# Hosting the Database locally
Hosting a local database has several advantages:
 - Latency is lower, so querying and constructing entry graphs will be faster.
 - If ChemRecon is working with write access to the database, once [procedural relations](../content/schema) have been
    calculated, the result will be cached in the database, optimizing subsequent queries.

Hosting the database requires:
 - An installation of, and working familiarity with, [Docker](https://docs.docker.com/engine/install/).
 - The PostgreSQL client binaries ([Download](https://www.postgresql.org/download/)).
 - Python 3.12.

 1. Clone the Git repository:

    ```
    git clone https://gitlab.com/casbjorn/chemrecon && cd chemrecon
    ```
    
    Use `pip`, `uv`, or a similar tool to set up a Python environment based on the provided `pyproject.toml` file.
 
 2. Use `docker compose` to deploy the database container.
    
    ```
    docker compose -f ./local_db/compose.yaml up
    ```
 
    The `compose.yaml` file contains parameters which can be customized, such as the username and password
    of the default Postgres user account.
    By default, the database port of `5432` will be forwarded to port `54320` on the host machine.
    This behaviour can be changed.

 3. Use the provided initialization script to set up database users and apply the schema.
    This script needs to be provided with access credentials (those defined when deploying the container), as well as
    parameters for the `dev` (write access) user and the public user. By default, it uses those located in
    `.src/chemrecon/database/connection_params`, which can be customized if desired.
    If these files are changed, ChemRecon will use the new parameters when connecting via `connect_local()`
    and `connect_local_dev()`.
    
    ```
    python ./src/chemrecon/scripts/initialize_database.py
    --host=localhost
    --port=54320
    --database=chemrecon_db
    --username=postgres
    --password=testpassword
    --params=./src/chemrecon/database/connection_params/local_docker_pub.dbinfo
    --devparams=./src/chemrecon/database/connection_params/local_docker_dev.dbinfo
    ```
    
 4. Finally, populate the database with data.
    
    Download the dump `.sql` file from TODO.

    Use `pg_restore` to populate the database with this data.

    ```
    pg_restore
    -h=localhost
    -p=54320
    -db_name=chemrecon_db
    -U=postgres
    -W
    --data_only
    "PATH_TO_DOWNLOADED_DUMP_FILE"
    ```
    
    This step may take some time to complete.

After hosting the database, when using ChemRecon, connect with `connect_local()` or `connect_local_dev()` instead of 
`connect_public()` to connect to this database.