FME Feature Store (FFS) Writer Parameters

File Parameters

Password

This specification is used to encrypt the output dataset for additional security. This exact passphrase must be used to decrypt this dataset when it is read again.

If this parameter is not used when writing the output dataset, it is not necessary to specify it when reading it in again.

Additional Parameters

Create Spatial Index

If set to Yes, creates and outputs a spatial and feature index for each feature store. The index has the same base name as the FFS file, but will have an .fsi extension. Spatial Indexes are needed if the FFS file is later used as the source for spatial queries or feature types by the FFS reader.

Note  If a spatial index is created, Compression Method and Compression Level are ignored; to allow for efficient random access, a non-compressed .ffs file is output.

Enforce Strict Schema

Indicates whether features should be modified to adhere to the schema. This may include removing all unlisted user attributes before they are saved, or enforcing that attribute types match the type specified on the schema.

  • No – (default) Features will be saved without modification.
  • Yes – Attributes not specified on the schema will be stripped, and attributes specified on the schema will be saved with the specified type.
Note  Strictly adhering to a schema can, in some cases, greatly reduce file size by removing unnecessary attributes. Additionally, enforcing both names and types may dramatically improve read performance of the output file.

Store Scanned Schema

  • Yes – Schemas will be recorded and stored in the output FFS file.
  • No (default) – Schemas will not be passed to the output file.
Note  Storing the scanned schema is in addition to the attributes provided on the writer feature type. When schemas are requested of the output FFS, the writer feature type schema is preferred and returned. However, the scanned schema is accessible through FME Objects, and is useful for improving visualization performance of the FFS file in the FME Data Inspector.

Scan for Types

Specifies whether to try to determine the types of attributes when scanning for schema (when Store Scanned Schema is set to Yes).

  • Yes – FME will attempt to determine the correct type for each attribute (for example, int32, real64, etc.).
  • No – All attributes will be treated as strings.
Note  Choosing to not determine attribute types may dramatically improve writing performance. This option can be set to No if directing data to the FME Data Inspector.

Store Scanned Metadata

  • Yes – Additional metadata will be recorded and stored in the output FFS file.
  • No (default) – Metadata will not be stored in the output file. Metadata includes feature types, geometry types, feature count, and extents.

The scanned metadata is useful for improving visualization performance of the FFS file in the FME Data Inspector.

Compression Parameters

Compression Method

  • LZ4 (fastest) (default) – Reduces the size of the dataset with an algorithm that is fast for both reading and writing. Results in larger file sizes than Zstandard compression.
  • Zstandard – Reduces the size of the dataset with a general-purpose algorithm. Compression Level is used to determine the tradeoff between writing speed and file size.
  • None – Does not reduce the size of the dataset.
Note  Compression is best suited for sequential access; to allow for efficient random access for spatial operations, it is disabled and set to None if Create Spatial Index set to Yes.

Compression Level

Reduces the size of the output dataset. A lower compression level will result in faster operation for both reading and writing, while a higher compression level will result in smaller file sizes.

Note  Compression Level is only used when Compression Method is set to Zstandard.

Advanced

Maximum FFS File Size, in Bytes

Limits the size of each FFS file.

If a file exceeds the specified number of bytes, it will be closed and a new file will be created, with a numeric suffix starting at 1. A single spatial index is created for the group of files.

Note  It may create issues in the workspace if you choose file sizes that are too small for a single feature, or files that are too large for your operating system to support.