Add Migration file

db/migrations/00019_create_known_gaps_table.sql

@@ -0,0 +1,10 @@
+-- +goose Up
+CREATE TABLE eth.known_gaps (
+  starting_block_number bigint PRIMARY KEY,
+  ending_block_number bigint,
+  checked_out boolean,
+  processing_key bigint
+);
+
+-- +goose Down
+DROP TABLE eth.known_gaps;

schema.sql

@@ -477,7 +477,7 @@ CREATE TABLE eth.known_gaps (
   starting_block_number bigint PRIMARY KEY,
   ending_block_number bigint,
   checked_out boolean,
-  processing_key INT
+  processing_key bigint
 );