A bit too zealous commenting out some db parts.

That'll be done while merging

docs/ingestion/db.rst

@@ -7,7 +7,7 @@ schema is as follows.
 
 .. literalinclude:: /../extras/db.sql
    :language: sql
-   :lines: 5-7,14-31,50-56
+   :lines: 5-7,94-111,130-136
 
 We do not use any Object-Relational Model (ORM, such as
 SQLAlchemy). Instead, we simply implemented, in SQL, a few functions

extras/db.sql

@@ -8,12 +8,92 @@ CREATE TYPE hash_algo AS ENUM ('md5', 'sha256');
 CREATE EXTENSION pgcrypto;
 
 
+-- ##################################################
+--                        USERS
+-- ##################################################
+CREATE TABLE users (
+        id            SERIAL, PRIMARY KEY(id), UNIQUE(id),
+        elixir_id     TEXT NOT NULL, UNIQUE(elixir_id),
+	password_hash TEXT,
+	pubkey        TEXT,
+	created_at    TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT clock_timestamp(),
+	last_accessed TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT clock_timestamp(),
+	expiration    INTERVAL NOT NULL,
+	CHECK (password_hash IS NOT NULL OR pubkey IS NOT NULL)
+);
+
+CREATE FUNCTION sanitize_id(elixir_id     users.elixir_id%TYPE)
+    RETURNS users.elixir_id%TYPE AS $sanitize_id$
+    DECLARE
+	eid     users.elixir_id%TYPE;
+    BEGIN
+        -- eid := trim(trailing '@elixir-europe.org' from elixir_id);
+	eid := regexp_replace(elixir_id, '@.*', '');
+	RETURN eid;
+    END;
+$sanitize_id$ LANGUAGE plpgsql;
+
+CREATE FUNCTION insert_user(elixir_id     users.elixir_id%TYPE,
+       		    	    password_hash users.password_hash%TYPE,
+       		    	    public_key    users.pubkey%TYPE,
+       		    	    exp_int       users.expiration%TYPE DEFAULT INTERVAL '1' MONTH)
+
+    RETURNS users.id%TYPE AS $insert_user$
+    #variable_conflict use_column
+    DECLARE
+        user_id users.elixir_id%TYPE;
+	eid     users.elixir_id%TYPE;
+    BEGIN
+	eid := sanitize_id(elixir_id);
+	INSERT INTO users (elixir_id,password_hash,pubkey,expiration) VALUES(eid,password_hash,public_key,exp_int)
+	ON CONFLICT (elixir_id) DO UPDATE SET last_accessed = DEFAULT, expiration = exp_int
+	RETURNING users.id INTO user_id;
+	RETURN user_id;
+    END;
+$insert_user$ LANGUAGE plpgsql;
+
+-- Delete other user entries that are too old
+CREATE FUNCTION refresh_user(elixir_id users.elixir_id%TYPE)
+
+    RETURNS void AS $refresh_user$
+    #variable_conflict use_column
+    DECLARE
+	eid     users.elixir_id%TYPE;
+    BEGIN
+	eid := sanitize_id(elixir_id);
+	UPDATE users SET last_accessed = DEFAULT WHERE elixir_id = eid;
+	RETURN;
+    END;
+$refresh_user$ LANGUAGE plpgsql;
+
+CREATE FUNCTION update_users() 
+    RETURNS trigger AS $update_users$ 
+    BEGIN
+        DELETE FROM users WHERE last_accessed < current_timestamp - expiration;
+	RETURN NEW;
+    END;
+$update_users$ LANGUAGE plpgsql;
+
+CREATE TRIGGER delete_expired_users_trigger AFTER UPDATE ON users EXECUTE PROCEDURE update_users();
+
+CREATE FUNCTION flush_user(elixir_id users.elixir_id%TYPE)
+    RETURNS void AS $flush_user$
+    #variable_conflict use_column
+    DECLARE
+	eid     users.elixir_id%TYPE;
+    BEGIN
+	eid := sanitize_id(elixir_id);
+	DELETE FROM users WHERE elixir_id = eid; -- Future: and ega_user is true
+	RETURN;
+    END;
+$flush_user$ LANGUAGE plpgsql;
+
 -- ##################################################
 --                        FILES
 -- ##################################################
 CREATE TABLE files (
         id             SERIAL, PRIMARY KEY(id), UNIQUE (id),
-	elixir_id      TEXT NOT NULL,
+	elixir_id      TEXT REFERENCES users (elixir_id) ON DELETE CASCADE,
 	filename       TEXT NOT NULL,
 	enc_checksum   TEXT,
 	enc_checksum_algo hash_algo,
@@ -55,11 +135,6 @@ CREATE TABLE errors (
 	occured_at    TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT clock_timestamp()
 );
 
--- The reencryption field is used to store how the original unencrypted file was re-encrypted.
--- We gpg-decrypt the encrypted file and pipe the output to the re-encryptor.
--- The key size, the algorithm and the selected master key is recorded in the re-encrypted file (first line)
--- and in the database.
-
 CREATE FUNCTION insert_error(file_id    errors.file_id%TYPE,
                              msg        errors.msg%TYPE,
                              from_user  errors.from_user%TYPE)