20.1. Architecture

The GeoMesa FileSystem Datastore (GeoMesa FSDS) takes advantage of the performance characteristics of modern cloud-native and distributed filesystems to scale bulk analytic queries. The FSDS is a good choice for doing bulk egress queries or large analytic jobs using frameworks such as Spark SQL and MapReduce. The FSDS differs from other datastores in that ingest and point query latencies are traded for high-throughput query performance. The FSDS pairs well with low-latency ingest and cache-based datastores systems such as HBase or Kafka to provide an optimal pairing of “hot” and “warm” storage options. This pairing is commonly known as a Lambda Architecture.

The GeoMesa FSDS consists of a few primary components:

  • FileSystem - A separately managed storage system that implements the GeoMesa FileSystem API
  • Partition Scheme - A strategy for laying out data on the filesystem
  • Storage Format - A defined format or encoding to store data in files
  • Query Engine - A query engine or client to fulfill queries and run analytic jobs

20.1.1. FileSystem

GeoMesa FSDS can utilize any filesystem that implements the Hadoop FileSystem API. The most common filesystems used with GeoMesa FSDS are:

  • HDFS - Hadoop Distributed File System
  • S3 - Amazon Simple Storage
  • GCS - Google Cloud Storage
  • WASB - Windows Azure Blob Storage
  • Local - Locally mounted file system (e.g. local disk or NFS)

Choosing a filesystem depends generally on cost and performance requirements. One thing to note is that S3, GCS, and WASB are all “cloud-native” storage meaning that they are built into Amazon, Google, and Microsoft Azure cloud platforms. These cloud-native filesystems are scaled separately from the compute nodes which generally provides a more cost efficient storage solution. Compared to HDFS, their price per GB of storage is lower but their latency is higher. They also have the ability to persist data after you turn off all your compute nodes.

Any of the filesystems mentioned about are good choices for the FSDS. If you have more questions about making a choice contact the GeoMesa team

20.1.2. Partition Schemes

Partition schemes define how data is stored on the filesystem. The scheme is important because it determines how the data is queried. When evaluating a query filter, the partition scheme is leveraged to prune data files that do not match the filter. For more information, see Partition Schemes.

20.1.3. Metadata

The FSDS stores metadata about partitions and data files, to avoid having to repeatedly interrogate the filesystem. By default, metadata information is stored as a change log in the file system. For more advanced use-cases, the FSDS also supports using a relational database. For more information, see FileSystem Metadata.

20.1.4. Storage Formats

  • Apache Parquet - Apache Parquet is the leading interoperable columnar format in the Hadoop ecosystem. It provides efficient compression, storage, and query of structured data.
  • Apache ORC - Apache ORC is a self-describing type-aware columnar file format designed for Hadoop workloads. It is optimized for large streaming reads, but with integrated support for finding required rows quickly.
  • Converter Storage - The converter storage format is a synthetic format which allows you to overlay a GeoMesa converter on top of a filesystem using a defined partition scheme. This allows you to utilize existing data stored in JSON, CSV, TSV, Avro, or other formats. Converters are extensible, allowing users to expose their own custom storage formats if desired. For more details on converters, see GeoMesa Convert. Converter storage is a read-only format.