Switch to a single config option for database connection init

The main pro is less config options, while the main con is less clarity in
what the defaults are for the various database types.

src/db/mod.rs

@@ -140,7 +140,7 @@ macro_rules! generate_connections {
                                 .max_size(CONFIG.database_max_conns())
                                 .connection_timeout(Duration::from_secs(CONFIG.database_timeout()))
                                 .connection_customizer(Box::new(DbConnOptions{
-                                    init_stmts: paste::paste!{ CONFIG. [< $name _conn_init >] () }
+                                    init_stmts: conn_type.get_init_stmts()
                                 }))
                                 .build(manager)
                                 .map_res("Failed to create pool")?;
@@ -215,6 +215,23 @@ impl DbConnType {
             err!("`DATABASE_URL` looks like a SQLite URL, but 'sqlite' feature is not enabled")
         }
     }
+
+    pub fn get_init_stmts(&self) -> String {
+        let init_stmts = CONFIG.database_conn_init();
+        if !init_stmts.is_empty() {
+            init_stmts
+        } else {
+            self.default_init_stmts()
+        }
+    }
+
+    pub fn default_init_stmts(&self) -> String {
+        match self {
+            Self::sqlite => "PRAGMA busy_timeout = 5000; PRAGMA synchronous = NORMAL;".to_string(),
+            Self::mysql => "".to_string(),
+            Self::postgresql => "".to_string(),
+        }
+    }
 }
 
 #[macro_export]