Index Basics ============ GeoMesa will create various indices for a given ``SimpleFeatureType`` schema (see :ref:`index_overview`). This allows the execution of a variety of queries in a optimized manner. GeoMesa will make a best effort to determine the attributes used for indexing. The attributes to use can also be specified as part of the ``SimpleFeatureType`` - see :ref:`customizing_index_creation` for details. Spatial Index (Z2/XZ2) ---------------------- If the ``SimpleFeatureType`` has a ``Geometry``-type attribute (``Point``, ``LineString``, ``Polygon``, etc), GeoMesa will create a spatial index on that attribute. If there is more than one ``Geometry``-type attribute, the default one will be used. The default geometry is generally specified with a ``*`` prefix in the ``SimpleFeatureType`` string, and is the one returned by ``SimpleFeatureType.getGeometryDescriptor``. Spatio-temporal Index (Z3/XZ3) ------------------------------ If the ``SimpleFeatureType`` has both a ``Geometry``-type attribute and a ``Date`` attribute, GeoMesa will create a spatio-temporal index on those attributes. The ``Geometry``-type attribute used is the same as for the spatial index, above. The ``Date`` attribute selected will be the first one declared, or can be set explicitly. See :ref:`set_date_attribute` for details on setting the indexed date. ID Index -------- GeoMesa will always create an ID index on ``SimpleFeature.getID()``. .. _attribute_indices: Attribute Index --------------- Some queries are slow to answer using the default indices. For example, with twitter data you might want to return all tweets for a given user. To speed up this type of query, any attribute in your simple feature type may be indexed individually. To index an attribute, add an ``index`` key to the attribute descriptor user data with a value of ``true``. .. note:: Accumulo data stores have an additional option to create reduced 'join' attribute indices, which can save space. See :ref:`accumulo_attribute_indices` for details. .. tabs:: .. code-tab:: java SimpleFeatureType sft = ... sft.getDescriptor("name").getUserData().put("index", "true"); .. code-tab:: scala SchemaBuilder import org.locationtech.geomesa.utils.geotools.SchemaBuilder val sft = SchemaBuilder.builder() .addString("name").withIndex() .addDate("dtg") .addPoint("geom", default = true) .build("mySft") Setting the user data can be done in multiple ways. See :ref:`set_sft_options` for more details. To prioritize certain attributes over others, see :ref:`attribute_cardinality`. .. _index_versioning: Index Versioning ================ In order to ensure cross-compatibility, each index created by GeoMesa has a version number that identifies the layout of data on disk, which is fixed at the time of creation. Updating GeoMesa versions will provide bug fixes and new features, but will not update existing data to new index formats. The exact version of an index used for each schema can be read from the ``SimpleFeatureType`` user data, or by simply examining the name of the index tables created by GeoMesa. The following versions are available: .. tabs:: .. tab:: Z3 ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.1.0 Initial implementation 2 1.2.1 Support for non-point geometries Support for shards 3 1.2.5 Removed support for non-point geometries in favor of xz Removed redundant feature ID in row value to reduce size on disk Support for per-attribute visibility 4 1.3.1 Support for table sharing 5 2.0.0 Uses fixed Z-curve implementation 6 2.3.0 Configurable attributes ============= =============== ================================================================= .. tab:: Z2 ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.2.2 Initial implementation 2 1.2.5 Removed support for non-point geometries in favor of xz Removed redundant feature ID in row value to reduce size on disk Support for per-attribute visibility 3 1.3.1 Optimized deletes 4 2.0.0 Uses fixed Z-curve implementation 5 2.3.0 Configurable attributes ============= =============== ================================================================= .. tab:: XZ3 ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.2.5 Initial implementation 2 2.3.0 Configurable attributes ============= =============== ================================================================= .. tab:: XZ2 ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.2.5 Initial implementation 2 2.3.0 Configurable attributes ============= =============== ================================================================= .. tab:: Attribute ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.0.0 Initial implementation 2 1.1.0 Added secondary date index 3 1.2.5 Removed redundant feature ID in row value to reduce size on disk Support for per-attribute visibility 4 1.3.1 Added secondary Z index 5 1.3.2 Support for shards 6 2.0.0-m.1 Internal row layout change 7 2.0.0 Uses fixed Z-curve implementation 8 2.3.0 Configurable secondary index attributes ============= =============== ================================================================= .. tab:: ID ============= =============== ================================================================= Index Version GeoMesa Version Notes ============= =============== ================================================================= 1 1.0.0 Initial implementation 2 1.2.5 Removed redundant feature ID in row value to reduce size on disk Support for per-attribute visibility 3 2.0.0 Standardized index identifier to 'id' 4 2.3.0 Configurable attributes ============= =============== ================================================================= The version numbers here may not correspond exactly to schemas created with GeoMesa versions prior to 2.3.0, as each back-end implementation initially had its own versioning scheme. However, the implementation for each index was consistent across back-ends in a given GeoMesa release, so if you know the GeoMesa version you can determine the index format from the tables above. Refer to the archived `GeoMesa 2.2.0 documentation`_ to see the back-end-specific index version numbers. .. _GeoMesa 2.2.0 documentation: https://www.geomesa.org/documentation/2.2.0/user/datastores/index_basics.html#index-versioning Note that GeoMesa versions prior to 1.2.2 included a geohash index. That index has been replaced with the Z indices and is no longer supported.