setup foreign key constraints

nomen/db.py

@@ -13,11 +13,12 @@ schema = """
 PRAGMA user_version = 1;
 
 PRAGMA main.synchronous = NORMAL;
+PRAGMA foreign_keys = ON;
 
 CREATE TABLE keywords (
     guild_id INTEGER NOT NULL,
     keyword TEXT NOT NULL,
-    user_id INTEGER NOT NULL,
+    user_id INTEGER NOT NULL REFERENCES users ON DELETE CASCADE,
     regex INTEGER NOT NULL DEFAULT 0 CHECK(regex IN (0, 1)),
     count INTEGER NOT NULL DEFAULT 0
 );
@@ -38,17 +39,21 @@ CREATE TABLE users (
 WITHOUT ROWID;
 
 CREATE TABLE user_ignores (
-    user_id INTEGER NOT NULL,
+    user_id INTEGER NOT NULL REFERENCES users ON DELETE CASCADE,
     guild_id INTEGER NOT NULL,
     target INTEGER NOT NULL,
     PRIMARY KEY (user_id, guild_id, target)
 );
 
 CREATE TABLE user_blocks (
-    user_id INTEGER NOT NULL,
+    user_id INTEGER NOT NULL REFERENCES users ON DELETE CASCADE,
     target INTEGER NOT NULL,
     PRIMARY KEY (user_id, target)
 );
+
+CREATE INDEX keywords_index ON keywords(user_id);
+CREATE INDEX user_ignores_index ON user_ignores(user_id);
+CREATE INDEX user_blocks_index ON user_blocks(user_id);
 """