Add batch backup

db/migrations/state/validium-001.sql

@@ -0,0 +1,32 @@
+-- +migrate Up
+
+CREATE TABLE IF NOT EXISTS state.batch_data_backup
+(
+    batch_num  BIGINT,
+    data       BYTEA,
+    created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (batch_num, created_at)
+);
+
+-- +migrate StatementBegin
+CREATE OR REPLACE FUNCTION backup_batch() RETURNS trigger AS $$
+    BEGIN
+        INSERT  INTO state.batch_data_backup (batch_num,     data) 
+                VALUES                       (OLD.batch_num, OLD.raw_txs_data)
+                ON CONFLICT (batch_num, created_at) DO UPDATE SET
+                    data = EXCLUDED.data;
+        RETURN OLD;
+    END;
+$$
+LANGUAGE plpgsql;
+-- +migrate StatementEnd
+
+CREATE TRIGGER backup_batch
+   BEFORE DELETE ON state.batch FOR EACH ROW
+   EXECUTE PROCEDURE backup_batch();
+
+-- +migrate Down
+
+DROP TRIGGER IF EXISTS backup_batch ON state.batch;
+DROP FUNCTION IF EXISTS backup_batch();
+DROP TABLE IF EXISTS state.batch_data_backup;

state/pgstatestorage/pgstatestorage.go

@@ -363,6 +363,25 @@ func (p *PostgresStorage) GetBatchL2DataByNumber(ctx context.Context, batchNumbe
 	var batchL2Data []byte
 	err := q.QueryRow(ctx, getBatchL2DataByBatchNumber, batchNumber).Scan(&batchL2Data)
 
+	if errors.Is(err, pgx.ErrNoRows) {
+		return p.GetBatchL2DataByNumberFromBackup(ctx, batchNumber, dbTx)
+	} else if err != nil {
+		return nil, err
+	}
+	return batchL2Data, nil
+}
+
+// GetBatchL2DataByNumberFromBackup returns the batch L2 data of the given batch number from the backup table
+func (p *PostgresStorage) GetBatchL2DataByNumberFromBackup(ctx context.Context, batchNumber uint64, dbTx pgx.Tx) ([]byte, error) {
+	getBatchL2DataByBatchNumber := `
+		SELECT data FROM state.batch_data_backup
+		WHERE batch_num = $1
+		ORDER BY created_at DESC
+		LIMIT 1
+	`
+	q := p.getExecQuerier(dbTx)
+	var batchL2Data []byte
+	err := q.QueryRow(ctx, getBatchL2DataByBatchNumber, batchNumber).Scan(&batchL2Data)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return nil, state.ErrNotFound
 	} else if err != nil {