db: Added Reverse lookup table (#147)

crates/router/src/utils/db_utils.rs

@@ -0,0 +1,10 @@
+#[cfg(feature = "kv_store")]
+/// Generates hscan field pattern. Suppose the field is pa_1234_ref_1211 it will generate
+/// pa_1234_ref_*
+pub fn generate_hscan_pattern_for_refund(sk: &str) -> String {
+    sk.split('_')
+        .take(3)
+        .chain(["*"])
+        .collect::<Vec<&str>>()
+        .join("_")
+}