
• raspi4-qemu.md — MongoDB 5+ on a Raspberry Pi 4 and older

Migrations

• Migrations/ — the schema-migration system, its review notes and verify-migrations.sh

ToroDB

ToroDB is not developed anymore. ToroDB was about adding a MongoDB proxy to PostgreSQL or MySQL.

• ToroDB/PostgreSQL/ — the compose file and notes kept here