The Indexer data directory is the location where the Indexer can store and/or load data needed for runtime operation and configuration. It is a required argument for Indexer daemon operation. Supply it to the Indexer via the --data-dir flag.
As of mid-2022, approximately 20 GiB for Mainnet.
The data directory is the first place to check for different configuration files, for example:
indexer.yml- Indexer Configuration Fileapi_config.yml- API Parameter Enable/Disable Configuration File
Indexer is effectively a read-only client to the PostgreSQL database. While the configuration must be provided in a data directory, it is only used for configuration.