18. Merged Data Store View

The GeoMesa Merged Data Store View provides a unified way to query multiple data stores concurrently. For example, you may want to store more recent data in an HBase data store instance, and older data in a FileSystem data store instance to reduce storage costs, but still provide a single layer to query both.


The Merged Data Store View is an alpha-level feature, and may change without notice

In comparison to the Lambda Data Store, the Merged Data Store View does not provide any management for transitioning features between data stores. All writes must be done through the underlying stores directly, and if the same features exist in multiple stores, they may be returned multiple times in a single query response.

In order to use a layer through the Merged Data Store View, the SimpleFeatureType must exist (and match) in all of the underlying stores. If a schema exists in some stores but not all of them, it will not show up in the merged view.

18.1. Installation

The Merged Data Store View is available in the geomesa-index-api JAR, which is bundled by default with all GeoMesa data stores. The underlying stores being merged must be installed separately; see the relevant documentation for each store. Depending on the stores being merged, you may need to resolve classpath conflicts between the store dependencies.

18.2. Usage

The Merged Data Store View can be instantiated through the standard GeoTools DataStoreFinder or the GeoServer New Data Source page. It only requires a single parameter: geomesa.merged.stores.

geomesa.merged.stores should be a TypeSafe Config string the defines the parameters for each merged store. The config should have a top-level key of stores that is a list of objects, where each object is a set of key-value pairs corresponding to the parameters for a single data store.

For example, to merge a GeoMesa Accumulo data store with a PostGis data store, you could use the following config:

stores = [
    "accumulo.zookeepers" = "localhost",
    "accumulo.instance.id" = "test",
    "accumulo.catalog" = "test",
    "accumulo.user" = "test",
    "accumulo.password" = "test"
    "dbtype" = "postgis",
    "host" = "localhost",
    "port" = "5432",
    "database" = "test",
    "user" = "test",
    "passwd" = "test"