Add indexes for models in postgres

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

heromodels/src/db/postgres.rs

@@ -147,7 +147,17 @@ WHERE table_name = $1
             )
             .map_err(Error::from)?;
 
-            // TODO: Create indexes
+            for indexed_field in M::indexed_fields() {
+                tx.execute(
+                    &format!(
+                        "CREATE INDEX {0}_{1}_idx ON {0} ( (value->'{1}') )",
+                        Self::collection_name::<M>(),
+                        indexed_field,
+                    ),
+                    &[],
+                )
+                .map_err(Error::from)?;
+            }
 
             tx.commit().map_err(Error::from)?;
         }