sql: release memory when returning connection to the pool

Cargo.toml

@@ -61,7 +61,7 @@ pretty_env_logger = { version = "0.4", optional = true }
 quick-xml = "0.27"
 rand = "0.8"
 regex = "1.7"
-rusqlite = { version = "0.28", features = ["sqlcipher"] }
+rusqlite = { version = "0.28", features = ["sqlcipher", "release_memory"] }
 rust-hsluv = "0.1"
 sanitize-filename = "0.4"
 serde_json = "1.0"

src/sql/pool.rs

@@ -44,6 +44,7 @@ impl Drop for PooledConnection {
         // Put the connection back unless the pool is already dropped.
         if let Some(pool) = self.pool.upgrade() {
             if let Some(conn) = self.conn.take() {
+                conn.release_memory().ok();
                 pool.put(conn);
             }
         }