Create migration_sqlite-postgres.md

docs/system/migration_sqlite-postgres.md

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+# How to migrate from sqlite3 database to postgresql 
+This migration was written while using the unraid template (docker) for TandoorRecipes, version 1.3.0.
+While some commands are unraid specific, it should in general work for any setup.
+
+1. Make a backup of your `/mnt/user/appdata/recipes` dir.
+
+2. Without changing any settings, get a shell into the docker through the WEB-UI or by running `docker exec -it TandoorRecipes /bin/sh`
+```cmd
+cd /opt/recipes
+./venv/bin/python manage.py export -a > /data/dump.json
+```
+
+3. Create a Postgresql database (With a new user & database for recipes)
+
+I used the `postgresql14` template.
+
+```cmd
+psql -U postgres
+postgres=# create database tandoor;
+postgres=# create user tandoor with encrypted password 'yoursupersecretpassworddontusethisone';
+postgres=# grant all privileges on database tandoor to tandoor;
+```
+
+4. Now its time to change some enviourment variables in TandoorRecipes template:
+```env
+DB_ENGINE=django.db.backends.postgresql // Database Engine, previous value: `django.db.backends.sqlite3`
+POSTGRES_HOST=<Your unraid host ip> // PostgreSQL Host
+POSTGRES_PORT=5432 // PostgreSQL Host
+POSTGRES_USER=tandoor //PostgreSQL User
+POSTGRES_PASSWORD=yoursupersecretpassworddyoudidntcopy // PostgreSQL Password
+POSTGRES_DB=tandoor // Database, previous value: `/data/recipes.db`
+```
+
+5. Save it, and start the container once.
+
+It will perform all database migrations once for the postgresql database.
+
+6. Get a shell into the docker through the WEB-UI or by running `docker exec -it TandoorRecipes /bin/sh`
+```cmd
+cd /opt/recipes
+./venv/bin/python manage.py import /data/dump.json
+```
+
+7. Enjoy your new fuzzy search options and SLIGHTLY performance increase!