6.6. Runtime Configuration

GeoMesa uses system properties for various runtime configuration options. As a convenience, properties can be specified in an XML file instead of the command line. When run, GeoMesa will load the file geomesa-site.xml from the classpath (if available), and use any properties configured there.

To configure a GeoMesa binary distribution, place geomesa-site.xml in the conf folder. For GeoServer, place the file under geoserver/WEB-INF/classes. For other environments, ensure the file is available at the root level of the classpath.

Each tools distribution contains a template file with the default settings at conf/geomesa-site.xml.template. Do not modify this file directly as it is never read; instead copy the desired configurations into geomesa-site.xml.

By default, system properties set through command line parameters will take precedence over the configuration file. If you wish a configuration item to always take precedence, even over command line parameters, change the <final> tag to true.

Configuration properties with empty values will not be applied, you can change this by marking a property as final.

6.6.1. Common Properties

These properties apply to all GeoMesa implementations. Additional properties for different back-end databases can be found in the chapters for each one.

6.6.1.1. geomesa.audit.provider.impl

This property specifies the fully-qualified class name of an audit provider implementation to use. For more information, see Query Auditing.

6.6.1.2. geomesa.convert.config.urls

This property allows for adding GeoMesa converter configurations to the environment. It can be set to a comma-separated list of arbitrary URLs. For more information on converters, see GeoMesa Convert.

6.6.1.3. geomesa.convert.scripts.path

This property allows for adding files to the classpath. It should be set to a colon-separated list of file paths. This is useful for getting scripts onto the classpath for use by map-reduce ingest jobs.

6.6.1.4. geomesa.distributed.version.check

This property can be used to check for version mismatches in the distributed classpath. When enabled, GeoMesa will throw an exception if it detects a major version discrepancy between the local classpath and the distributed classpath (e.g. HBase region servers or Accumulo tablet servers), as this will generally cause queries to fail. If not enabled, then classpath errors will not be detected proactively, and will likely result in runtime exceptions.

6.6.1.5. geomesa.feature.id-generator

This property controls the default implementation used for generating IDs for simple features, if the USE_PROVIDED_FIDS or PROVIDED_FID hint is not set in the feature. It should be set to the fully-qualified class name for a class implementing org.locationtech.geomesa.utils.uuid.FeatureIdGenerator.

GeoMesa includes an implementing class org.locationtech.geomesa.utils.uuid.Z3FeatureIdGenerator, which creates a unique feature ID partially based on the default time and geometry for the feature. This class is used by default if nothing else is specified, and should work well for most situations.

6.6.1.6. geomesa.filter.hash.threshold

Evaluating a filter of the form name = 'john' OR name = 'jane' OR name = 'doe' can be slow if the number of clauses is high. GeoMesa will optimize such filters by turning them into a hash lookup instead of a sequential comparison. This property controls the threshold for switching to a hash lookup. By default, the threshold is 5.

Note that for datastores with distributed filtering (e.g. HBase and Accumulo), this property needs to be set on the distributed processing nodes.

6.6.1.7. geomesa.force.count

This property controls how GeoMesa calculates the size of a result set (e.g. FeatureSource.getCount). By default, GeoMesa will estimate the size of a result set using statistics. This will provide a rough estimate very quickly. Some applications rely on knowing the exact size of a result set up front, so estimates will cause problems. To force GeoMesa to calculate the exact size of a result set, you may set this property to true. You may also override this behavior on a per-query basis by using the query hint org.locationtech.geomesa.accumulo.index.QueryHints.EXACT_COUNT.

6.6.1.8. geomesa.metadata.expiry

This property controls how often simple feature type metadata is read from the underlying data store. Calls to updateSchema on a data store will not show up in other instances until the metadata cache has expired. The expiry is specified as a duration, e.g. 10 minutes or 1 hour.

6.6.1.9. geomesa.partition.scan.parallel

This property controls how scans against multiple, partitioned tables are executed. By default scans will be executed sequentially. If set to true, they will be executed in parallel. See Configuring Partitioned Indices for details on partitioning.

6.6.1.10. geomesa.query.cost.type

This property controls how GeoMesa performs query planning. By default, GeoMesa will perform cost-based query planning using data statistics to determine the best index for a given query. As a fallback option, this property may be set to index to use heuristic-based query planning. This may also be overridden on a per-query basis using the query hint org.locationtech.geomesa.accumulo.index.QueryHints.COST_EVALUATION_KEY set to either org.locationtech.geomesa.accumulo.index.QueryPlanner.CostEvaluation.Stats or org.locationtech.geomesa.accumulo.index.QueryPlanner.CostEvaluation.Index. See Query Planning for more details on query planning strategies.

6.6.1.11. geomesa.query.decomposition.bits

In addition to geomesa.query.decomposition.multiplier, below, geomesa.query.decomposition.bits sets a lower threshold on the size of the envelopes. It must be between 1 and 63, inclusive. See the Wikipedia article on GeoHashes for the approximate spatial extent of a given number of bits.

6.6.1.12. geomesa.query.decomposition.multiplier

GeoMesa creates scan ranges based on the spatial predicates in a query. For complex spatial predicates, GeoMesa will decompose the geometry into smaller, rectangular envelopes, which avoids scanning over rows which don’t intersect the geometry. This behavior can be controlled through two properties.

geomesa.query.decomposition.multiplier controls the maximum number of envelopes that a geometry will be decomposed into. If set below 2, no decomposition will be performed and instead the geometry envelope will be used. Also see geomesa.query.decomposition.bits, above.

6.6.1.13. geomesa.query.timeout

This property can be used to prevent long-running queries from overloading the system. When set, queries will be closed after the timeout, even if not all results have been returned yet. The timeout is specified as a duration, e.g. 1 minute or 30 seconds.

6.6.1.14. geomesa.scan.block-full-table

This property will prevent full-table scans from executing. A full-table scan is any query that can’t be constrained down using a search index, and thus requires scanning the entire data set. With large data sets, such a scan can last a long time and be resource intensive. The property is specified as a Boolean, i.e. true or false.

For more granularity, it is also possible to specify the full-table scan behavior for individual schemas (SimpleFeatureTypes). Use geomesa.scan.<type-name>.block-full-table, where <type-name> is replaced with the schema name (e.g. “gdelt”). Properties set for an individual schema will take precedence over the globally-defined behavior.

6.6.1.15. geomesa.scan.ranges.target

This property provides a rough upper-limit for the number of row ranges that will be scanned for a single query. It is specified as a number. In general, more ranges will result in fewer false-positive rows being scanned, which will speed up most queries. However, too many ranges can take a long time to generate, and overwhelm clients, causing slowdowns. The optimal value depends on the environment.

6.6.1.16. geomesa.sft.config.urls

This property allows for adding GeoMesa simple feature type configurations to the environment. It can be set to a comma-separated list of arbitrary URLs. For more information on defining types, see Defining Simple Feature Types.

6.6.1.17. geomesa.stats.generate

This property controls whether GeoMesa will generate statistics during ingestion. It is specified as a Boolean, true or false. This property will be used if a data store is not explicitly configured using the geomesa.stats.enable data store parameter.

6.6.1.18. geomesa.strategy.decider

This property allows for overriding strategy selection during query planning. It should specify the full class name for a class implementing org.locationtech.geomesa.index.planning.StrategyDecider. The class must have a no-arg constructor.

By default GeoMesa will use cost-based query planning, which should work well for most situations. See Query Planning for more details on query planning strategies.