The indexer application supports two separate services for collective operation:
**Indexer API** - Provides a lightweight API service that supports paginated lookups for bridge events.
**Indexer Service** - A polling based service that constantly reads and persists OP Stack chain data (i.e, block meta, system contract events, synchronized bridge events) from a L1 and L2 chain.
The indexer service is responsible for polling and processing real-time batches of L1 and L2 chain data. The indexer service is currently composed of the following key components:
-**Poller Routines** - Individually polls the L1/L2 chain for new blocks and OP Stack system contract events.
-**Insertion Routines** - Awaits new batches from the poller routines and inserts them into the database upon retrieval.
-**Bridge Routine** - Polls the database directly for new L1 blocks and bridge events. Upon retrieval, the bridge routine will:
* Process and persist new bridge events
* Synchronize L1 proven/finalized withdrawals with their L2 initialization counterparts
### Database
The indexer service currently supports a Postgres database for storing L1/L2 OP Stack chain data. The most up-to-date database schemas can be found in the `./migrations` directory.
**NOTE:** The indexer service implementation currently does not natively support database migration. Because of this a database must be manually updated to ensure forward compatibility with the latest indexer service implementation.
