7.10. Query Interceptors and Guards

GeoMesa provides a chance for custom logic to be applied to a query before executing it. Query interceptors must be specified through user data in the simple feature type, and may be set before calling createSchema, or updated by calling updateSchema. To indicate query interceptors, use the key geomesa.query.interceptors:

sft.getUserData().put("geomesa.query.interceptors", "com.example.MyQueryInterceptor");

The value must be a comma-separated string consisting of the names of one or more classes implementing the trait org.locationtech.geomesa.index.planning.QueryInterceptor:

  * Provides a hook to modify a query before executing it
trait QueryInterceptor extends Closeable {

    * Called exactly once after the interceptor is instantiated
    * @param ds data store
    * @param sft simple feature type
  def init(ds: DataStore, sft: SimpleFeatureType): Unit

    * Modifies the query in place
    * @param query query
  def rewrite(query: Query): Unit

   * Hook to allow interception of a query after extracting the query values
   * @param strategy query strategy
   * @return an exception if the query should be stopped
  def guard(strategy: QueryStrategy): Option[IllegalArgumentException] = None

Interceptors must have a default, no-arg constructor. The interceptor lifecycle consists of:

  1. The instance is instantiated via reflection, using its default constructor

  2. The instance is initialized via the init method, passing in the data store containing the simple feature type

  3. rewrite and guard are called once for each query (these two methods must be thread-safe)

  4. When the data store is disposed, the instance is cleaned up via the close method

Interceptors will be invoked in the order they are declared in the user data. In order to see detailed information on the results of query interceptors, you can enable TRACE-level logging on the class org.locationtech.geomesa.index.planning.QueryRunner$.

7.10.1. Provided Query Guards

GeoMesa provides some basic query guards that will block overly broad queries (which can overwhelm the system). For additional controls, see geomesa.query.timeout and geomesa.scan.block-full-table in Runtime Configuration. Full Table Scan Query Guard

The full table scan query guard will block queries which would cause a full table scan to be performed. The query guard will be loaded in all environments. Alternatively, one can use the geomesa.scan.block-full-table system property to disable full table scans per environment (see Runtime Configuration).

Just like the geomesa.scan.block-full-table property, this guard respects the geomesa.scan.block-full-table.threshold system property. This allows for preview queries which can be helpful to show a system is working.

To enable the guard, add org.locationtech.geomesa.index.planning.guard.FullTableScanQueryGuard to geomesa.query.interceptors as indicated above.


To disable the guard on a per-environment basis, set the system property geomesa.scan.<typeName>.block-full-table to false, where <typeName> is the name of your feature type. Temporal Query Guard

The temporal query guard will block queries which exceed a maximum temporal duration. Any query which attempts to return a larger time period will be stopped. The temporal query guard will not affect queries against indices that do not have a temporal component (for example, feature ID and attribute queries).

To enable the guard, add org.locationtech.geomesa.index.planning.guard.TemporalQueryGuard to geomesa.query.interceptors as indicated above, and set the duration using geomesa.guard.temporal.max.duration:

sft.getUserData().put("geomesa.guard.temporal.max.duration", "28 days");

To disable the guard on a per-environment basis, set the system property geomesa.guard.temporal.<typeName>.disable to true, where <typeName> is the name of your feature type. Graduated Query Guard

The graduated query guard applies different duration limits based on the spatial extent of the query. As a query becomes larger in space, it can be limited to shorter and shorter time ranges. A series of rules limit the duration for queries which are at most a given size in square degrees. This guard also applies the full table scan guard.

To enable the guard, add org.locationtech.geomesa.index.planning.guard.GraduatedQueryGuard to geomesa.query.interceptors as indicated above. Configuration is managed via TypeSafe Config which will look for files named reference.conf and/or application.conf on the classpath. For use in GeoServer, a file name reference.conf can be added to WEB-INF/classes. The configuration is under the key geomesa.guard.graduated.

The configuration must satisfy a few conditions:

  • there must be a limit on unbounded queries,

  • as the size increases, the duration must decrease,

  • and a given size limit may not be repeated.

If no size is provided, it is equivalent to an unbounded size. Durations can be given in a number of days, hours, or minutes. For example:

geomesa {
  guard {
    graduated {
      "sftName" = [
        { size = 1,  duration = "60 days" }
        { size = 10, duration = "3 days"  }
        { duration = "1 day" }

To disable the guard on a per-environment basis, set the system property geomesa.guard.graduated.<typeName>.disable to true, where <typeName> is the name of your feature type.