Add is-valid feature to allow disabling the "SELECT 1;" is_valid query (#69)

Author: veeshi

Cargo.toml

@@ -39,8 +39,10 @@ features = ["trace"]
 
 
 [features]
+default = ["is-valid"]
 bundled = ["rusqlite/bundled"]
 bundled-sqlcipher = ["rusqlite/bundled-sqlcipher"]
 bundled-sqlcipher-vendored-openssl = [
   "rusqlite/bundled-sqlcipher-vendored-openssl",
 ]
+is-valid = []

src/lib.rs

@@ -161,7 +161,13 @@ impl r2d2::ManageConnection for SqliteConnectionManager {
     }
 
     fn is_valid(&self, conn: &mut Connection) -> Result<(), Error> {
-        conn.execute_batch("SELECT 1;").map_err(Into::into)
+        conn.execute_batch(
+            #[cfg(feature = "is-valid")]
+            "SELECT 1;", // This query can cause performance issues and also may cause errors on non-standard SQLite implementations.
+            #[cfg(not(feature = "is-valid"))]
+            "",
+        )
+        .map_err(Into::into)
     }
 
     fn has_broken(&self, _: &mut Connection) -> bool {