etl

type Extract interface {

	// Extract raw records from the source database to be transformed and loaded into the target search index
	Extract(table config.FeatureTable, fields []string, externaFidFields []string,
		where string, limit int, offset int) ([]t.RawRecord, error)

	// Close connection to the source database
	Close()
}

type Load interface {

	// Init the target database by creating an empty search index
	Init(index string, srid int, lang language.Tag) error

	// Get the current version of a collection loaded in the search index
	GetVersion(collectionID string, index string) (string, error)

	// PreLoad hook to execute logic before loading records into the search index.
	// For example, by creating tables or partitions
	PreLoad(collectionID string, index string) error

	// Load records into the search index. Returns the number of records loaded.
	// Assumes the index is already initialized.
	Load(records []t.SearchIndexRecord) (int64, error)

	// PostLoad hook to execute logic after loading records into the search index.
	// For example, by switching partitions or rebuilding indexes.
	PostLoad(collectionID string, index string, collectionVersion string) error

	// Optimize once ETL is completed (optional)
	Optimize() error

	// Close connection to the target database
	Close()
}

type Transform interface {

	// Transform each raw record in one or more search records depending on the given configuration
	Transform(records []t.RawRecord, collection config.GeoSpatialCollection) ([]t.SearchIndexRecord, error)
}